CN110320678A - Terahertz wave modulator and preparation method thereof based on strontium titanates all dielectric Meta Materials - Google Patents
Terahertz wave modulator and preparation method thereof based on strontium titanates all dielectric Meta Materials Download PDFInfo
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- G—PHYSICS
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- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
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- G—PHYSICS
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- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
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Abstract
The present invention relates to the terahertz wave modulator and preparation method thereof based on strontium titanates all dielectric Meta Materials, terahertz wave modulator includes: polymer flexibility substrate layer；Doped semiconductor epitaxial layer: it is grown in polymer flexibility substrate layer surface；The SiO being grown on semiconductor silicon epitaxial layer2Insulation-strontium titanates micro-structure composite layer: it includes underlying SiO2Insulating layer, and it is grown in SiO2Strontium titanates microstructured layers on insulating layer.Compared with prior art, the quality factor of modulator obtained of the invention is high, tunable performance is good and modulation depth is big, and preparation process is relatively easy, is suitable for large-scale production application.
Description
Technical field
The invention belongs to photoelectric semiconductor materials and device arts, are related to a kind of based on strontium titanates all dielectric Meta Materials
Terahertz wave modulator and preparation method thereof.
Background technique
Terahertz (terahertz, THz) wave between microwave and infra-red radiation, is being in macroscopic view electricity in electromagnetic spectrum
Magnetic theory has bandwidth, transmission rate height, high directivity and safety height etc. all to the transitional region of Bcs Theory
More advantages all have broad prospects in basic research and practical application.For example, THz wave has frequency compared to microwave band
The features such as rate is high, signal bandwidth is big and high resolution, is suitable for ultra wide band, the superfast 5G communication technology, 0.12THz and
0.22THz is by as next-generation terrestrial wireless communication and intersatellite communication.Modulation technique and device are the passes of THz communication system
Key composition develops working and room temperature, compact-sized and brilliant performance modulator has the application development of promotion Terahertz Technology
Important meaning.People have carried out extensive research to THz modulation device in recent years, but still have many technical bottlenecks to need to solve.Example
If Quantum Well modulator need to work at low temperature, and liquid crystal modulator is temperature sensitive, loss is larger, modulating speed is slower
(KHz), and frequency-tuning range is smaller (liquid crystal material is lower in the birefringence of THz wave band).
Meta Materials (Metamaterials, MMs) are also known as " superstructure ", " anisotropic media " or " special electromagnetic medium ", are
Pass through artificial or the composite material structure system with period or quasi-periodic structure and special electromagnetic property of synthesis.MMs
New electromagnetic response medium is formed using artificial resonance cell element (unit cell, meta-molecular), and there is natural material institute
The abnormal physical characteristic not having, such as negative magnetoconductivity, negative electricity conductance.The property and function of Meta Materials depend primarily on sub-wavelength
The geometry and its spatial distribution of structural unit can design different and natural medium physical property according to actual needs
Function material component.Meta Materials modulation device is usually made of metal material, is lost mainly from the ohmic loss for constituting material
With the radiation loss of resonating member；In addition the wavelength of THz wave is longer, the structural unit of sub-wavelength dimensions be difficult to THz wave into
Row effectively constraint.Therefore, quality factor (Q-factor) value of THz band modulators is not generally high (< 5), largely
Development and application of the THz Meta Materials modulator in terms of numerous areas is limited, such as the sensing capability of sensor, the filtering of filter
Characteristic and resolution capability etc..To meet in numerous practical application areas such as waveform control, biological sample analysis and wireless telecommunications
Demand, there is an urgent need to develop the tunable THz modulation device that modulation depth is big, modulating speed is fast and quality factor is high.
Meta Materials mostly use greatly metal material to be designed and process preparation at present, although excellent with forming easy to process
Gesture, but there are high temperature ablation, high-frequency loss is big and the problems such as power carrying is small.Metal MMs relies primarily on the conduction on surface
Electric current realizes the regulation to wave frequency selection characteristic, but according to Maxwell equation displacement current under the action of incidence wave
Also there is similar functions effect.If incident wavelength matches with structure size, the super material of all dielectric of high dielectric constant (Si, Ge)
Material (all-dielectric metamaterials, ADMs) can excite resonance very strong under the action of being powered on magnetic wave outside
Displacement current forms so-called Mie resonance.Mie similar to the LC resonance and dipole resonance in metal Meta Materials, in ADMs
Resonance also can produce equivalent electric dipole and magnetic dipole, and can to avoid the dispersion absorption of metal and energy loss,
Facilitate the raising of quality factor.All dielectric material is also easier to process thicker micro-structure, in the propagation direction phase controlling
It is higher than metal structure, the phase-modulation of 2 π easy to accomplish and the control of efficient wavefront in terms of ability.In short, super compared to metal
Material structure, the displacement current in ADMs are lost very little, help to obtain the resonance line of narrowband, high-quality-factor, can be with
Support a variety of resonance modes such as electric dipole, magnetic dipole and multipole sub-resonance, for THz tunable devices development provide it is good
Good design platform and flexile adjusting method.
Chinese patent ZL201310547214.6 discloses a kind of Terahertz modulator based on ferroelectric thin film and its production
Method.The Terahertz modulator includes: medium substrate, to THz wave transmitance with higher；Multiple ferroelectric thin films
Unit, array arrangement is on the medium substrate；Terahertz filter structure is arranged in the medium substrate and the multiple ferroelectricity
On film unit.The patent, as medium is adjusted, realizes the modulation to incident THz by electric-control method using full wafer strontium titanates,
When applying bias is adjusted within the scope of 0-10V, amplitude modulation depth is 21%, and depth of frequency modulation is about 3.8%, width
It is worth modulation depth and depth of frequency modulation is shallower.
Summary of the invention
It is complete based on strontium titanates that it is an object of the present invention to overcome the above-mentioned drawbacks of the prior art and provide one kind
The terahertz wave modulator and preparation method thereof of medium Meta Materials.
The purpose of the present invention can be achieved through the following technical solutions:
One of technical solution of the present invention is the provision of a kind of THz wave tune based on strontium titanates all dielectric Meta Materials
Device processed, comprising:
Polymer flexibility substrate layer；
Doped semiconductor epitaxial layer: it is grown in polymer flexibility substrate layer surface；
The SiO being grown on semiconductor silicon epitaxial layer2Insulation-strontium titanates micro-structure composite layer: it includes underlying
SiO2Insulating layer, and it is grown in SiO2Strontium titanates microstructured layers on insulating layer.
Further, the polymer flexibility substrate layer is made of plastic flexible substrate solution, with a thickness of 1-50 μm.
Further, the polymer flexibility substrate layer with a thickness of 2-10 μm.
Further, the doped semiconductor epitaxial layer is Si layers, and with a thickness of 1-10 μm, charge-carrier dopant concentration is
1015-1018cm-3, conductivity is 1-10 Ω cm.Further, the doped semiconductor epitaxial layer with a thickness of 1-5 μ
M, doping concentration are 1 × 1016-5×1016cm-3。
Further, the SiO2Insulating layer with a thickness of 10-100nm, strontium titanates microstructured layers with a thickness of 1-5 μ
m.Further, with a thickness of 10-50nm.
Further, strontium titanates microstructured layers are oval.Incidence wave polarization direction along oval major semiaxis direction.
Further, the preparation method of strontium titanates microstructured layers can refer to the sol-gal process in technical solution two.
The two of technical solution of the present invention are the provision of a kind of preparation side of THz modulator based on strontium titanates micro-structure
Method, comprising the following steps:
(1) polymer flexibility substrate layer is made:
Using common Si as sacrificial layer, by the solution spraying containing plastic flexible substrate on sacrificial layer, after baking and curing,
Obtain polymer flexibility substrate layer；
(2) doped semiconductor epitaxial layer is made:
Doped semiconductor epitaxial layer is formed on polymer flexibility substrate layer by epitaxial growth method；
(3) SiO is made2Insulation-strontium titanates micro-structure composite layer:
(3-1) atomic layer deposition SiO on doped semiconductor epitaxial layer2, rinse well, SiO be made2Insulating layer；
(3-2) is in SiO2Strontium titanate film is deposited on insulating layer, then heating anneal completes crystallisation procedure, and eliminates and lack
It falls into；
(3-3) removes the strontium titanates of redundance, forms strontium titanates microstructured layers；
(4) removing sacrificial layer is to get to the strontium titanates micro-structure THz modulator on polymer flexibility substrate layer.
Further, in step (1), the process conditions of drying are as follows: the dry 20-40min in 150-200 DEG C, it is cured
Process conditions are as follows: be heated to 300-400 DEG C under inert gas protection.
Further, in step (3-1), atomic layer deposition SiO2Temperature be 180-220 DEG C.
Further, in step (3-2): the annealing temperature of strontium titanate film is 600-1200 DEG C, and the time is 2-4 hours.
Further, in step (3-2): the annealing temperature of strontium titanate film is 800-1000 DEG C.
Further, the deposition method of strontium titanate film is sol-gal process or magnetron sputtering method, wherein sol-gal process
Process specifically:
(a) first strontium acetate being taken to be dissolved in acetum, and is heated to boiling, heat preservation is cooled to room temperature after 15 minutes, then
Addition is dissolved in the solution of tetrabutyl titanate in 2,4- pentanedione, stirs evenly, and is subsequently added into acetic acid adjusting, retains spare；
(b) it takes the solution of step (a) preparation and doped semiconductor epi-layer surface is deposited to using spin spraying method, dry
After dry, heating, the strontium titanate film of removal organic impurities is obtained；
Further, in sol-gal process, in step (a), the molar ratio of the additive amount of barium acetate and butyl titanate
For 1:1, the equal 0.3M of the concentration of strontium acetate and butyl titanate；
In step (b), the temperature of drying is 250 DEG C, drying time 5min, and heating temperature is 500 DEG C, and heating time is
10min；
Compared to the conduction electric current in metal, the displacement current in strontium titanates dielectric layer is weaker, it is therefore desirable to thicker ruler
Degree (general 100 nanometers of the thickness of metal layer) significantly resonates to have excited, but if strontium titanates thickness is too big, it not only can band
Come the difficulty prepared, while loss also will increase, therefore we choose 1-5 μm.SiO2Thickness of insulating layer is too big, for transmission
Type modulator is unfavorable, can reduce transmissivity and modulating performance.Ellipse micro-structure why is selected, is on the one hand due in reality
Circular microstructure is difficult to realize since error exists in process；On the other hand really play main function along incidence wave
The macro structural scale of polarization direction can obtain better excitation using ellipse micro-structure in the case where same sample area
Effect, resonance line are more obvious.
THz modulation working principle produced by the present invention based on strontium titanates ellipse micro-structure is as follows:
After incident THz wave and strontium titanates ellipse microstructure Modulation device, since strontium titanates dielectric constant is higher, formed stronger
Displacement current, generate apparent resonance line.Wherein, the photoelectric characteristic of strontium titanates micro-structure can be changed by temperature and is subject to
It adjusts.When temperature is lower, such as 70K, strontium titanates dielectric constant is higher, and resonance response is stronger；As the temperature rises, such as 300K,
Strontium titanates dielectric constant reduces, and resonance response reduces, and the resonant frequency of spectral line and amplitude are different with the change of temperature.
Compared with prior art, the invention has the following advantages that
(1) compared to traditional full wafer strontium titanates, the present invention uses strontium titanates ellipse micro-structure, when the polarization of incidence wave
When direction is along major semiaxis, the apparent resonance line that can be formed, by suitably adjusting temperature, thus it is possible to vary resonance spectrum
The waveform of line；
(2) present invention uses strontium titanates metamaterial structure, based on this asymmetrical micro-structure of ellipse, by change into
Ejected wave polarization direction can easily realize the adjusting to resonance line waveform and amplitude；
(3) present invention to the scantling of flexible substrate, thickness of back electrode semiconductor layer etc. can also select excellent
Change, to further obtain biggish modulation depth and lower loss；
(4) quality factor of last obtained modulator is high, tunable performance is good and modulation depth (amplitude modulation depth is big greatly
In 90%).
(5) preparation process is relatively easy, is suitable for large-scale production application.
Detailed description of the invention
Fig. 1 is that the present invention is based on the humorous temperature control high-quality-factor THz modulation of ferroelectric material strontium titanates ellipse microfabricated tunable
Device schematic illustration；
Fig. 2 is that the present invention is based on the vertical views of the THz modulator structure schematic diagram of ferroelectric material strontium titanates ellipse micro-structure
Figure；
Fig. 3 is that the present invention is based on the temperature control principle schematic diagrames of ferroelectric material strontium titanates ellipse microstructure Modulation device；
Fig. 4 is the analog result figure of the invention based on ferroelectric material strontium titanates ellipse micro-structure THz modulation device, temperature
Spend the influence to resonance line；
Fig. 5 is the analog result figure of the invention based on ferroelectric material strontium titanates ellipse micro-structure THz modulation device, is entered
Influence of the ejected wave difference polarisation angles to resonance line waveform；
Fig. 6 is the resonance line quality factor and Optimization Factor of the THz modulation device based on strontium titanates ellipse micro-structure
Analog result；
In figure, 1- polymer flexibility substrate layer, 2- doped semiconductor epitaxial layer, 3-SiO2Insulating layer, the micro- knot of 4- strontium titanates
Structure layer.
Specific embodiment
The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.The present embodiment is with technical solution of the present invention
Premised on implemented, the detailed implementation method and specific operation process are given, but protection scope of the present invention is not limited to
Following embodiments.
In one of technical solution of the present invention, a kind of THz wave modulation based on strontium titanates all dielectric Meta Materials is proposed
Device, comprising:
Polymer flexibility substrate layer 1；
Doped semiconductor epitaxial layer 2: being grown in polymer flexibility substrate layer surface, and insulating properties is preferable, reduces damage to reach
The purpose of consumption；
The SiO being grown on semiconductor silicon epitaxial layer2Insulation-strontium titanates micro-structure composite layer: it includes underlying
SiO2Insulating layer 3, and it is grown in SiO2Strontium titanates microstructured layers 4 on insulating layer 3.
In a kind of specific embodiment of the invention, polymer flexibility substrate layer is by plastic flexible substrate solution system
At, with a thickness of 1-50 μm, preferably 2-10 μm.
In a kind of specific embodiment of the invention, the doped semiconductor epitaxial layer is Si layers, with a thickness of
1-10 μm, charge-carrier dopant concentration is 1015-1018cm-3, conductivity is 1-10 Ω cm.Further, the doping half
Conductor epitaxial layer with a thickness of 1-5 μm, doping concentration 1016-5×1016cm-3。
In a kind of specific embodiment of the invention, the SiO2Insulating layer with a thickness of 10-100nm, metatitanic acid
Strontium microstructured layers with a thickness of 1-5 μm.Further, with a thickness of 10-50nm.
In a kind of specific embodiment of the invention, strontium titanates microstructured layers are oval.
In a kind of specific embodiment of the invention, the preparation method of strontium titanates microstructured layers can refer to below molten
Sol-gel.
In the two of technical solution of the present invention, a kind of preparation side of THz modulator based on strontium titanates micro-structure is provided
Method, comprising the following steps:
(1) polymer flexibility substrate layer is made:
Using common Si as sacrificial layer, by the solution spraying containing plastic flexible substrate on sacrificial layer, after baking and curing,
Obtain polymer flexibility substrate layer；
(2) doped semiconductor epitaxial layer is made:
Doped semiconductor epitaxial layer is formed on polymer flexibility substrate layer by epitaxial growth method；
(3) SiO is made2Insulation-strontium titanates micro-structure composite layer:
(3-1) atomic layer deposition SiO on doped semiconductor epitaxial layer2, rinse well, SiO be made2Insulating layer；
(3-2) is in SiO2Strontium titanate film is deposited on insulating layer, then heating anneal completes crystallisation procedure, and eliminates and lack
It falls into；
(3-3) removes the strontium titanates of redundance, forms strontium titanates microstructured layers；
(4) removing sacrificial layer is to get to the strontium titanates micro-structure THz modulator on polymer flexibility substrate layer.
In a wherein specific embodiment, in step (1), the process conditions of drying are as follows: done in 150-200 DEG C
Dry 20-40min, cured process conditions are as follows: be heated to 300-400 DEG C under inert gas protection.
In wherein another specific embodiment, in step (3-1), atomic layer deposition SiO2Temperature be 180-
220℃。
In wherein another specific embodiment, in step (3-2): the annealing temperature of strontium titanate film is 600-
1200 DEG C, the time is 2-4 hours.
Further, in step (3-2): the annealing temperature of strontium titanate film is 800-1000 DEG C.
In wherein another specific embodiment, the deposition method of strontium titanate film is that sol-gal process or magnetic control splash
Penetrate method, wherein the process of sol-gal process specifically:
(a) first strontium acetate being taken to be dissolved in acetum, and is heated to boiling, heat preservation is cooled to room temperature after 15 minutes, then
Addition is dissolved in the solution of tetrabutyl titanate in 2,4- pentanedione, stirs evenly, and is subsequently added into acetic acid and is adjusted to (strontium acetate and titanium
The total concentration of sour four butyl esters is 0.3M, is retained spare；
(b) it takes the solution of step (a) preparation and doped semiconductor epi-layer surface is deposited to using spin spraying method, dry
After dry, heating, the strontium titanate film of removal organic impurities is obtained；
The detailed process of magnetron sputtering method are as follows: with SrTiO3Magnetron sputtering is carried out as target, when sputtering is passed through indifferent gas
Body Ar and O2Composed mixed gas.
Further, in sol-gal process, in step (a), the ratio between additive amount of barium acetate and butyl titanate is (to ask
Specific additive amount range is supplemented, and is clearly mass ratio, molar ratio or other ratios),
In step (b), the temperature of drying is 250 DEG C, drying time 5min, and heating temperature is 500 DEG C, and heating time is
10min。
Above embodiment of the present invention is further described in detail below in conjunction with specific embodiment.
Embodiment 1:
A kind of THz modulator based on strontium titanate base ellipse micro-structure, comprising:
Polymer flexibility substrate layer；
Semiconductor epitaxial layers: Si layers of doped semiconductor formed by epitaxial growth method, insulating properties is preferable, to reach drop
Low-loss purpose；
SiO2Insulation-strontium titanates micro-structure composite layer: being grown on semiconductor Si epitaxial layer, by a SiO2Insulation-metatitanic acid
The structural unit of strontium microstructured layers forms, and specifically includes underlying SiO2Insulating layer, and it is grown in SiO2On insulating layer
Strontium titanates microstructured layers.
In the present embodiment, polymer flexibility substrate layer is made of plastic flexible substrate solution, such as polyimide, thickness
It is 50 μm；Doped semiconductor epitaxial layer is Si layers of doping, and with a thickness of 10 μm, charge-carrier dopant concentration is 1018cm-3, conductivity
For 10 Ω cm, the common semiconductors such as diffusion and ion implanting doping method reality can be passed through by adulterating the carrier concentration in Si layers
Now and determine.
SiO2Insulation-strontium titanates micro-structure composite layer is by SiO2Insulation-strontium titanates ellipse microstructured layers are constituted.This structure
SiO2The modulation depth and speed of modulation waveform can be improved in insulation-active area structure composite layer.SiO2Insulating layer with a thickness of
30nm or so, strontium titanates microstructured layers are oval, with a thickness of 2-5 μm or so.
Embodiment 2
Present embodiments provide a kind of preparation work of the high-quality-factor THz modulator of strontium titanate base ellipse micro-structure
Skill, specifically includes the following steps:
(1) it makes polymer flexibility substrate layer: using common Si piece as sacrificial layer, (spincoated) being sprayed by spin
Method by the solution spraying containing plastic polymer flexible substrate layer above, then in an oven dry 30 minutes or so,
Temperature range is at 150-200 DEG C or so (preferably 180 DEG C or so), then using high temperature furnace in inert gas (or N2) protection
It is heated to 300-400 DEG C (preferably 350 DEG C) in atmosphere, forms uniform polymer flexibility substrate layer；
(2) make doped semiconductor epitaxial layer: forming 1-10 μ m thick by epitaxial growth method (can be 1 μm, 5 μm
Or 10 μm, the present embodiment is preferably 5 μm or so) semiconductor Si epitaxial layer, doping concentration be 3 × 1016cm-3, Si layers of conductivity
For 1-10 Ω cm, insulating properties is preferable, to reach the low-loss purpose of drop；
(3) SiO is formed on Si buffer layer using technique for atomic layer deposition2Insulating layer, optimum thickness are about 60-80nm,
Formation temperature is 200 DEG C, then clean with distilled water flushing；
(4) strontium titanates solution is prepared by sol-gel method: by strontium acetate (Sr (CH3COO)2) it is dissolved in acetum
In, controlling its molar concentration is 0.6mol/L, and is heated to boiling, and heat preservation is cooled to room temperature after 15 minutes；
(5) by butyl titanate (Ti (OC4H9)4) it is dissolved in 2,4- pentanedione (CH3COCH2COCH3) in solution, control it
Molar concentration is 0.6mol/L, is added in the solution in step (4), reacts to obtain strontium titanates solution (i.e. STO solution)；
(6) strontium titanate film is prepared by the method for spin spraying: added into STO solution obtained in above-mentioned steps (5)
Enter acetic acid, until solute strontium acetate and butyl titanate are diluted to 0.3mol/L, is deposited on by the method for spin spraying outer
Prolong the surface Si, the revolving speed for spraying of spinning is 3000rpm, time 20s；
(7) the STO film for obtaining step (6) is dried, and drying temperature is 250 DEG C, the time 5 minutes；It is heated to 500 DEG C simultaneously
Heat preservation 10 minutes, to remove remnant organic matter.
(8) above-mentioned (6) and (7) two processes are repeated, STO film is obtained, until film thickness is about 2-5 μm.
(9) STO film heating is annealed, temperature is 600-1200 DEG C, and keeps the temperature 3-5 hour, completes the crystallization of STO
Process, while reducing the internal flaw of film.
(10) using processes such as photoetching or plasma etchings, extra strontium titanates is removed, ellipse is obtained
Strontium titanates microstructured layers.
(11) the Terahertz strontium titanates microstructure Modulation device that above-mentioned technical process obtains is cleaned up using distilled water, 3-
5 times or more, then (Ar or N under protective atmosphere2) in the clean drying of purging.
(12) it will be removed, be obtained in polymer flexible from Si substrate based on strontium titanates ellipse micro-structure Terahertz modulator
Strontium titanate film tunable devices on property substrate layer.
Fig. 1 be the present invention is based on the schematic illustration of the THz modulator of strontium titanates ellipse micro-structure, incident THz wave with
Strontium titanates ellipse microstructure unit modulator interacts, and forms strong resonance line.Wherein, strontium titanates micro-structure
Layer 4 is used as tunable dielectric layer, and dielectric constant can be adjusted by changing temperature.As shown in Figure 1, when temperature is lower
When, such as 70K, strontium titanates dielectric constant with higher, by displacement current generate strontium titanate layer resonance characteristics it is significant；Conversely,
When temperature is higher, strontium titanates dielectric constant is lower, and resonance characteristics is weaker, while the position for paddy of resonating also can be with the change of temperature
And it is different.
Fig. 2 is that the present invention is based on the top view of strontium titanates ellipse micro-structure THz modulator structure schematic diagram, a thereinx
And ayFor the semi-minor axis and major semiaxis of strontium titanates ellipse micro-structure, pxAnd pyIt is strontium titanates ellipse micro-structure along the direction x
With the cycle length in the direction y, Hx indicates that the magnetic direction of incidence wave is the direction x, and Ey is that the direction of an electric field of incidence wave is the direction y.
Fig. 3 is the temperature control principle schematic diagram of strontium titanates ellipse type micro-structure Terahertz modulator of the present invention, and heater is put
It sets on strontium titanates surface.External circuits closure switch, heating lamp light, and strontium titanates micro-structure temperature under heater is able to
Change.All-in resistance in circuit is adjusted by slide rheostat and variable rheostat, to change the size of current in circuit, is realized different
Heating work under power.Meanwhile the real-time temperature values of strontium titanates can be monitored by temperature indicator.For example, when resistance compared with
Hour (such as R1), electric current is larger in circuit, and heating power is larger, at this time higher (such as T of strontium titanates temperature1), dielectric constant is lower
ε1；Conversely, (such as R when resistance is larger2), electric current is smaller in circuit, and heating power is smaller, and strontium titanates temperature is lower (such as at this time
T2), the lower ε of dielectric constant2。
Fig. 4 is the simulation knot of the THz modulation device based on strontium titanates ellipse micro-structure made from the embodiment of the present invention 2
Fruit；The semi-minor axis of ellipse micro-structure and the length of major semiaxis are respectively 15 μm and 60 μm in figure.When temperature is between 70-300K
(in figure, along initial position toward right direction, it is 70K-300K that five curves, which respectively represent temperature), paddy of resonating in the case where adjusting
Depth of frequency modulation is 21.9%, and amplitude modulation depth is 95.6%, wherein the definition of amplitude modulation depth is (Tmax-Tmin)/
Tmax, TmaxAnd TminThe respectively maximum value and minimum value of transmission spectral line resonance valley.Depth of frequency modulation is defined as: (fmax-
fmin)/fmax, fmaxAnd fminRespectively transmit the maximum value and minimum value of spectral line resonant frequency.
Fig. 5 is the resonance line of the THz modulation device based on strontium titanates ellipse micro-structure made from the embodiment of the present invention 2
Analog result；The semi-minor axis of ellipse micro-structure and the length of major semiaxis are respectively 15 μm and 60 μm in figure.When in such as Fig. 5 frame
Shown in small figure, θ is incidence wave wave vector k0Relative to surface normal direction angle (in figure, along initial position toward right direction, five
It is 0-89degree that curve, which respectively represents angle, θ), φ is angle of the incidence wave polarization direction relative to y-axis.In vertical incidence
In the case of, if polarisation angles φ changes between 0-90 degree, the amplitude modulation depth for the valley that resonates can achieve 89.2%.From
When Fig. 5 can be seen that change incidence wave angle, variation of resonant frequency is little, but can produce a very large impact to waveform,
Amplitude modulation depth can achieve 89%, in the case of not changing sample structure parameter, by the polarization side for changing incidence wave
To may be implemented to incidence wave waveform regulate and control.
Fig. 6 is the resonance line quality factor and Optimization Factor of the THz modulation device based on strontium titanates ellipse micro-structure
Analog result；The semi-minor axis of ellipse micro-structure and the length of major semiaxis are respectively 15 μm and 60 μm in figure.When in such as Fig. 5 frame
Shown in small figure, θ is incidence wave wave vector k0Relative to surface normal direction angle (in figure, along initial position toward right direction, five
It is 0-89 degree that curve, which respectively represents angle φ), φ is angle of the incidence wave polarization direction relative to y-axis.In the feelings of vertical incidence
Under condition, in the case that polarisation angles φ is respectively 0 degree, 30 degree, 60 degree and 75 degree, the quality factor of resonance line is respectively
5.575,6.514,13.36 and 20.39, as shown in fig. 6, quality factor q is defined as: Q=fres/ FWHW, fresFor resonance frequency
Rate, FWHW (full width at half maximum) are the halfwidth of spectral line.
In embodiment of submitting a written statement to a higher authority, each structure sheaf and process conditions can arbitrarily adjust in following range, these are not
The acquisition of the terahertz wave modulator of the invention based on strontium titanates all dielectric Meta Materials is influenced, specifically:
The process conditions of plastic flexible substrate solution drying are that can arbitrarily select in following range: at 150-200 DEG C
Interior dry 20-40min；Equally, cured process conditions can also arbitrarily select in following range: under inert gas protection
It is heated to 300-400 DEG C；
Atomic layer deposition SiO2Temperature can replace with 180 DEG C, 220 DEG C etc. respectively.
The annealing temperature of strontium titanate film can in following range arbitrarily select: 600-1200 DEG C (such as 600,800,
900,1000,1200), arbitrarily select preferably in following range: 800-1000 DEG C, soaking time is or so 2-4 hour.
In addition, the polymer flexibility substrate layer thickness finally obtained can arbitrarily select 1-50 μm in following range；
Doped semiconductor epitaxial layer can arbitrarily select in following specification limit: 1-10 μm of thickness, charge-carrier dopant is dense
Degree is 1015-1018cm-3, conductivity is 1-10 Ω cm.
SiO2The thickness of insulating layer can arbitrarily select in following specification limit: 10-100nm, strontium titanates microstructured layers
Thickness can in following specification limit arbitrarily select: 1-5 μm.
The above description of the embodiments is intended to facilitate ordinary skill in the art to understand and use the invention.
Person skilled in the art obviously easily can make various modifications to these embodiments, and described herein general
Principle is applied in other embodiments without having to go through creative labor.Therefore, the present invention is not limited to the above embodiments, ability
Field technique personnel announcement according to the present invention, improvement and modification made without departing from the scope of the present invention all should be of the invention
Within protection scope.
Claims (10)
1. a kind of terahertz wave modulator based on strontium titanates all dielectric Meta Materials characterized by comprising
Polymer flexibility substrate layer；
Doped semiconductor epitaxial layer: it is grown in polymer flexibility substrate layer surface；
The SiO being grown on semiconductor silicon epitaxial layer2Insulation-strontium titanates micro-structure composite layer: it includes underlying SiO2Absolutely
Edge layer, and it is grown in SiO2Strontium titanates microstructured layers on insulating layer.
2. a kind of terahertz wave modulator based on strontium titanates all dielectric Meta Materials according to claim 1, feature exist
In the polymer flexibility substrate layer is made of plastic flexible substrate solution, with a thickness of 1-50 μm；
The doped semiconductor epitaxial layer is Si layers, and with a thickness of 1-10 μm, charge-carrier dopant concentration is 1015-1018cm-3,
Conductivity is 1-10 Ω cm.
3. a kind of terahertz wave modulator based on strontium titanates all dielectric Meta Materials according to claim 2, feature exist
In, the polymer flexibility substrate layer with a thickness of 2-10 μm；
The doped semiconductor epitaxial layer with a thickness of 1-5 μm, doping concentration 1016-5×1016cm-3。
4. a kind of terahertz wave modulator based on strontium titanates all dielectric Meta Materials according to claim 1, feature exist
In the SiO2Insulating layer with a thickness of 10-100nm, strontium titanates microstructured layers with a thickness of 1-5 μm.
5. a kind of terahertz wave modulator based on strontium titanates all dielectric Meta Materials according to claim 1, feature exist
In strontium titanates microstructured layers are oval.
6. a kind of preparation method of THz modulator based on strontium titanates micro-structure a method as claimed in any one of claims 1 to 5, feature
It is, comprising the following steps:
(1) polymer flexibility substrate layer is made:
Using common Si as sacrificial layer, by the solution spraying containing plastic flexible substrate on sacrificial layer, after baking and curing, obtain
Polymer flexibility substrate layer；
(2) doped semiconductor epitaxial layer is made:
Doped semiconductor epitaxial layer is formed on polymer flexibility substrate layer by epitaxial growth method；
(3) SiO is made2Insulation-strontium titanates micro-structure composite layer:
(3-1) atomic layer deposition SiO on doped semiconductor epitaxial layer2, rinse well, SiO be made2Insulating layer；
(3-2) is in SiO2Strontium titanate film is deposited on insulating layer, then heating anneal completes crystallisation procedure, and eliminates defect；
(3-3) removes the strontium titanates of redundance, forms strontium titanates microstructured layers；
(4) removing sacrificial layer is to get to the strontium titanates micro-structure THz modulator on polymer flexibility substrate layer.
7. a kind of preparation method of THz modulator based on strontium titanates micro-structure according to claim 6, feature exist
In, in step (1), the process conditions of drying are as follows: dry 20-40min, cured process conditions are as follows: lazy in 150-200 DEG C
300-400 DEG C is heated under property gas shield；
In step (3-1), atomic layer deposition SiO2Temperature be 180-220 DEG C；
In step (3-2): the annealing temperature of strontium titanate film is 600-1200 DEG C, and the time is 2-4 hours.
8. a kind of preparation method of THz modulator based on strontium titanates micro-structure according to claim 7, feature exist
In in step (3-2): the annealing temperature of strontium titanate film is 800-1000 DEG C.
9. a kind of preparation method of THz modulator based on strontium titanates micro-structure according to claim 6, feature exist
In the deposition method of strontium titanate film is sol-gal process or magnetron sputtering method, wherein the process of sol-gal process specifically:
(a) first strontium acetate is taken to be dissolved in acetum, and is heated to boiling, heat preservation is cooled to room temperature after 15 minutes, is added
The solution of tetrabutyl titanate being dissolved in 2,4- pentanedione, stirs evenly, and is subsequently added into acetic acid adjusting, retains spare；
(b) it takes the solution of step (a) preparation and doped semiconductor epi-layer surface is deposited to using spin spraying method, dry,
After heating, the strontium titanate film of removal organic impurities is obtained.
10. a kind of preparation method of THz modulator based on strontium titanates micro-structure according to claim 9, feature exist
In, in sol-gal process, in step (a), the ratio between additive amount of barium acetate and butyl titanate is 1:1,
In step (b), the temperature of drying is 250 DEG C, drying time 5min, and heating temperature is 500 DEG C, and heating time is
10min。
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