CN203085627U - Non-polar blue LED epitaxial wafer grown on LiGaO2 substrate - Google Patents

Abstract

The utility model discloses a non-polar blue light LED epitaxial wafer growing on a LiGaO2 substrate comprising, from bottom to top, a LiGao2 substrate, a non-polar m surface GaN buffer layer, a non-polar m surface GaN epitaxial layer, a non-polar non-doped GaN layer, a non-polar n-type doped GaN film, a non-polar InGaN/Gan quantum well layer, and a non-polar p-type doped GaN film sequentially. Compared to the prior art, the utility model is advantageous in that the growing technology is simple, the preparation costs are low; the prepared non-polar blue light LED epitaxial wafer has advantages of low defect density, good crystallization quality, and good electrical, optical properties.

Description

Non-polar blue LED epitaxial wafer grown on LiGaO2 substrate

technical field

The utility model relates to a nonpolar blue light LED epitaxial sheet, in particular to a nonpolar blue light LED epitaxial sheet grown on a _LiGaO2 substrate.

Background technique

LED is called the fourth-generation lighting source or green light source. It has the characteristics of energy saving, environmental protection, long life, and small size. It can be widely used in various fields such as general lighting, indication, display, decoration, backlight, and urban night scenes. At present, under the background of the increasingly serious problem of global warming, energy conservation and reduction of greenhouse gas emissions have become important issues faced by the whole world. A low-carbon economy based on low energy consumption, low pollution, and low emissions will become an important direction of economic development. In the field of lighting, the application of LED light-emitting products is attracting the attention of the world. As a new type of green light source product, LED must be the trend of future development. The 21st century will be an era of new lighting sources represented by LEDs.

Group III nitride semiconductor material GaN is the most ideal material for manufacturing high-efficiency LED devices. At present, the luminous efficiency of GaN-based LEDs has reached 28% and is still increasing, which is much higher than that of the commonly used incandescent lamps (about 2%) or fluorescent lamps (about 10%). Luminous efficiency. Statistics show that my country's current lighting electricity consumption is more than 410 billion kWh per year, which exceeds the annual electricity consumption of the UK. If LEDs are used to replace all incandescent lamps or partially replace fluorescent lamps, nearly half of the lighting power consumption can be saved, exceeding the annual power generation of the Three Gorges Project. Greenhouse gas emissions from lighting are also significantly reduced as a result. In addition, compared with fluorescent lamps, GaN-based LEDs do not contain toxic mercury elements, and the service life is about 100 times longer than that of such lighting tools.

If LEDs are to be widely used on a large scale, it is necessary to further improve the luminous efficiency of LED chips. Although the luminous efficiency of LED has surpassed that of fluorescent lamps and incandescent lamps, the luminous efficiency of commercial LEDs is still lower than that of sodium lamps (150lm/W), and the price per lumen/watt is relatively high. At present, the luminous efficiency of LED chips is not high enough, one of the main reasons is due to its sapphire substrate. LED technology based on sapphire substrates has two serious problems. First of all, the lattice mismatch rate between sapphire and GaN is as high as 17%. Such a high lattice mismatch makes the LED epitaxial wafer on sapphire have a high defect density, which greatly affects the luminous efficiency of the LED chip. Secondly, the sapphire substrate is very expensive, which makes the production cost of nitride LEDs very high (the sapphire substrate occupies a considerable proportion in the production cost of LEDs).

Another main reason why the luminous efficiency of LED chips is not high enough is that GaN-based LEDs widely used at present have polarity. At present, the most ideal material for manufacturing high-efficiency LED devices is GaN. GaN has a close-packed hexagonal crystal structure, and its crystal planes are divided into polar c-plane [(0001) plane], non-polar a-plane [(11-20) plane] and m-plane [(1-100) plane] . At present, GaN-based LEDs are mostly constructed based on the polar face of GaN. On the polar plane GaN, the centroids of the Ga atom assembly and the N atom assembly do not coincide, thereby forming an electric dipole, generating a spontaneous polarization field and a piezoelectric polarization field, and then causing the Quantum-confined Stark effect (Quantum-confined Stark effect). Starker Effect, QCSE), which separates electrons and holes, and reduces the radiative recombination efficiency of carriers, which ultimately affects the luminous efficiency of the LED and causes the instability of the LED luminous wavelength. The best way to solve this problem is to use non-polar GaN material to make LEDs to eliminate the influence of the quantum-bound Stark effect. Theoretical studies have shown that the use of non-polar surface GaN to manufacture LEDs will nearly double the luminous efficiency of LEDs.

It can be seen that the most fundamental way to make LEDs truly realize large-scale and wide application, improve the luminous efficiency of LED chips, and reduce their manufacturing costs is to develop non-polar GaN-based LED epitaxial chips on new substrates. Therefore, the epitaxial growth of non-polar gallium nitride LED epitaxial wafers on new substrates has always been a hot and difficult research point.

Utility model content

In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of this utility model is to provide a non-polar blue LED epitaxial wafer grown on a _LiGaO2 substrate, which has the advantages of low defect density, good crystal quality and good luminous performance , and the preparation cost is low.

The purpose of this utility model is achieved through the following technical solutions:

Nonpolar blue LED epitaxial wafer grown on _LiGaO2 substrate, including _LiGaO2 substrate, nonpolar m-plane GaN buffer layer, nonpolar m-plane GaN epitaxial layer, nonpolar nonpolar Doped u-GaN layer, non-polar n-type doped GaN film, non-polar InGaN/GaN quantum well layer, non-polar p-type doped GaN film.

The crystal orientation of the LiGaO ₂ substrate is that the (100) crystal plane is deflected to the (110) direction by 0.2-0.5°.

A non-polar blue LED epitaxial wafer grown on a LiGaO ₂ substrate, the thickness of the non-polar m-plane GaN buffer layer is 30-60 nm; the thickness of the non-polar m-plane GaN epitaxial layer is 150-250 nm; The thickness of the non-polar non-doped u-GaN layer is 300-500 nm; the thickness of the non-polar n-type doped GaN layer is 3-5 μm; the non-polar InGaN/GaN quantum well layer is 5-10 nm. A period of InGaN well layer/GaN barrier layer, wherein the thickness of the InGaN well layer is 2~3nm; the thickness of the GaN barrier layer is 10~13nm; the thickness of the nonpolar p-type doped GaN film is 350~500nm, The electron concentration of the non-polar n-type doped GaN film is 1.0×10 ¹⁷ ~5.0×10 ¹⁹ cm ^-3 , and the hole concentration of the non-polar p-type doped GaN film is 1.0×10 ¹⁶ ~2.0 ×10 ¹⁸ cm ^-3 .

The preparation method of the nonpolar blue light LED epitaxial wafer grown on the _LiGaO2 substrate comprises the following steps:

(1) Using LiGaO ₂ substrate, select the crystal orientation;

(2) Annealing the substrate: bake the substrate at 900-1000°C for 3-5 hours, then air-cool to room temperature;

(3) Surface cleaning of the substrate;

(4) Low-temperature molecular beam epitaxy is used to grow the non-polar m-plane GaN buffer layer. The process conditions are: the substrate temperature is 220-350°C, the Ga evaporation source and N plasma are introduced, and the reaction chamber pressure is 5-7× 10 ^-5 torr, the RF power for generating plasma nitrogen is 200~300W, the V/III ratio is 50~60, and the growth rate is 0.4~0.6ML/s;

(5) The non-polar m-plane GaN epitaxial layer is grown by pulsed laser deposition process. The process conditions are as follows: the substrate temperature rises to 450~550°C, pulsed laser is used to bombard the Ga target, and N ₂ is introduced at the same time, and the reaction chamber pressure is 3~5×10 ^-5 torr, laser energy 120~180mJ, laser frequency 10~30Hz;

(6) Molecular beam epitaxy is used to grow non-polar and non-doped u-GaN layers. The process conditions are: the substrate temperature is 700~800°C, the Ga evaporation source and N plasma are introduced, and the reaction chamber pressure is 5~7 ×10 ^-5 torr, the RF power for generating plasma nitrogen is 200~300W;

(7) The non-polar n-type doped GaN film is grown by pulsed laser deposition process. The process conditions are as follows: the substrate temperature is 450~550°C, the pulsed laser is used to bombard the GaSi mixed target, N plasma is introduced during the growth, and the reaction The chamber pressure is 5~7×10 ^-5 torr, the RF power is 200~300W, the laser energy is 120~180mJ, the laser frequency is 10~30Hz, and the electron carrier concentration is determined by the atomic ratio of the two elements in the GaSi mixed target To control, the doping electron concentration is 1.0×10 ¹⁷ ~5.0×10 ¹⁹ cm ^-3 ;

(8) Molecular beam epitaxy is used to grow non-polar InGaN/GaN quantum wells. The process conditions are: the substrate temperature is 500~750°C, the Ga evaporation source and N plasma are introduced, and the reaction chamber pressure is 5~7×10 ^-5 torr, the RF power for generating plasma nitrogen is 200~300W;

(9) The non-polar p-type doped GaN film is grown by pulsed laser deposition process. The process conditions are as follows: the substrate temperature is 450~550°C, and the pulsed laser is used to bombard the GaMg mixed target to grow the p-type GaN film. N plasma is injected, the pressure of the reaction chamber is 5~7×10 ^-5 torr, the radio frequency power is 200~300W, the laser energy is 120~180mJ, the laser frequency is 10~30Hz, and the carrier concentration of holes is obtained by GaMg mixed target The atomic ratio of the two elements in the material is controlled, and the doping hole concentration is 1.0×10 ¹⁶ ~2.0×10 ¹⁸ cm ^-3 .

The preparation method of the nonpolar blue LED epitaxial wafer grown on the _LiGaO2 substrate, comprising the thickness of the nonpolar m-plane GaN buffer layer is 30 ~ 60nm; the thickness of the nonpolar m-plane GaN epitaxial layer is 150~250nm; the thickness of the nonpolar non-doped u-GaN layer is 300~500nm; the thickness of the nonpolar n-type doped GaN layer is 3~5μm; the nonpolar InGaN/GaN quantum well layer InGaN well layer/GaN barrier layer of 5-10 periods, wherein the thickness of the InGaN well layer is 2-3nm; the thickness of the GaN barrier layer is 10-13nm; the thickness of the non-polar p-type doped GaN film is 350~500nm.

The preparation method of the non-polar blue light LED epitaxial wafer grown on the LiGaO ₂ substrate, the surface cleaning treatment of the substrate as described in step (3), specifically:

Put the LiGaO ₂ substrate in deionized water and ultrasonically clean it at room temperature for 5 to 10 minutes to remove the dirt particles on the surface of the LiGaO ₂ substrate, and then wash it with hydrochloric acid, acetone, and ethanol in order to remove the surface organic matter; the cleaned LiGaO ₂ substrate Blow dry with high-purity dry nitrogen; then put the LiGaO ₂ substrate into a low-temperature molecular beam epitaxy growth chamber, raise the substrate temperature to 850-900°C under ultra-high vacuum conditions, and bake for 20-30 minutes to remove LiGaO ₂ Residual impurities on the surface of the substrate.

Compared with the prior art, the utility model has the following advantages and beneficial effects:

(1) This utility model uses LiGaO ₂ as the substrate, and at the same time adopts low-temperature molecular beam epitaxy technology to grow a non-polar m-plane GaN buffer layer on the LiGaO ₂ substrate to obtain the substrate and non-polar m-plane GaN epitaxy The very low lattice mismatch between layers is conducive to the deposition of low-defect non-polar GaN thin films, which greatly improves the luminous efficiency of LEDs.

(2) The utility model adopts low-temperature molecular beam epitaxy technology to grow a layer of non-polar m-plane GaN buffer layer on the LiGaO ₂ substrate, which can ensure the stability of the LiGaO ₂ substrate at low temperature and reduce the volatilization of lithium ions. The lattice mismatch and severe interfacial reaction lay a good foundation for the next step of growing non-polar m-plane GaN epitaxial layer.

(3) The utility model adopts the combination of molecular beam epitaxy and pulsed laser deposition technology to prepare high-quality non-polar blue LED epitaxial wafers, which eliminates the quantum-bound Stark effect brought about by GaN on the polar surface, and improves the current carrying capacity. The radiative recombination efficiency of electrons can greatly improve the efficiency of nitride devices such as semiconductor lasers, light-emitting diodes and solar cells.

(4) The utility model uses LiGaO ₂ as the substrate, which is easy to obtain and cheap, and is conducive to reducing production costs.

Description of drawings

1 is a schematic cross-sectional view of a non-polar blue LED epitaxial wafer grown on a LiGaO ₂ substrate prepared in Example 1.

2 is an XRD test chart of the non-polar blue LED epitaxial wafer grown on the LiGaO ₂ substrate prepared in Example 1.

3 is a photoluminescence PL spectrum test chart of the non-polar blue LED epitaxial wafer grown on the LiGaO ₂ substrate prepared in Example 1.

4 is an electroluminescence EL spectrum test diagram of the non-polar blue LED epitaxial wafer grown on the LiGaO ₂ substrate prepared in Example 1.

Detailed ways

The utility model will be described in further detail below in conjunction with the embodiments and accompanying drawings, but the implementation of the utility model is not limited thereto.

Example 1

The preparation method of the non-polar blue light LED epitaxial wafer grown on the _LiGaO2 substrate in this embodiment comprises the following steps:

(1) Using LiGaO ₂ substrate, the crystal orientation is selected as (100) crystal plane biased to (110) direction by 0.2°;

(2) Anneal the substrate: bake the substrate at 900°C for 3 hours, then air cool to room temperature;

(3) Clean the surface of the substrate: put the LiGaO ₂ substrate in deionized water and ultrasonically clean it for 5 minutes at room temperature to remove the sticky particles on the surface of the LiGaO ₂ substrate, and then wash with hydrochloric acid, acetone, and ethanol in sequence to remove the surface organic matter; the cleaned LiGaO ₂ substrate is dried with high-purity dry nitrogen; then the LiGaO ₂ substrate is placed in a low-temperature molecular beam epitaxy growth chamber, and the substrate temperature is raised to 850°C under ultra-high vacuum conditions, and baked 20 minutes, remove LiGaO ₂ residual impurities on the substrate surface;

(4) The non-polar m-plane GaN buffer layer is grown by low-temperature molecular beam epitaxy. The process conditions are: the substrate temperature is 220°C, the Ga evaporation source and N plasma are introduced, and the reaction chamber pressure is 5×10 ^-5 torr , The radio frequency power for generating plasma nitrogen is 200W, the V/III ratio is 50, and the growth rate is 0.4ML/s;

(5) The non-polar m-plane GaN epitaxial layer was grown by pulsed laser deposition process. The process conditions were as follows: the substrate temperature was raised to 450°C, the pulsed laser was used to bombard the Ga target, and N ₂ was introduced at the same time, and the pressure of the reaction chamber was 3× 10 ^-5 torr, laser energy 120mJ, laser frequency 10Hz;

(6) Molecular beam epitaxy is used to grow non-polar and non-doped u-GaN layers. The process conditions are: the substrate temperature is 700°C, the Ga evaporation source and N plasma are introduced, and the reaction chamber pressure is 5×10 ^-5 torr, the RF power for generating plasma nitrogen is 200W;

(7) The non-polar n-type doped GaN film is grown by pulsed laser deposition process. The process conditions are as follows: the substrate temperature is 450°C, the pulsed laser is used to bombard the GaSi mixed target, N plasma is introduced during the growth, and the pressure of the reaction chamber is 5×10 ^-5 torr, RF power 200W, laser energy 120mJ, laser frequency 10Hz, doped electron concentration 1.0×10 ¹⁷ cm ^-3 ;

(8) Nonpolar InGaN/GaN quantum wells are grown by molecular beam epitaxy. The process conditions are as follows: the substrate temperature is 500°C, the Ga evaporation source and N plasma are introduced, and the reaction chamber pressure is 5×10 ^-5 torr, The RF power for generating plasma nitrogen is 200W;

(9) The non-polar p-type doped GaN film is grown by pulsed laser deposition process. The process conditions are as follows: the substrate temperature is 450°C, the pulsed laser is used to bombard the GaMg mixed target to grow the p-type GaN film, and N Plasma, the reaction chamber pressure is 5×10 ^-5 torr, the RF power is 200-300W, the laser energy is 120mJ, the laser frequency is 10Hz, and the hole carrier concentration is determined by the atomic ratio of the two elements in the GaMg mixed target control, the doping hole concentration is 1.0×10 ¹⁶ cm ^-3 .

As shown in Figure 1, the nonpolar blue LED epitaxial wafer grown on the _LiGaO2 substrate prepared in this embodiment includes a _LiGaO2 substrate 11, a nonpolar m-plane GaN buffer layer 12, Nonpolar m-plane GaN epitaxial layer 13, nonpolar non-doped u-GaN layer 14, nonpolar n-type doped GaN film 15, nonpolar InGaN/GaN quantum well layer 16, nonpolar p-type doped Doped GaN thin film 17; wherein, the thickness of the nonpolar m-plane GaN buffer layer is 30~60nm; the thickness of the nonpolar m-plane GaN epitaxial layer is 150nm; the thickness of the nonpolar non-doped u-GaN layer The thickness is 300nm; the thickness of the non-polar n-type doped GaN layer is 3 μm; the non-polar InGaN/GaN quantum well layer is 5 cycles of InGaN well layer/GaN barrier layer, wherein the thickness of the InGaN well layer is The thickness of the GaN barrier layer is 10 nm; the thickness of the non-polar p-type doped GaN film is 350 nm.

Fig. 2 is an XRD test pattern of the non-polar blue LED epitaxial wafer grown on the LiGaO ₂ substrate (100) surface prepared in this embodiment. The half-maximum width (FWHM) value of the LED epitaxial wafer × ray hysteresis curve was obtained through the test, and its half-maximum width (FWHM) value was lower than 0.1°. The satellite peaks of the blue LED epitaxial wafers were tested, and the strongest peak was GaN, and the left and right sides were the first-level satellite peaks and the second-level satellite peaks of the quantum well. The flakes have very good properties both in terms of defect density and crystalline quality.

Fig. 3 is a PL spectrum test chart of the non-polar m-plane blue LED epitaxial wafer grown on the LiGaO ₂ substrate prepared in this embodiment at room temperature. It can be seen from the figure that the PL spectrum test under the temperature of 293K shows that the luminous peak wavelength is 444nm, the half-maximum width is 26nm, and the thickness of the LED is 5.95um. It shows that the non-polar GaN thin film prepared by the utility model has very good performance in optical properties.

Fig. 4 is an EL spectrum test chart of the non-polar m-plane blue LED epitaxial wafer grown on the LiGaO ₂ substrate prepared in this embodiment at room temperature. It can be seen from the figure that the EL spectrum test at the temperature of 293K results in a luminous peak wavelength of 450nm, a half-maximum width of 22nm, an output power of 1.5mw20mA, and an illuminance of 0.05lm. It shows that the non-polar GaN film prepared by the utility model has very good performance in electrical properties.

Example 2

The preparation method of the non-polar blue light LED epitaxial wafer grown on the _LiGaO2 substrate in this embodiment comprises the following steps:

(1) Using LiGaO ₂ substrate, the crystal orientation is selected as (100) crystal plane biased to (110) direction by 0.5°;

(2) Annealing the substrate: bake the substrate at 1000°C for 5 hours, then air cool to room temperature;

(3) Surface cleaning of the substrate: Put the LiGaO ₂ substrate into deionized water and ultrasonically clean it at room temperature for 10 minutes to remove the sticky dirt particles on the surface of the LiGaO ₂ substrate, and then wash with hydrochloric acid, acetone, and ethanol in sequence to remove the surface Organic matter; the cleaned LiGaO ₂ substrate is dried with high-purity dry nitrogen; then the LiGaO ₂ substrate is placed in a low-temperature molecular beam epitaxy growth chamber, and the substrate temperature is raised to 900°C under ultra-high vacuum conditions, and baked 30 minutes, remove LiGaO ₂ residual impurities on the substrate surface;

(4) The non-polar m-plane GaN buffer layer is grown by low-temperature molecular beam epitaxy. The process conditions are: the substrate temperature is 350°C, the Ga evaporation source and N plasma are introduced, and the reaction chamber pressure is 7×10 ^-5 torr , The radio frequency power for generating plasma nitrogen is 300W, the V/III ratio is 60, and the growth rate is 0.6ML/s;

(5) The non-polar m-plane GaN epitaxial layer was grown by pulsed laser deposition process. The process conditions were as follows: the substrate temperature was raised to 550°C, the pulsed laser was used to bombard the Ga target, and N ₂ was introduced at the same time, and the pressure of the reaction chamber was 5× 10 ^-5 torr, laser energy 180mJ, laser frequency 30Hz;

(6) The non-polar and non-doped u-GaN layer is grown by molecular beam epitaxy. The process conditions are: the substrate temperature is 800°C, the Ga evaporation source and N plasma are introduced, and the reaction chamber pressure is 7×10 ^-5 torr, the RF power for generating plasma nitrogen is 300W;

(7) The non-polar n-type doped GaN film is grown by pulsed laser deposition process. The process conditions are as follows: the substrate temperature is 550°C, the pulsed laser is used to bombard the GaSi mixed target, N plasma is introduced during the growth, and the pressure of the reaction chamber is 7×10 ^-5 torr, RF power 300W, laser energy 180mJ, laser frequency 30Hz, doped electron concentration 5.0×10 ¹⁹ cm ^-3 ;

(8) Non-polar InGaN/GaN quantum wells are grown by molecular beam epitaxy. The process conditions are as follows: substrate temperature is 750°C, Ga evaporation source and N plasma are introduced, and reaction chamber pressure is 7×10 ^-5 torr. The RF power for generating plasma nitrogen is 300W;

(9) The non-polar p-type doped GaN film is grown by pulsed laser deposition process. The process conditions are as follows: the substrate temperature is 550°C, the pulsed laser is used to bombard the GaMg mixed target to grow the p-type GaN film, and the N Plasma, the reaction chamber pressure is 7×10 ^-5 torr, the radio frequency power is 300W, the laser energy is 180mJ, the laser frequency is 30Hz, the hole carrier concentration is controlled by the atomic ratio of the two elements in the GaMg mixed target, The doping hole concentration is 2.0×10 ¹⁸ cm ^-3 .

The nonpolar blue LED epitaxial wafer grown on the LiGaO ₂ substrate prepared in this example includes a LiGaO ₂ substrate, a nonpolar m-plane GaN buffer layer, and a nonpolar m-plane GaN epitaxial layer arranged in sequence from bottom to top. , non-polar non-doped u-GaN layer, non-polar n-type doped GaN film, non-polar InGaN/GaN quantum well layer, non-polar p-type doped GaN film; wherein, the non-polar m The thickness of the GaN buffer layer is 60nm; the thickness of the non-polar m-plane GaN epitaxial layer is 250nm; the thickness of the non-polar non-doped u-GaN layer is 500nm; the non-polar n-type doped GaN layer The thickness of the InGaN/GaN quantum well layer is 10 cycles of InGaN well layer/GaN barrier layer, wherein the thickness of the InGaN well layer is 3nm; the thickness of the GaN barrier layer is 13nm; the nonpolar The thickness of the p-type doped GaN thin film is 500nm.

The above-mentioned embodiment is a preferred implementation mode of the present utility model, but the implementation mode of the present utility model is not limited by the described embodiment, and any other changes, modifications, modifications, Substitution, combination, and simplification should all be equivalent replacement methods, and are all included in the protection scope of the present utility model.

Claims (3)

1. A nonpolar blue LED epitaxial wafer grown on a _LiGaO2 substrate, characterized in that it comprises a _LiGaO2 substrate, a nonpolar m-plane GaN buffer layer, and a nonpolar m-plane GaN epitaxial wafer arranged in sequence from bottom to top. Layer, non-polar non-doped u-GaN layer, non-polar n-type doped GaN film, non-polar InGaN/GaN quantum well layer, non-polar p-type doped GaN film. 2. The non-polar blue LED epitaxial wafer grown on _LiGaO2 substrate according to claim 1, characterized in that, the crystal orientation of said _LiGaO2 substrate is (100) crystal plane biased to (110) direction 0.2 ~0.5°. 3. the nonpolar blue light LED epitaxial wafer grown on _LiGaO2 substrate according to claim 1, is characterized in that, the thickness of described nonpolar m-plane GaN buffer layer is 30～60nm; The thickness of the polar m-plane GaN epitaxial layer is 150-250 nm; the thickness of the non-polar non-doped GaN layer is 300-500 nm; the thickness of the non-polar n-type doped GaN layer is 3-5 μm; the non-polar The permanent InGaN/GaN quantum well layer is an InGaN well layer/GaN barrier layer with 5~10 cycles, wherein the thickness of the InGaN well layer is 2~3nm; the thickness of the GaN barrier layer is 10~13nm; the nonpolar p-type The thickness of the doped GaN film is 350-500 nm, the electron concentration of the non-polar n-type doped GaN film is 1.0×10 ¹⁷ ~5.0×10 ¹⁹ cm ^-3 ; the non-polar p-type doped GaN film The hole concentration is 1.0×10 ¹⁶ ~2.0×10 ¹⁸ cm ^-3 .

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