CN112071949A - Ultraviolet detector and preparation method thereof - Google Patents

Ultraviolet detector and preparation method thereof Download PDF

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CN112071949A
CN112071949A CN202010771531.6A CN202010771531A CN112071949A CN 112071949 A CN112071949 A CN 112071949A CN 202010771531 A CN202010771531 A CN 202010771531A CN 112071949 A CN112071949 A CN 112071949A
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mgzno
layer
substrate
seed crystal
ultraviolet detector
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CN112071949B (en
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曹培江
王庆
栾迪
吕有明
朱德亮
柳文军
韩舜
刘新科
许望颖
方明
曾玉祥
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Shenzhen University
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Abstract

The application belongs to the technical field of detectors, and particularly relates to a preparation method of an ultraviolet detector, which comprises the following steps: obtaining a substrate layer, and depositing an MgZnO target on the substrate layer to form an MgZnO seed crystal layer; growing MgZnO nanorods on the MgZnO seed crystal layer to form a MgZnO nanorod array layer; and preparing an electrode on the surface of the MgZnO nanorod array layer, which is away from the MgZnO seed crystal layer, so as to obtain the ultraviolet detector. The preparation method of the ultraviolet detector realizes that different crystal phase tissue seed crystal layers all grow the nanorod arrays with high orientation, improves the surface/volume ratio in the MgZnO nanorod arrays, and ensures that the prepared ultraviolet detector has higher responsivity, lower dark current, higher light-dark current ratio and good ultraviolet detection performance.

Description

Ultraviolet detector and preparation method thereof
Technical Field
The application belongs to the technical field of detectors, and particularly relates to an ultraviolet detector and a preparation method thereof.
Background
The high-sensitivity ultraviolet photoelectric detector has important application in the fields of cell detection, remote control, environmental monitoring, photoelectric integrated circuits and the like. With the continuous progress of semiconductor materials and device preparation processes, a new generation of wide bandgap semiconductor ultraviolet detector overcomes the defects of complex structure, large volume, high energy consumption and the like of the traditional photomultiplier, and becomes a focus of attention in the technical field of ultraviolet detection at present. Meanwhile, the wide bandgap material has the visible blindness, so that the disadvantage that the silicon-based device cannot shield the visible light by itself is effectively overcome. And wide band gap materials are various, including various oxide materials such as ZnO and TiO2、Ga2O3MgZnO, etc. and the materials have stable properties, various preparation methods and low cost and have important application value. In comparison, the MgZnO material has the advantages of low growth temperature (100-750 ℃), continuously adjustable band gap range (3.37-7.8 eV) covering a longer ultraviolet band, stronger radiation resistance, rich raw materials, low cost and the like, so the MgZnO material becomes a research hotspot of the current ultraviolet detector.
Previously, there have been research findings: compared with the traditional film type detector, the detector constructed by the nanorod array has great advantages; the responsivity of the MgZnO nanorod array type ultraviolet detector is improved to a certain extent compared with that of a MgZnO film type ultraviolet detector. However, at present, it is still difficult to successfully and controllably dope ZnO with Mg, and it is difficult to increase the doping content of Mg and maintain the vertical structure of the nanorod array, and the current research is still in the exploration stage, and the research work of the system is still less. In addition, the dark current, light-dark current ratio, responsivity and other properties of the existing ultraviolet detector are still to be further improved.
Disclosure of Invention
The application aims to provide an ultraviolet detector and a preparation method thereof, and aims to solve the problems that the existing MgZnO nanorod array type ultraviolet detector is difficult to prepare and the dark current, the light-dark current ratio, the responsivity and other properties of the detector need to be further improved to a certain extent.
In order to achieve the purpose of the application, the technical scheme adopted by the application is as follows:
in a first aspect, the present application provides a method for manufacturing an ultraviolet detector, including the following steps:
obtaining a substrate layer, and depositing an MgZnO target on the substrate layer to form an MgZnO seed crystal layer;
growing MgZnO nanorods on the MgZnO seed crystal layer to form a MgZnO nanorod array layer;
and preparing an electrode on the surface of the MgZnO nanorod array layer, which is away from the MgZnO seed crystal layer, so as to obtain the ultraviolet detector.
In a second aspect, the present application provides an ultraviolet detector, including a substrate, a MgZnO seed crystal layer, a MgZnO nanorod array layer and an electrode, which are sequentially stacked.
According to the preparation method of the ultraviolet detector provided by the first aspect of the application, the MgZnO seed crystal layer grows on the substrate in advance, and the MgZnO nanorod array with high density, high orientation and large specific surface area grows and forms by taking MgZnO in the seed crystal layer as a crystal nucleus through chemical vapor deposition. According to the preparation method of the ultraviolet detector, high-orientation nanorod arrays can be grown on different crystalline phase tissue seed crystal layers, the surface/volume ratio of the MgZnO nanorod arrays is improved, and the prepared ultraviolet detector has high responsivity, low dark current, high light dark current ratio and good ultraviolet detection performance.
In the ultraviolet detector provided by the second aspect of the present application, the included MgZnO seed layer, the MgZnO nanorod array layer and the electrode are stacked, when ultraviolet light irradiates the detector, photons are absorbed by semiconductor materials such as the MgZnO seed layer and the MgZnO nanorod array, so that electrons in a valence band jump to a conduction band to generate a hole electron pair, and then under the action of an external electric field or a built-in electric field, carriers migrate to form photocurrent, which is collected by the electrodes at two ends, so that optical signals are converted into electrical signals, and ultraviolet detection is realized.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic flow chart of a method for manufacturing an ultraviolet detector provided by an embodiment of the present application;
FIG. 2 is a schematic diagram of an array of raw materials in a CVD tube furnace in a method for manufacturing an ultraviolet detector according to an embodiment of the present application;
FIG. 3 is a schematic structural diagram of an ultraviolet detector provided in an embodiment of the present application;
FIG. 4 is an XRD pattern of MgZnO nanorod arrays grown in examples 1-3 of the present application;
FIG. 5 is a SEM image of MgZnO nanorods arrays grown in examples 1-3 of the present application;
FIG. 6 is a sectional EDS diagram of MgZnO nanorod arrays grown in examples 1-3 of the present application;
FIG. 7 shows the responsivity and the ratio of dark current to light of the UV detector prepared in examples 1-3 of the present application;
FIG. 8 is the responsivity of the UV detector prepared in example 2 of the present application and the UV detector prepared in comparative example 1;
FIG. 9 is an XRD pattern of MgZnO seed layer films grown in examples 1 to 4 of the present application.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application more clearly apparent, the present application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In the present invention, the term "and/or" describes the association relationship of the associated objects, and means that there may be three relationships, for example, a and/or B, which may mean: a is present alone, A and B are present simultaneously, and B is present alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
In the present invention, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (one) of a, b, or c," or "at least one (one) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, and c may be single or plural, respectively.
It should be understood that, in various embodiments of the present invention, the sequence numbers of the above-mentioned processes do not mean the execution sequence, some or all of the steps may be executed in parallel or executed sequentially, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The weight of the related components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, the content of the related components is scaled up or down within the scope disclosed in the description of the embodiments of the present invention as long as it is in accordance with the description of the embodiments of the present invention. Specifically, the mass in the description of the embodiments of the present invention may be a mass unit known in the chemical industry field such as μ g, mg, g, kg, etc.
The terms "first" and "second" are used for descriptive purposes only and are used for distinguishing purposes such as substances from one another, and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. For example, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX, without departing from the scope of embodiments of the invention. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
In a first aspect, an embodiment of the present application provides a method for manufacturing an ultraviolet detector, including the following steps:
s10, obtaining a substrate layer, and depositing an MgZnO target on the substrate layer to form an MgZnO seed crystal layer;
s20, growing MgZnO nanorods on the MgZnO seed crystal layer to form a MgZnO nanorod array layer;
and S30, preparing an electrode on the surface of the MgZnO nanorod array layer, which is away from the MgZnO seed crystal layer, and obtaining the ultraviolet detector.
According to the preparation method of the ultraviolet detector provided by the first aspect of the application, firstly, a MgZnO seed crystal layer is prepared on a substrate layer, then, the MgZnO seed crystal layer is used as an induction layer, and a MgZnO nanorod array doped with Mg is grown on the seed crystal layer in a chemical vapor deposition mode and the like to form a MgZnO nanorod array layer; and finally, preparing an electrode on the MgZnO nanorod array layer to construct the MgZnO nanorod array type ultraviolet detector. According to the preparation method of the ultraviolet detector, the MgZnO seed crystal layer grows on the substrate in advance, and the MgZnO nanorod array with high density, high orientation and large specific surface area grows through vapor deposition by taking the MgZnO in the seed crystal layer as a crystal nucleus. In addition, MgZnO seed crystal layers with different phase structures can influence parameters such as the surface density of MgZnO nanorods grown on the surface at the later stage. The preparation method of the ultraviolet detector provided by the embodiment of the application realizes that different crystal phase tissue seed crystal layers all grow the nanorod array with high orientation, improves the surface/volume ratio in the MgZnO nanorod array, and enables the prepared ultraviolet detector to have higher responsivity, lower dark current, higher light dark current ratio and good ultraviolet detection performance.
In some embodiments, the method for manufacturing the UV detector of the present application is schematically illustrated in FIG. 1, wherein PLD represents pulsed laser deposition, CVD represents chemical vapor deposition, and nanoros arrays represents grown MgZnO nanorod arrays. The parameters of the substrate layer material selection, the thickness of the functional layers, etc. in fig. 1 are merely representative of the situation in one embodiment and are not exclusive.
Specifically, in step S10, the step of depositing the MgZnO target on the substrate layer includes: the molar ratio of Mg element to Zn element is 1: (0.43-2.33) depositing the target material on the substrate layer for 120-150 min under the conditions that the substrate temperature is 200-500 ℃, the oxygen pressure is 2-6 Pa, the oxygen flow is 8-12 sccm, the substrate-target distance is 40-80 mm, the laser energy is 200-400 mJ, and the laser frequency is 3-6 Hz, so as to form the MgZnO seed crystal layer.
In the embodiment of the application, on one hand, the molar ratio of the Mg element to the Zn element is 1: (0.43-2.33) MgZnO target material, such as: mg (magnesium)0.3Zn0.7The O target material represents that the molar ratio of Mg element to Zn element in the target material is 0.3:0.7, the sum of the molar ratio of the Mg element to the Zn element is 1, the ratio of the total molar amount of Mg and Zn metal elements in the target material to the molar amount of oxygen element is 1:1, the MgZnO seed crystal layer with different crystal phase tissues and the MgZnO seed crystal layer with different crystal phase tissues can be formed by the target material with the element ratio through deposition methods such as pulse laser and the like, wherein the MgZnO seed crystal layer has the same single cubic phase, the single hexagonal phase and the mixture of the cubic phase and theThe MgZnO seed crystal layer provides conditions for the subsequent growth of MgZnO nanorod arrays with different crystalline phase structures. If the content of the magnesium element in the MgZnO target is too high, the MgZnO seed crystal layer with hexagonal phase, cubic phase and mixed phase can not be formed by deposition. On the other hand, in the deposition temperature range of 200-500 ℃, the MgZnO crystal phase structure formed by deposition is changed from cubic phase to hexagonal phase along with the rise of temperature, and when the temperature is about 200 ℃, a single cubic phase crystal MgZnO crystal seed layer is formed; when the temperature is increased to about 300 ℃, part of crystalline phase tissues are changed from cubic phase to hexagonal phase, and the formed MgZnO crystalline phase tissues are mixed phases of cubic phase and hexagonal phase; when the temperature is raised to about 400 ℃, the crystal phase conversion is complete, and a single hexagonal MgZnO seed crystal layer is formed. On the other hand, the deposition conditions such as oxygen pressure, target distance, laser energy and the like can influence the migration energy of various clusters deposited on the surface of the substrate by MgZnO, thereby influencing the microstructure morphology of the MgZnO. The deposition conditions such as oxygen flow, deposition time, laser frequency and the like can influence the adsorption time of various MgZnO clusters adsorbed on the surface of the substrate, and influence the number of various deposited MgZnO clusters received by the surface of the substrate in unit time and unit area, thereby influencing the growth rate and the thickness of the MgZnO seed crystal layer. If the substrate temperature is lower than 200 ℃, the defect density is higher and the surface roughness is higher when the MgZnO seed crystal layer grows. If the temperature of the substrate is higher than 500 ℃, thermal mismatch occurs due to different thermal expansion coefficients between the substrate and the MgZnO seed crystal layer, and the generated thermal stress enables the surface of the MgZnO seed crystal layer to present an obvious crystal boundary, so that the surface flatness of the MgZnO seed crystal layer is reduced, and the subsequent growth of MgZnO nanorods is not facilitated.
In some embodiments, in the MgZnO seed layer, the MgZnO crystals are cubic and/or hexagonal in phase, i.e., include: single cubic phase, single hexagonal phase, cubic and hexagonal mixed phases. In some embodiments, the MgZnO seed layer is a single cubic phase MgZnO crystal. In other embodiments, the MgZnO seed layer is a single hexagonal phase MgZnO crystal. In other embodiments, the MgZnO seed layer is a cubic and hexagonal phase mixed phase MgZnO crystal.
In some embodiments, the MgZnO seed layer has a thickness of 200 to 500 nanometers. In the embodiment of the application, the thickness of the MgZnO seed crystal layer has a crucial influence on the subsequent growth of the MgZnO nanorod array, and the MgZnO seed crystal layer with the thickness of 200-500 nanometers is most beneficial to the subsequent growth to obtain the large-area, continuous, monodisperse and high-orientation MgZnO nanorod array. When the thickness of the MgZnO seed crystal layer is less than 200 nanometers, a large-area, continuous and monodisperse MgZnO nanorod array is difficult to grow on the surface of the MgZnO seed crystal layer; and when the thickness of the MgZnO seed layer exceeds 500nm, the vertical orientation performance of the MgZnO nano-rod is weakened.
Specifically, in step S20, the step of growing MgZnO nanorods on the MgZnO seed layer includes: the method comprises the steps of obtaining zinc oxide, magnesium powder and carbon powder, placing a mixture of the zinc oxide and the carbon powder, the magnesium powder and a substrate with a MgZnO seed crystal layer in a vapor deposition system, heating to 800-1000 ℃ under the conditions that the pressure is 2-3 torr and the flow of protective gas is 25-35 sccm, providing oxygen with the flow of 1-3 sccm, preserving heat for 20-40 min, cooling, and forming the MgZnO nanorod array layer on the surface of the MgZnO seed crystal layer, which is far away from the substrate.
On one hand, the embodiment of the application takes zinc oxide, magnesium powder and carbon powder as raw materials, and a MgZnO nanorod array doped with magnesium is grown on a MgZnO seed crystal layer by a chemical vapor deposition method. Because the volatilization point of the simple substance zinc is low and the stability is poor, the simple substance zinc can be volatilized too fast at high temperature and is deposited on the substrate combined with oxygen, so that a large-particle ZnO crystal nucleus is easily formed, the doping of magnesium atoms is not facilitated, and MgZnO nanometer crystal nucleus particles are difficult to deposit and form, thereby being not beneficial to the MgZnO nanometer crystal nucleus particles to grow a MgZnO nanometer rod array with good verticality under the induction of a crystal seed layer. Therefore, in the embodiment of the application, zinc oxide is used as a zinc source, and under the high-temperature vapor deposition condition, carbon powder has a reducing effect on the zinc oxide, so that free zinc atoms and carbon dioxide are generated in a vapor deposition system, and the zinc source is provided for the growth of the MgZnO nanorod. Free zinc atoms and free magnesium atoms generated by heating magnesium powder are deposited on a seed crystal layer of a substrate to generate MgZnO nano crystal nucleus particles under the action of oxygen, and MgZnO nano rods are formed by the induced growth of the MgZnO seed crystal layer. In addition, CO is formed2Gas (es)And the gas is discharged along with the carrier gas, so that other impurity elements are not introduced, and the high-purity MgZnO nanorod is favorably generated. On the other hand, the conditions that the pressure is 2-3 torr and the flow of the protective gas is 25-35 sccm are favorable for avoiding early magnesium from generating MgO with a high evaporation point, so that the magnesium is better doped into ZnO to generate the MgZnO nanorod array. The temperature condition of 800-1000 ℃ is favorable for growing and forming the MgZnO nanorod array with smaller diameter, high density and good monodispersity, thereby improving the effective comparison area of the MgZnO nanorod array, increasing the absorption and the induction of the detector to light and improving the detection sensitivity. In addition, if the heat preservation time is too short, the length of the grown MgZnO nanorod is too short, the specific surface area of the effective nanorod is small, and the generated photocurrent is small, so that the performance during the ultraviolet detection period is reduced. If the heat preservation time is too long, the length of the grown MgZnO nanorod is too long, so that the verticality of the nanorod is poor, the ultraviolet light absorption is not facilitated, and the responsivity of the final device is reduced.
In some embodiments, zinc oxide, magnesium powder and carbon powder are obtained for vapor deposition, and chemical vapor deposition is performed in a tube furnace by adopting a mode of sleeving an outer tube and an inner tube, and the method specifically comprises the following steps: (1) as shown in the attached figure 2, a mixture of zinc oxide and carbon powder, magnesium powder and a substrate (substrate) with a MgZnO seed crystal layer formed are placed in an inner small quartz tube, one end of the small quartz tube is closed, the other end of the small quartz tube is opened, the opening end of the small quartz tube is positioned at the downstream end of an air flow, then, the short tube is slowly pushed into the quartz tube, the initial reactant is positioned at the heating center of a tube furnace, and a flange is installed; (2) and sequentially starting the tube furnace, the gas flow meter and the vacuum pump to vacuumize the quartz tube, and closing the vacuum pump when the pressure is lower than 2-3 torr. Subsequently opening respective O2And N2Cleaning with at least one protective gas of Ar, recovering normal pressure, vacuumizing, and removing O2The gas is cleaned once, and the protective gas is cleaned repeatedly for three times. Then adjusting the flow (25-35 sccm) of the protector, opening a valve to exhaust when the normal pressure in the pipe is recovered, and treating tail gas in water; (3) setting the experiment heat preservation temperature to be 800-1000 ℃, the heat preservation time to be 30min and the temperature rise and fall rate to be 5-15 ℃/min and starting to heat; (4) when the temperature reaches the temperature required by the reactionWhen the temperature is close to the preset value, taking the exhaust pipe out of the water, closing an exhaust valve, and then opening a vacuum pump to vacuumize to 2-3 torr; (5) adjusting O when the temperature reaches a predetermined temperature2The flow is 1-3 sccm, heat preservation is started, the oxygen valve is closed after the heat preservation time is over, and the temperature of the tube furnace is reduced; (6) when the temperature of the tube furnace is reduced to below 500 ℃, closing the air suction valve and the mechanical pump, opening the exhaust port valve after the pressure in the tube is recovered to the normal pressure, and inserting the exhaust pipe into water; when cooled below 200 ℃, the tube furnace, flow meter and gas cylinder were closed and the experiment was finished. In step (1) of the embodiment of the present application, the mixture of zinc oxide and carbon powder, magnesium powder, and the substrate on which the MgZnO seed crystal layer is formed are disposed at positions such that elemental Mg element is evaporated at a relatively low temperature, and then Mg vapor atoms move toward the surface of the substrate, react with oxygen near the end of the right-side opening to form an oxide, and are doped into zinc oxide. If oxygen firstly reacts with the simple substance Mg element to form magnesium oxide, magnesium oxide steam molecules cannot be formed due to the extremely high volatilization point temperature of the magnesium oxide, so that zinc oxide cannot be effectively doped, and MgZnO nanorods cannot be grown.
In some embodiments, the mass ratio of zinc oxide to carbon powder to magnesium powder is 1: 1: (0.5-0.8), the raw material components in the mass ratio are favorable for the growth of the MgZnO nano-rod doped with magnesium. If the content of the magnesium powder is too low, Mg atoms are not favorably doped into the ZnO nanorods, and the Mg doping in the MgZnO nanorods is too little to play a role in regulating and controlling the band gap; due to the characteristics of the MgZnO material, the maximum magnesium content doped by a chemical method is about 4 percent, and the effective doping of magnesium atoms is difficult to improve due to the over-high magnesium powder content. According to the raw material components in the proportion, the MgZnO nanorod with the magnesium doping amount of 2.64% -3.73% can be prepared, and the performance of the detector is favorably improved.
In some embodiments, in the MgZnO nanorod array layer, the MgZnO nanorods have a length of 40-55 microns; the diameter of the MgZnO nano rod is 200-300 nanometers. The MgZnO nanorods in the MgZnO nanorod array layer prepared by the embodiment of the invention have higher length-diameter ratio and large specific surface area, so that the effective comparative area of the MgZnO nanorod array layer is increased, the absorption and induction of a detector to ultraviolet light are favorably improved, and the detection sensitivity and responsivity of a device to the ultraviolet light are further improved. If the length of the nano rod is too short and the diameter of the nano rod is too large, the area for effectively receiving ultraviolet light is reduced, and the performance of the ultraviolet detector is reduced. If the length of the nano rod is too long and the diameter of the nano rod is too small, the verticality of the nano rod can be reduced, the top end of the nano rod is bent, and the shielding material absorbs ultraviolet light, so that the performance of the detector is reduced.
In some embodiments, the MgZnO nanorod array layer has an areal density of 4.9 × 107Root/cm2～7.3×107Root/cm2. The MgZnO nanorods in the MgZnO nanorod array layer grown in the embodiment of the application have moderate density, so that the surface/volume ratio of the MgZnO nanorods array is large, and the sensitivity and the responsiveness of a detection device to ultraviolet light are favorably improved. If the surface density of the MgZnO nanorod array is too low, the unit effective area of the MgZnO nanorod array layer for receiving light is reduced; if the surface density of the MgZnO nanorod array is too high, light is difficult to enter the array layer, and the area of the MgZnO nanorod array, which effectively receives ultraviolet light, is reduced, so that the responsivity of the detector is reduced.
Specifically, in step S30, the step of preparing the electrode includes: two opposite metal electrodes are deposited on the surface of the MgZnO nanorod array layer, the length multiplied by the width of the metal electrodes is (2-3) mm multiplied by (2-3) mm, and the distance is 0.5-2.5 mm. The electrode size that this application embodiment prepared is little, and the interval is big, is favorable to improving the detector area of receiving ultraviolet irradiation to be favorable to the promotion of detector performance. In some specific embodiments, a silver electrode is prepared at the fixed end of the MgZnO nanorod array layer by coating with conductive silver adhesive, and a Pt wire is used as a lead to connect the electrode.
In some embodiments, the substrate layer may be a silicon-based SiO2One of a/Si substrate, a sapphire substrate and a quartz substrate. In some embodiments, the substrate layer is made of SiO2When the substrate is a/Si composite substrate, SiO in the substrate layer2The thickness of the layer is 300-500 nm, the substrate layer with the thickness has good insulating property, has better supporting effect on the functional layer grown subsequently, and avoids the problem of low costThe substrate is too thick, the overall weight of the detector is increased, and flexible application is not facilitated.
The second aspect of the embodiment of the application provides an ultraviolet detector, which comprises a substrate layer, a MgZnO seed crystal layer, a MgZnO nanorod array layer and an electrode which are sequentially stacked.
In the ultraviolet detector provided by the second aspect of the present application, the included MgZnO seed layer, the MgZnO nanorod array layer and the electrode are stacked, when ultraviolet light irradiates the detector, photons are absorbed by semiconductor materials such as the MgZnO seed layer and the MgZnO nanorod array, so that electrons in a valence band jump to a conduction band to generate a hole electron pair, and then under the action of an external electric field or a built-in electric field, carriers migrate to form photocurrent, which is collected by the electrodes at two ends, so that optical signals are converted into electrical signals, and ultraviolet detection is realized. According to the detector provided by the embodiment of the application, on one hand, the MgZnO seed crystal layer can obviously reduce the dark current of the detector, so that the light dark current ratio is improved, the performance of a device is finally improved, meanwhile, the MgZnO seed crystal layer also has the ultraviolet detection performance, and the effective detection wavelength range of the device can be widened. On the other hand, the MgZnO nanorod array layer greatly improves the effective specific surface area of the detector, improves the receiving area of ultraviolet photons, and improves the formation quantity and recombination efficiency of electron hole pairs in the detector, thereby improving the performance of the ultraviolet detector. On the other hand, the MgZnO seed crystal layer can provide an induction matrix for the formation of the MgZnO nanorod array layer, and the cooperation of the MgZnO seed crystal layer and the MgZnO nanorod array layer is beneficial to improving the detection sensitivity of the ultraviolet detector to light, reducing dark current, improving the light-dark current ratio and enabling the ultraviolet detection performance to be better.
The ultraviolet detector provided by the embodiment of the application can be prepared by the method of any one of the embodiments. In some embodiments, the ultraviolet detector is schematically shown in fig. 3.
In some embodiments, in the MgZnO nanorod array layer, the MgZnO nanorod array is perpendicular to the MgZnO seed crystal layer, and the orientation of the nanorod array is good.
In some embodiments, in the MgZnO nanorod array layer, the MgZnO nanorods have a length of 40-55 microns; the diameter of the MgZnO nano rod is 200-300 nanometers.
In some embodiments, the MgZnO nanorod array layer has an areal density of 4.9 × 107Root/cm2～7.3×107Root/cm2。
In some embodiments, the MgZnO seed layer has a thickness of 200 nanometers to 500 nanometers.
In some embodiments, in the MgZnO seed layer, the MgZnO crystals are cubic and/or hexagonal in phase, i.e., include: single cubic phase, single hexagonal phase, cubic and hexagonal mixed phases.
In some embodiments, the substrate layer is selected from: SiO 22One of a/Si substrate, a sapphire substrate and a quartz substrate. In some embodiments, the substrate layer is made of SiO2In the case of a/Si substrate, SiO2The thickness of the layer is 300-500 nm.
The technical effects of the above embodiments of the present application are discussed in the foregoing, and are not described herein again.
In order to make the above implementation details and operations of the present application clearly understood by those skilled in the art, and to make the advanced performance of the ultraviolet detector and the manufacturing method thereof obvious in the embodiments of the present application, the above technical solution is illustrated by a plurality of embodiments.
Example 1
An ultraviolet detector comprises the following preparation methods:
1. coating a piece of SiO with a thickness of 300nm2SiO of (2)2a/Si substrate.
2. Using Pulsed Laser Deposition (PLD) with Mg0.3Zn0.7O target material in SiO2On a Si substrate, growing a single cubic phase MgZnO film with the thickness of about 300nm on the condition that the oxygen pressure is 4.0Pa, the deposition time is 120-150 min, the oxygen flow is 10sccm, the base target spacing is 60mm, the laser energy is 300mJ, the laser frequency is 5Hz, and the substrate temperature is 200 ℃ to form the single cubic phase MgZnO seed crystal layer.
3. Obtaining zinc oxide, magnesium powder and carbon powder to carry out vapor deposition, and carrying out chemical vapor deposition by adopting a mode of an outer sleeve inner tube in a tube furnace, wherein the method specifically comprises the following steps:
firstly, as shown in figure 2, a mixture of 0.5g of zinc oxide and 0.5g of carbon powder, 0.2914g of magnesium powder and a substrate formed with a MgZnO seed crystal layer are placed in a small quartz tube inside, one section of the small quartz tube is closed, the other end of the small quartz tube is open, the open end of the small quartz tube is positioned at the downstream end of an air flow, then a short tube is slowly pushed into the quartz tube, the initial reactant is positioned at the heating center of a tube furnace, and a flange is installed;
and secondly, starting the tube furnace, the gas flow meter and the vacuum pump in sequence to vacuumize the quartz tube, and closing the vacuum pump when the pressure is lower than 2 torr. Subsequently opening respective O2Cleaning with Ar gas, recovering normal pressure, continuously vacuumizing and exhausting, and removing O2The gas is cleaned once, and the Ar gas is cleaned repeatedly for three times. Then adjusting the flow (30sccm) of the protector, opening a valve to exhaust when the normal pressure in the pipe is recovered, and treating tail gas in water;
setting the experiment heat preservation temperature of 900 ℃, the heat preservation time and the temperature rise and fall rate of 10 ℃/min and starting to heat;
when the temperature reaches the temperature near the temperature required by the reaction, taking the exhaust pipe out of the water, closing an exhaust valve, and then opening a vacuum pump to vacuumize to 2 torr;
adjusting O when the temperature reaches the preset temperature2The flow is 1.5sccm, the heat preservation is started, the oxygen valve is closed after the heat preservation time is over, and the temperature of the tube furnace is reduced;
closing the air exhaust valve and the mechanical pump when the temperature of the tube furnace is reduced to be below 500 ℃, opening the air exhaust valve after the pressure in the tube is restored to normal pressure, and inserting the air exhaust pipe into water; and when the temperature is cooled to be below 200 ℃, closing the tube furnace, the flow meter and the gas cylinder, and ending the experiment to obtain the MgZnO nanorod array layer.
4. Covering the electrode mask on the top of the grown MgZnO nanorod array layer, and fixing the periphery with an adhesive tape to prevent the conductive silver adhesive from escaping to the side of the sample to influence the test. Then use tweezers to press the mask gently, reduce its gap with the array top. Subsequently, the conductive silver paste was uniformly coated with a brush, the mask was removed and a platinum wire was connected to the coated conductive silver paste. And finally, placing the sample in an oven at 80 ℃ for standing for 30min to solidify the conductive silver adhesive, and finishing the preparation process to obtain the single cubic-phase MgZnO nanorod array type ultraviolet detector.
Example 2
An ultraviolet detector comprises the following preparation methods:
1. coating a piece of SiO with a thickness of 300nm2SiO of (2)2a/Si substrate.
2. Using Pulsed Laser Deposition (PLD) with Mg0.3Zn0.7O target material in SiO2On a Si substrate, growing a cubic phase and hexagonal phase mixed MgZnO film on the conditions that the oxygen pressure is 4.0Pa, the deposition time is 120-150 min, the oxygen flow is 10sccm, the base target spacing is 60mm, the laser energy is 300mJ, the laser frequency is 5Hz, and the substrate temperature is 300 ℃, wherein the thickness of the film is about 300nm, and a cubic phase and hexagonal phase mixed MgZnO seed crystal layer is formed.
3. Obtaining zinc oxide, magnesium powder and carbon powder to carry out vapor deposition, and carrying out chemical vapor deposition by adopting a mode of an outer sleeve inner tube in a tube furnace, wherein the method specifically comprises the following steps:
firstly, as shown in figure 2, a mixture of 0.5g of zinc oxide and 0.5g of carbon powder, 0.2914g of magnesium powder and a substrate formed with a MgZnO seed crystal layer are placed in a small quartz tube inside, one section of the small quartz tube is closed, the other end of the small quartz tube is open, the open end of the small quartz tube is positioned at the downstream end of an air flow, then a short tube is slowly pushed into the quartz tube, the initial reactant is positioned at the heating center of a tube furnace, and a flange is installed;
and secondly, starting the tube furnace, the gas flow meter and the vacuum pump in sequence to vacuumize the quartz tube, and closing the vacuum pump when the pressure is lower than 2 torr. Subsequently opening respective O2Cleaning with Ar gas, recovering normal pressure, continuously vacuumizing and exhausting, and removing O2The gas is cleaned once, and the Ar gas is cleaned repeatedly for three times. Then adjusting the flow (30sccm) of the protector, opening a valve to exhaust when the normal pressure in the pipe is recovered, and treating tail gas in water;
setting the experiment heat preservation temperature of 900 ℃, the heat preservation time and the temperature rise and fall rate of 10 ℃/min and starting to heat;
when the temperature reaches the temperature near the temperature required by the reaction, taking the exhaust pipe out of the water, closing an exhaust valve, and then opening a vacuum pump to vacuumize to 2 torr;
adjusting O when the temperature reaches the preset temperature2The flow is 1.5sccm, the heat preservation is started, the oxygen valve is closed after the heat preservation time is over, and the temperature of the tube furnace is reduced;
closing the air exhaust valve and the mechanical pump when the temperature of the tube furnace is reduced to be below 500 ℃, opening the air exhaust valve after the pressure in the tube is restored to normal pressure, and inserting the air exhaust pipe into water; and when the temperature is cooled to be below 200 ℃, closing the tube furnace, the flow meter and the gas cylinder, and ending the experiment to obtain the MgZnO nanorod array layer.
4. Covering the electrode mask on the top of the grown MgZnO nanorod array layer, and fixing the periphery with an adhesive tape to prevent the conductive silver adhesive from escaping to the side of the sample to influence the test. Then use tweezers to press the mask gently, reduce its gap with the array top. Subsequently, the conductive silver paste was uniformly coated with a brush, the mask was removed and a platinum wire was connected to the coated conductive silver paste. And finally, placing the sample in an oven at 80 ℃ for standing for 30min to solidify the conductive silver adhesive, and finishing the preparation process to obtain the MgZnO nanorod array type ultraviolet detector with the cubic phase and the hexagonal phase mixed.
Example 3
An ultraviolet detector comprises the following preparation methods:
1. coating a piece of SiO with a thickness of 300nm2SiO of (2)2a/Si substrate.
2. Using Pulsed Laser Deposition (PLD) with Mg0.3Zn0.7O target material in SiO2On a Si substrate, growing a single hexagonal MgZnO film with the thickness of about 300nm on the condition that the oxygen pressure is 4.0Pa, the deposition time is 120-150 min, the oxygen flow is 10sccm, the base target spacing is 60mm, the laser energy is 300mJ, the laser frequency is 5Hz, and the substrate temperature is 400 ℃ to form a single hexagonal MgZnO seed crystal layer.
3. Obtaining zinc oxide, magnesium powder and carbon powder to carry out vapor deposition, and carrying out chemical vapor deposition by adopting a mode of an outer sleeve inner tube in a tube furnace, wherein the method specifically comprises the following steps:
firstly, as shown in figure 2, a mixture of 0.5g of zinc oxide and 0.5g of carbon powder, 0.2914g of magnesium powder and a substrate formed with a MgZnO seed crystal layer are placed in a small quartz tube inside, one section of the small quartz tube is closed, the other end of the small quartz tube is open, the open end of the small quartz tube is positioned at the downstream end of an air flow, then a short tube is slowly pushed into the quartz tube, the initial reactant is positioned at the heating center of a tube furnace, and a flange is installed;
and secondly, starting the tube furnace, the gas flow meter and the vacuum pump in sequence to vacuumize the quartz tube, and closing the vacuum pump when the pressure is lower than 2 torr. Subsequently opening respective O2Cleaning with Ar gas, recovering normal pressure, continuously vacuumizing and exhausting, and removing O2The gas is cleaned once, and the Ar gas is cleaned repeatedly for three times. Then adjusting the flow (30sccm) of the protector, opening a valve to exhaust when the normal pressure in the pipe is recovered, and treating tail gas in water;
setting the experiment heat preservation temperature of 900 ℃, the heat preservation time and the temperature rise and fall rate of 10 ℃/min and starting to heat;
when the temperature reaches the temperature near the temperature required by the reaction, taking the exhaust pipe out of the water, closing an exhaust valve, and then opening a vacuum pump to vacuumize to 2 torr;
adjusting O when the temperature reaches the preset temperature2The flow is 1.5sccm, the heat preservation is started, the oxygen valve is closed after the heat preservation time is over, and the temperature of the tube furnace is reduced;
closing the air exhaust valve and the mechanical pump when the temperature of the tube furnace is reduced to be below 500 ℃, opening the air exhaust valve after the pressure in the tube is restored to normal pressure, and inserting the air exhaust pipe into water; and when the temperature is cooled to be below 200 ℃, closing the tube furnace, the flow meter and the gas cylinder, and ending the experiment to obtain the MgZnO nanorod array layer.
4. Covering the electrode mask on the top of the grown MgZnO nanorod array layer, and fixing the periphery with an adhesive tape to prevent the conductive silver adhesive from escaping to the side of the sample to influence the test. Then use tweezers to press the mask gently, reduce its gap with the array top. Subsequently, the conductive silver paste was uniformly coated with a brush, the mask was removed and a platinum wire was connected to the coated conductive silver paste. And finally, placing the sample in an oven at 80 ℃ for standing for 30min to solidify the conductive silver adhesive, and finishing the preparation process to obtain the single hexagonal phase MgZnO nanorod array type ultraviolet detector.
Example 4
A MgZnO seed layer thin film was prepared in the same manner as the MgZnO seed layer thin film of example 1, except that the substrate deposition temperature was 500 ℃.
Comparative example 1
An ultraviolet detector comprises the following preparation methods:
1. coating a piece of SiO with a thickness of 300nm2SiO of (2)2a/Si substrate.
2. Using Pulsed Laser Deposition (PLD) with Mg0.3Zn0.7O target material in SiO2On a Si substrate, growing a cubic phase and hexagonal phase mixed MgZnO film on the conditions that the oxygen pressure is 4.0Pa, the deposition time is 120-150 min, the oxygen flow is 10sccm, the base target spacing is 60mm, the laser energy is 300mJ, the laser frequency is 5Hz, and the substrate temperature is 300 ℃, wherein the thickness of the film is about 300nm, and a cubic phase and hexagonal phase mixed MgZnO seed crystal layer is formed.
2. And covering the electrode mask on the top end of the MgZnO seed crystal layer, and fixing the periphery of the MgZnO seed crystal layer by using an adhesive tape to prevent the conductive silver adhesive from escaping to the side surface of the sample to influence the test. Then use tweezers to press the mask gently, reduce its gap with the array top. Subsequently, the conductive silver paste was uniformly coated with a brush, the mask was removed and a platinum wire was connected to the coated conductive silver paste. And finally, placing the sample in an oven at 80 ℃ for standing for 30min to solidify the conductive silver adhesive, and finishing the preparation process to obtain the ultraviolet detector of the MgZnO seed crystal layer with the cubic phase and the hexagonal phase mixed.
Further, in order to verify the progress of the ultraviolet detector and the preparation method thereof in the embodiments of the present application, the test examples of the present application characterize the oriented structure, morphology, Mg-doped content of the MgZnO nanorod array, the ultraviolet detection performance of the device, and the like of the ultraviolet detector prepared in embodiments 1 to 3 by means of an X-ray diffractometer (XRD), a field emission scanning electron microscope (FE-SEM), an X-ray energy spectrum analysis (EDS), and the like, and the specific test results are as follows:
test example 1
FIG. 4 is an XRD pattern of MgZnO nanorod arrays grown on MgZnO seed layer films of different phase structures in examples 1-3, in which the ordinate is intensity, the pattern (a) is a normal orientation intensity pattern, and the pattern (b) is a longitudinal axis orientation intensity logarithmic pattern (i.e. the original longitudinal axis value is logarithmic, which is convenient for observing details); wherein c-NRs are MgZnO nanorod arrays grown on the single cubic phase seed crystal layer in example 1, m-NRs are MgZnO nanorod arrays grown on the mixed cubic phase and hexagonal phase seed crystal layer in example 2, and h-NRs are MgZnO nanorod arrays grown on the single hexagonal phase seed crystal layer in example 1.
As can be seen from fig. 4: (1) the nanorod arrays successfully grow on the different-phase tissue seed layer films, and still have stronger (002) and (004) diffraction peaks, namely after 0.2914gMg raw material is doped, the nanorod arrays still have higher c-axis preferred orientation. (2) The (002) diffraction peak intensities of different MgZnO nanorod arrays have larger difference; nanorod arrays grown on single cubic and single hexagonal MgZnO film seed layers exhibit higher (002) orientation, while nanorod arrays grown on mixed phase MgZnO film seed layers exhibit poor (002) orientation.
Test example 2
FIG. 5 is an SEM image of MgZnO nanorod arrays grown on MgZnO seed layer films of different phase structures in examples 1-3. In which, diagrams (a) and (b) are MgZnO nanorod arrays grown with a single cubic phase seed layer of example 1, diagrams (c) and (d) are MgZnO nanorod arrays grown with a cubic phase and hexagonal phase mixed seed layer of example 2, and diagrams (e) and (f) are MgZnO nanorod arrays grown with a single hexagonal phase seed layer of example 3.
As can be seen from fig. 5: (1) the surfaces of the films of the seed crystal layers of different phase structures form a continuous MgZnO nanorod array with high orientation, large area and large length-diameter ratio, wherein the length of the nanorod is about 46 mu m, the diameter of the nanorod is about 200-300 nm. (2) The density of the nano rod surface on the surface of the different phase tissue seed crystal layer film has a certain difference, and the density of the MgZnO nano rod array surface grown on the surface of the single cubic phase seed crystal layer film is 5.8 multiplied by 107Root/cm2(58 roots/10. mu. m.times.10. mu. mm), the surface density of the MgZnO nanorod array grown on the surface of the mixed-phase seed crystal layer film is 4.9 multiplied by 107Root/cm2(49 roots/10 mu m multiplied by 10 mu m), the surface density of MgZnO nano-rod array grown on the surface of the single hexagonal phase seed crystal layer film is 7.3 multiplied by 10 mu m7Root/cm2(73 pieces/10. mu. m.times.10 μm). The MgZnO nanorod arrays grown on the surface of the mixed-phase seed crystal layer film are relatively low in density, the distances among nanorods are wide, and the MgZnO nanorod arrays can well promote the sufficient absorption of ultraviolet light.
Test example 3
FIG. 6 is a sectional EDS map of MgZnO nanorods arrays grown on thin films of different phase structure seed layers of examples 1-3, wherein (a) is the EDS map of example 1, (b) is the EDS map of example 2, and (c) is the EDS map of example 3. As can be seen from the figure: the Mg contents of the MgZnO nanorods grown on the single cubic phase seed crystal layer, the mixed phase seed crystal layer and the single hexagonal phase seed crystal layer are respectively 2.64 percent, 2.96 percent and 3.73 percent, which proves that the MgZnO nanorod array of the embodiment of the application is successfully doped with a certain content of Mg.
Test example 4
FIG. 7 shows the responsivity and the light-dark current ratio of the MgZnO nanorod array type UV detector grown on the MgZnO seed layer films with different phase structures in examples 1-3. In the attached figure 7, (a), (c) and (e) are responsivity graphs of the detectors of the embodiments 1-3 in sequence, the abscissa is wavelength, and the ordinate is responsivity. In the attached figure 7, (b), (d) and (f) are graphs of the light-dark current ratio results of the detectors of the embodiments 1-3 in sequence, wherein the abscissa is voltage, the left ordinate is current, and the right ordinate is the light-dark current ratio.
From the responsivity diagrams of FIGS. 7(a), (c), and (e): (1) the responsivity of all devices still increases with increasing bias voltage; (2) under the condition that the bias voltage is 5V, the responsivities of the MgZnO nanorod array type ultraviolet detector based on the single cubic phase MgZnO seed crystal layer film, the mixed phase MgZnO seed crystal layer film and the single hexagonal phase MgZnO seed crystal layer film respectively reach 13.51A/W, 51.94A/W and 29.75A/W, wherein the nanorod array type ultraviolet detector on the surface of the mixed phase tissue film has the highest responsivity; (3) the response peaks of the three devices mainly consist of a response peak of a MgZnO nanorod array at 365nm and a response peak of a MgZnO seed crystal layer film at 275 nm.
The light-dark current ratio results of FIGS. 7(b), (d), and (f) show that: as the bias voltage is increased from 1V to 5V, the photocurrents and dark currents of all the detectors show an increasing trend and reach the maximum value at the bias voltage of 5V; at this time, the maximum photocurrent values of the MgZnO nanorod array type ultraviolet detector based on the single cubic phase, mixed phase and single hexagonal phase MgZnO seed layer thin films were 2.80 × 10, respectively-6、8.79×10-6And 3.80X 10-6A; maximum dark current values of 4.41X 10, respectively-8、1.32×10-7And 1.86X 10-7A; the average light-to-dark current ratios were 120.62, 75.03, and 30.58, respectively.
In conclusion: the Mg-doped MgZnO nanorod arrays grown on the MgZnO seed crystal layer films with different phase structures in the embodiments 1-3 of the application all show the detection capability of ultraviolet light, wherein the MgZnO nanorod array type ultraviolet detector grown on the surface of the mixed-phase MgZnO seed crystal layer film has the best ultraviolet detection performance, and at the moment, the responsivity of the detector is 51.94A/W (corresponding to 5V bias voltage), and the average light-dark current ratio is 75.03. The diameter, the length and the like of the nanorods growing on the surfaces of MgZnO seed crystal layer films with different phase structures have no significant change, which shows that the difference of the performances of the nanorod array type ultraviolet detector is not influenced by the diameter and the length of the nanorods; in addition, the change range of the Mg content in the MgZnO nanorods growing on the surfaces of the MgZnO seed crystal layer films with different phase structures is only 2.64% -3.73%, namely the Mg doping amount is not changed obviously, so that the change of the Mg content in the MgZnO nanorods is not a main factor for changing the performance of the detector. Therefore, the difference of the area density of the embodiment of the application is crucial to the detection performance of the detector; compared with pure MgZnO seed crystal layer film with single cubic phase and single hexagonal phase, the surface of the MgZnO mixed phase seed crystal layer film can provide a moderate number of nucleation point positions, thereby obtaining MgZnO nano-rods (4.9 x 10) with moderate surface density7Root/cm2) And obtaining the optimum nanorod area density and finally obtaining the ultraviolet detector with the most excellent ultraviolet detection performance.
Test example 5
FIG. 8 is a graph (a) showing the responsivity of the MgZnO nanorod array UV detector grown from the mixed-phase MgZnO seed layer film of example 2, and a graph (b) showing the responsivity of the UV detector of comparative example 1, which contains only the mixed-phase MgZnO seed layer film.
The performance test of the attached drawings shows that: on one hand, under the voltage of 5V, the responsivity peak value of the thin film type detector in the comparative example 1 is 0.1A/W, while the responsivity peak value of the nanorod array type detector in the example 2 is 55A/W, and the responsivity of the array type detector is obviously improved compared with that of the thin film type detector. On the other hand, the response peak range of the thin film type detector in the comparative example 1 is about 250-300 nm, while the response peak range of the array type detector in the example 2 is about 270-370 nm, and compared with the response peak range of the array type detector in the example 2, the response peak range is greatly expanded.
Test example 6
FIG. 9 is an XRD pattern of the phase structure of MgZnO seed layer films deposited at substrate deposition temperatures of 200 deg.C, 300 deg.C, 400 deg.C and 500 deg.C, respectively, in examples 1-4, with intensity as ordinate. As shown in fig. 9, the diffraction peaks of the MgZnO seed layer thin film are located at 2 θ ═ 31.40 °, 34.87 °, 73.58 °, and 42.52 °, and belong to the hexagonal phase MgZnO (100), (002), (004), and cubic phase MgZnO (200) crystal planes, respectively. When the substrate deposition temperature is 200 ℃ and the growth temperature is lower, the solid solubility of Zn atoms in MgZnO is lower due to lower oxygen flow, and the formation of the MgZnO film with a single cubic phase (200) structure is promoted. As the substrate temperature increases from 200 ℃ to 500 ℃, a phase structure change tendency of "single cubic phase → mixed phase → single hexagonal phase" sequentially appears. When the substrate temperature is lower than 200 ℃, the MgZnO seed crystal layer films are all in hexagonal phase.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (10)

1. A preparation method of an ultraviolet detector is characterized by comprising the following steps:
obtaining a substrate layer, and depositing an MgZnO target on the substrate layer to form an MgZnO seed crystal layer;
growing MgZnO nanorods on the MgZnO seed crystal layer to form a MgZnO nanorod array layer;
and preparing an electrode on the surface of the MgZnO nanorod array layer, which is away from the MgZnO seed crystal layer, so as to obtain the ultraviolet detector.
2. The method of claim 1, wherein depositing the MgZnO target material on the substrate layer comprises: the molar ratio of Mg element to Zn element is 1: (0.43-2.33) under the conditions that the substrate temperature is 200-500 ℃, the oxygen pressure is 2-6 Pa, the oxygen flow is 8-12 sccm, the substrate-target distance is 40-80 mm, the laser energy is 200-400 mJ, and the laser frequency is 3-6 Hz, forming the MgZnO seed crystal layer.
3. The method for manufacturing an ultraviolet detector according to claim 2, wherein in the MgZnO seed layer, MgZnO crystals are in a cubic phase and/or a hexagonal phase; and/or
The MgZnO seed crystal layer is 200-500 nanometers thick.
4. The method for preparing the ultraviolet detector as claimed in any one of claims 1 to 3, wherein the step of growing MgZnO nanorods on the MgZnO seed layer comprises: the method comprises the steps of obtaining zinc oxide, magnesium powder and carbon powder, placing a mixture of the zinc oxide and the carbon powder, the magnesium powder and a substrate formed with a MgZnO seed crystal layer in a vapor deposition system, heating to 800-1000 ℃ under the conditions that the pressure is 2-3 torr and the flow of protective gas is 25-35 sccm, providing oxygen with the flow of 1-3 sccm, keeping the temperature for 20-40 min, cooling, and forming the MgZnO nanorod array layer on the surface of the MgZnO seed crystal layer, which deviates from the substrate.
5. The method for preparing the ultraviolet detector as claimed in claim 4, wherein the mass ratio of the zinc oxide, the carbon powder and the magnesium powder is 1: 1: (0.5 to 0.8); and/or
In the MgZnO nanorod array layer, the length of the MgZnO nanorod is 40-55 microns; the diameter of the MgZnO nano rod is 200 to 300 nanometers; and/or
In the MgZnO nanorod array layer, the areal density of the MgZnO nanorods is 4.9 multiplied by 107Root/cm2～7.3×107Root/cm2。
6. The method for manufacturing an ultraviolet detector as set forth in any one of claims 1 to 3 or 5, wherein the step of manufacturing an electrode comprises: two opposite metal electrodes are deposited on the surface of the MgZnO nanorod array layer, the length x the width of each metal electrode is (2-3) mm x (2-3) mm, and the distance between the metal electrodes is 0.5-2.5 mm.
7. The method of making an ultraviolet detector as set forth in claim 6, wherein the substrate layer is selected from the group consisting of: SiO 22One of a/Si substrate, a sapphire substrate and a quartz substrate.
8. The ultraviolet detector is characterized by comprising a substrate, a MgZnO seed crystal layer, a MgZnO nanorod array layer and an electrode which are sequentially stacked.
9. The ultraviolet detector of claim 8, wherein in the MgZnO nanorod array layer, the MgZnO nanorod array is perpendicular to the MgZnO seed layer; and/or
In the MgZnO nanorod array layer, the length of the MgZnO nanorod is 40-55 microns; the diameter of the MgZnO nano rod is 200 to 300 nanometers; and/or
In the MgZnO nanorod array layer, the areal density of the MgZnO nanorods is 4.9 multiplied by 107Root/cm2～7.3×107Root/cm2。
10. The ultraviolet detector according to claim 8 or 9, wherein the MgZnO seed layer has a thickness of 200 nm to 500 nm; and/or
In the MgZnO seed crystal layer, MgZnO crystals are cubic phase and/or hexagonal phase; and/or
The substrate layer is selected from: SiO 22One of a/Si substrate, a sapphire substrate and a quartz substrate.
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