CN102290478B

CN102290478B - A kind of p-i-n type unijunction InGaN solar cell

Info

Publication number: CN102290478B
Application number: CN201110259810.5A
Authority: CN
Inventors: 刘如彬; 孙强; 张启明; 王帅; 康培; 高鹏; 穆杰
Original assignee: CETC 18 Research Institute
Current assignee: CETC 18 Research Institute
Priority date: 2011-09-05
Filing date: 2011-09-05
Publication date: 2016-03-09
Anticipated expiration: 2031-09-05
Also published as: CN102290478A

Abstract

The present invention relates to a kind of p-i-n type unijunction InGaN solar cell, comprise a substrate, it is followed successively by GaN nucleating layer, GaN resilient coating, the n-GaN layer of Si doping and the p-GaN layer of Mg doping, is characterized in: on the n-GaN layer of Si doping, growth has i-In _xga _1-xn layer, above the p-GaN layer of Mg doping, evaporation has translucent current extending, and evaporation has positive electrode, and above the n-GaN layer of Si doping, evaporation has negative electrode.The present invention adopts ripe growth technique, and the n-GaN layer of Si doping grows unadulterated i-In _xga _1-xn layer, improves photoelectric conversion efficiency, relative to quantum dot or quantum well structure, is easy to preparation; By the translucent current extending of evaporation and positive and negative electrode, achieve the direct application of complete solar cell, and further increase capability of resistance to radiation, extend the useful life of battery.

Description

A kind of p-i-n type unijunction InGaN solar cell

Technical field

The invention belongs to solar battery structure technical field, particularly relate to a kind of p-i-n type unijunction InGaN solar cell.

Background technology

Along with the energy crisis of global range and going from bad to worse of ecological environment problem, people more and more pay attention to this inexhaustible green energy resource of solar energy, and for a long time, people are finding the material of high conversion efficiency diligently.In recent years, third generation semi-conducting material GaN and InGaN, AlGaN are III group-III nitride of representative is the focus that people study, and it is mainly used in photoelectric device and high temperature, high frequency, high power device.The result of study of 2002 shows, the energy gap of InN be not before the 1.89eV of report but 0.7eV, this just means by regulating In component in InGaN material, its energy gap can be made from the 0.7eV continuously adjustabe of 3.4eV to the InN of GaN, the wavelength of its corresponding absorption spectrum can extend to the infrared part of nearly 1770nm from the ultraviolet portion of 365nm, almost intactly cover whole solar spectrum, so the application of InGaN material in area of solar cell causes the close attention of people.

Except wave-length coverage is mated well with solar spectrum, InGaN material is compared with conventional solar cell material, also have the following advantages: first, it is direct band gap material, its absorption coefficient one, two order of magnitude higher than GaAs, Si, it is thinner, lighter that this just means that InGaN solar cell can do, thus cost-saving, especially has great significance for AEROSPACE APPLICATION; The electron mobility of the second, InN and GaN is all higher, is conducive to reducing compound, thus improves the short circuit current of solar cell; The capability of resistance to radiation of the three, InGaN material is stronger than solar cell materials such as Si, GaAs, is more suitable for being applied to strong radiation environment.Theory calculate shows, the highest theoretical conversion efficiencies of InGaN unijunction solar cell is 27.3%, higher than the theoretical value of Si or GaAs single junction cell.

Find that the patent No. is 200510098734.9 through retrieval, name is called: a kind of patent of invention of the InGaN series broad band solar battery containing multi-quantum pit structure, structure comprises a substrate, it is followed successively by transition zone, p-type InGaN layer, two kinds of different components InGaN material composition multi-quantum pit structure layer and N-shaped InGaN layer; The patent No. is 200810240351.4, name is called: the patent of invention of p-i-n type InGaN quantum dot solar battery structure and preparation method thereof, structure comprises: a substrate, it is followed successively by low temperature nitride sow nucleating layer, unintentionally adulterate nitrogenize sow resilient coating, N-shaped doping In _xga _1-xn layer, undoped i layer In _yga _1-yn quantum-dot structure and p-type doping In _xga _l-xn layer.The photoelectric conversion efficiency of foregoing invention patent is all improved, but quantum well or quantum dot cause the complex process of battery structure in epitaxial growth, add the manufacture difficulty of battery; The patent No. is 200710062978.0, and name is called: the patent of invention of unijunction indium gallium nitrogen solar battery structure and manufacture method, and structure comprises: a substrate, it is followed successively by a low temperature nitride and sows nucleating layer, one unintentionally adulterate nitrogenize sow resilient coating, one N-shaped doping In _xga _1-xn layer, a p-type doping In _xga _1-xn layer, patent of the present invention is without quantum dot or quantum well structure, and manufacturing process is simple, capability of resistance to radiation is strong, but photoelectric conversion efficiency need to improve.

Above-mentioned technology all describes the growth course to InGaN material, directly cannot apply as complete solar cell, and few to the collection of charge carrier, affects useful life.

Summary of the invention

The present invention provides a kind of long service life, strengthens collection to charge carrier, can directly apply for solving in known technology the technical problem that exists, and is easy to the p-i-n type unijunction InGaN solar cell prepared, capability of resistance to radiation is strong, photoelectric conversion efficiency is high.

The technical scheme that the present invention takes for the technical problem existed in solution known technology is:

A kind of p-i-n type unijunction InGaN solar cell, comprise a substrate, it is followed successively by the 10-35nm thick GaN nucleating layer of 500-650 DEG C of growth, 1-2.5 μm of thick GaN resilient coating of 950-1100 DEG C growth, the thick doping content of 200nm-250nm of 600-1100 DEG C growth be 1 × 10 ¹⁸-1 × 10 ¹⁹cm ^-3the n-GaN layer of Si doping and the thick doping content of 100-150nm of 600-1100 DEG C of growth are 1 × 10 ¹⁷-1 × 10 ¹⁸cm ^-3the p-GaN layer of Mg doping; The 500-1000 DEG C of thick unadulterated i-In of the 150-200nm grown is had between the n-GaN layer of described Si doping and the p-GaN layer of Mg doping _xga _1-xn layer, wherein 0.5≤x≤0.8, be characterized in: above the p-GaN layer of described Mg doping, evaporation has translucent current extending, and described translucent current extending is the thick ito thin film of 100-300nm, and above translucent current extending, evaporation has positive electrode; Above the n-GaN layer of described Si doping, evaporation has negative electrode.

The present invention can also take following technical scheme:

Described positive electricity very thickness be 30nm Ni and Ni on face thickness be the Au of 80nm.

Described negative electricity is followed successively by the Ti/Al/Au of thickness 20nm/20nm/200nm very from bottom to top.

The advantage that the present invention has and good effect are:

1, the present invention adopts and is widely used in the growth technique of the field maturations such as LED, laser diode and photodetection, grows unadulterated i-In by the n-GaN layer that adulterates at Si _xga _1-xn layer, improves photoelectric conversion efficiency, and relative to the solar cell of quantum dot or quantum well structure, is easy to preparation.

2, the present invention is by the translucent current extending of evaporation, strengthens the collection to charge carrier, and further increases capability of resistance to radiation, extend the useful life of battery.

3, the present invention is by the device technology such as the translucent current extending of evaporation and positive and negative electrode, achieves the direct application of complete solar cell.

Accompanying drawing explanation

Fig. 1 is p-i-n type unijunction InGaN solar cell schematic front view of the present invention;

Fig. 2 is the schematic top plan view after the present invention's first time photoetching;

Fig. 3 is the schematic top plan view after the photoetching of the present invention's second time.

In figure: 1, substrate; 2, GaN nucleating layer; 3, GaN resilient coating; 4, n-GaN layer; 5, negative electrode; 6, i-In _xga _1-xn layer; 7, p-GaN layer; 8, translucent current extending; 9, positive electrode; 10, protection zone; 11, etching region; 12, positive electrode area; 13, negative electrode area.

Embodiment

For technology contents of the present invention, Characteristic can be understood further, hereby exemplify following examples, and coordinate accompanying drawing to be described in detail as follows:

Accompanying drawings 1-Fig. 3.

First MOCVD and metal organic chemical vapor deposition technology growing GaN nucleating layer 2, GaN resilient coating 3, n-GaN layer 4, i-In successively in Sapphire Substrate 1 is adopted _xga _1-xn layer 6 and p-GaN layer 7, concrete manufacturing process is:

GaN nucleating layer, growth temperature is 500-650 DEG C, and thickness range is 10-35nm, and this layer can increase the nucleation density of substrate surface;

GaN resilient coating, growth temperature is 950-1100 DEG C, and thickness range is 1-2.5 μm, and this layer can reduce the defect concentration of epitaxial loayer, thus improves crystal mass;

The n-GaN layer of Si doping, growth temperature is 600-1100 DEG C, and doping content is 1 × 10 ¹⁸-1 × 10 ¹⁹cm ^-3, thickness range is 200nm-250nm, and this thickness range can ensure the absorption of light and the diffusion in hole simultaneously;

Unadulterated i-In _xga _1-xn layer, wherein 0.5≤x≤0.8, growth temperature is 500-1000 DEG C, and thickness range is 150-200nm, if exceed this thickness range, internal electric field can die down in this region;

The p-GaN layer of Mg doping, growth temperature is 600-1100 DEG C, and doping content is 1 × 10 ¹⁷-1 × 10 ¹⁸cm ^-3, thickness range is 100-150nm, and this thickness range can provide enough electric charges, and suitable top metal contact condition.

After above-mentioned layers of material growth, in p-GaN layer, evaporation ito film is as translucent current extending 8, then carries out first time photoetching, dry etching, second time photoetching, evaporation positive electrode 9 and negative electrode 5 successively:

Evaporation ITO: adopt traditional evaporation process evaporation ito film.For keeping the chemistry of ito thin film more unbalance than not, during evaporation, vacuum degree is 10 ^-4below Pa, through-current capacity is about the oxygen of 3.5sccm simultaneously, and the translucent current extending of final formation, its thickness range 100-300nm, is placed on the N of 450 DEG C afterwards ₂under environment, anneal 15 minutes;

First time photoetching: adopt traditional photoetching process, make protection zone 10 and etching region 11 by lithography according to Fig. 2 on translucent current extending;

Dry etching: adopt traditional dry method etch technology, removes the translucent current extending of etching region, p-GaN layer and i-In _xga _1-xn layer, etch depth is approximately 350nm;

Second time photoetching: adopt traditional photoetching process, the translucent current extending of protection zone carves the positive electrode area 12 shown in Fig. 3, the n-GaN layer 4 of etching region carves the negative electrode area 13 shown in Fig. 3;

Evaporation positive electrode: the Ni adopting traditional evaporation process first evaporation a layer thickness 30nm in positive electrode area, then the Au of evaporation a layer thickness 80nm, evaporation 20 minutes, forms the positive electrode shown in Fig. 1; Vacuum degree during evaporation is 10 ^-4below Pa, finally at the N of 500 DEG C ₂under environment, anneal 1 minute;

Evaporation negative electrode: adopt traditional evaporation process to be the Ti/Al/Au of 20nm/20nm/200nm in negative electrode area successively evaporation thickness, evaporation 20 minutes, forms the negative electrode shown in Fig. 1; Vacuum degree during evaporation will be 10 ^-4below Pa, finally at the N of 800 DEG C ₂under environment, anneal 3 minutes.

By the enforcement of above step, complete the manufacturing process of p-i-n type unijunction InGaN solar cell of the present invention.

Be more than the detailed description to the present invention one specific embodiment, this case protection range do not constituted any limitation that the technical method that all employing equivalents or equivalence are replaced and formed all drops within rights protection scope of the present invention.

Claims

1. a p-i-n type unijunction InGaN solar cell, comprise a substrate, it is followed successively by the 10-35nm thick GaN nucleating layer of 500-650 DEG C of growth, 1-2.5 μm of thick GaN resilient coating of 950-1100 DEG C growth, the thick doping content of 200nm-250nm of 600-1100 DEG C growth be 1 × 10 ¹⁸-1 × 10 ¹⁹cm ^-3the n-GaN layer of Si doping and the thick doping content of 100-150nm of 600-1100 DEG C of growth are 1 × 10 ¹⁷-1 × 10 ¹⁸cm ^-3the p-GaN layer of Mg doping; The 500-1000 DEG C of thick unadulterated i-In of the 150-200nm grown is had between the n-GaN layer of described Si doping and the p-GaN layer of Mg doping _xga _1-xn layer, wherein 0.5≤x≤0.8, is characterized in that: above the p-GaN layer of described Mg doping, evaporation has translucent current extending, and described translucent current extending is the thick ito thin film of 100-300nm, and above translucent current extending, evaporation has positive electrode; Above the n-GaN layer of described Si doping, evaporation has negative electrode.

2. p-i-n type unijunction InGaN solar cell according to claim 1, is characterized in that: described positive electricity very thickness be 30nm Ni and Ni on face thickness be the Au of 80nm.

3. p-i-n type unijunction InGaN solar cell according to claim 1, is characterized in that: described negative electricity is followed successively by the Ti/Al/Au of thickness 20nm/20nm/200nm very from bottom to top.