CN117353154A

CN117353154A - GaN-based photoelectric device

Info

Publication number: CN117353154A
Application number: CN202311277813.0A
Authority: CN
Inventors: 张帆; 王荣新; 杨辉; 刘建平; 张珽
Original assignee: Suzhou Institute of Nano Tech and Nano Bionics of CAS
Current assignee: Suzhou Institute of Nano Tech and Nano Bionics of CAS
Priority date: 2023-09-28
Filing date: 2023-09-28
Publication date: 2024-01-05

Abstract

The invention discloses a GaN-based photoelectric device. The GaN-based photoelectric device comprises a first light limiting layer, a first waveguide layer, an active layer, a second waveguide layer, an electronic blocking layer, a second light limiting layer, an ohmic contact layer and a doped ZnO layer which are sequentially stacked along a selected direction, wherein the doped ZnO layer is stacked along the selected direction and arranged on the ohmic contact layer, the doped ZnO layer and the ohmic contact layer form ohmic contact, and the doped ZnO layer also has an optical limiting effect. The invention reduces the working voltage of the photoelectric device, increases the output efficiency and improves the device performance of the photoelectric device.

Description

GaN-based photoelectric device

Technical Field

The invention particularly relates to a GaN-based photoelectric device, and belongs to the technical field of semiconductor photoelectric devices.

Background

GaN-based semiconductors are suitable materials for ultraviolet, blue and green Light Emitting Diodes (LEDs) and Lasers (LDs). In recent years, research on GaN-based materials has been greatly advanced, so that the performance of gallium nitride (GaN) -based photoelectric devices, such as laser diodes, light emitting diodes, power devices, purple photodetectors, and the like, is greatly improved. In particular, gaN-based lasers have been widely used in the fields of biochemical analysis, full-color display, laser processing, high-density storage, laser pumping, laser lithography, and the like in recent years.

The conventional semiconductor laser comprises a substrate, a lower light limiting layer, a lower waveguide layer, a quantum well active region, a waveguide layer, an upper light limiting layer, a metal contact layer and other structures. The light-limiting layer limits light to the quantum well active region by adopting aluminum gallium nitride (AlGaN) or aluminum gallium nitride/gallium nitride superlattice, and the contact metal forms ohmic contact with p-type GaN by adopting metal combinations such as palladium/platinum/gold (Pd/Pt/Au) or titanium/gold (Ti/Au).

In order to meet the requirements of wide-ranging applications, gaN lasers require higher output power, lower resistance and better thermal stability. There are many factors that affect the performance of a laser device, such as material quality, ohmic contacts, cleavage, faceting coatings, and the like. Among these factors, the optical loss of the p-type AlGaN confinement layer and the p-type ohmic contact can be said to be very important issues. GaN blue-green lasers typically employ p-type aluminum gallium nitride or aluminum gallium nitride/gallium nitride superlattices as the light-up confinement layer. However, there are several problems: (1) Tensile stress can be generated in the growth process of the light limiting layer on the P-type AlGaN or the P-type AlGaN/GaN superlattice, so that the epitaxial wafer is cracked. This property limits the composition and thickness of the aluminum gallium nitride layer growth, limiting the structural design of the laser. (2) The growth temperature of the light confinement layer on the p-type AlGaN or p-type AlGaN/GaN superlattice is typically over 900 ℃ and higher than the growth temperature of the quantum well active region, which can cause quantum well degradation and affect the performance of the laser. (3) The light limiting layer on the p-type AlGaN or the p-type AlGaN/GaN superlattice has high resistivity, and is a main source of series resistance of the GaN-based laser, so that the working voltage of the laser is high. (4) The p-type AlGaN layer has low hole concentration and larger square resistance, so that the p-side hole injection area is small, the current density per unit area is large, the device can generate heat seriously under the injection of large current, the service life and the reliability of the device are not facilitated, and high output power cannot be obtained. It is therefore necessary to solve these problems of the GaN-based LD and to find a method capable of limiting the optical field, obtaining stable oscillation, and simultaneously reducing the resistance and the stable p-type GaN ohmic contact to improve the luminous efficiency of the blue-green LD.

Indium Tin Oxide (ITO) doped in Transparent Conductive Oxide (TCO) is commonly used in the existing research to replace AlGaN layers or AlGaN/GaN superlattice layers, but ITO has limitations and disadvantages: the work function of the ITO film surface is between 4.6 and 4.9eV, the work function of the ITO film serving as an anode electrode material in a photoelectric device is relatively low, the work function of the ITO film serving as a cathode electrode material is relatively high, carrier energy level difference exists between the ITO film and a functional layer, potential barrier is generated, carrier injection efficiency is low, and the performance of the device is influenced; in the OLED, in the ITO electrode diffuses In the organic functional layer, and the service life of the device is also influenced; in the application of the ITO film in the solar cell, the surface roughness and the surface resistance performance are poor, and further improvement and improvement are still needed; the indium element In the ITO film has low earth storage and high purification difficulty, so the price is increased continuously along with the requirement and use of a large amount of markets at present, and meanwhile, in becomes a scarce material and is In the condition of exhaustion.

At present, a folding mobile phone screen becomes a hot spot, and has high requirements on a flexible and pliable TCO film, so that the ITO film is not resistant to bending and has obvious defects. The ITO film with high performance is prepared, the requirements on the preparation conditions are very high, the ITO film is greatly dependent on the target, the high-quality target has very high requirements on raw materials and the preparation process of the sputtering target, and the service life and the compactness of the target are very key factors.

Disclosure of Invention

The main object of the present invention is to provide a GaN-based optoelectronic device, which overcomes the drawbacks of the prior art.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention comprises the following steps:

the invention provides a GaN-based photoelectric device, which comprises a first light limiting layer, a first waveguide layer, an active layer, a second waveguide layer, an electron blocking layer, a second light limiting layer and an ohmic contact layer which are sequentially stacked along a selected direction, and further comprises:

and the doped ZnO layer is arranged on the ohmic contact layer in a lamination manner along the selected direction, forms ohmic contact with the ohmic contact layer, and has an optical limiting effect.

The optical field limiting effect of the doped ZnO layer and the AlGaN layer which are used as the optical limiting layer in a synergic manner is stronger than that of the doped ZnO layer and the AlGaN layer which are used as the optical limiting layer independently, the optical loss is lower, and the optical field is better limited in a quantum well.

Further, the doped elements contained In the doped ZnO layer comprise at least one of Al element, ga element, in element, mg element, mn element and B element, and the mass percentage ratio of the doped elements to Zn element In the doped ZnO layer is (2-10wt%) to (98-90wt%).

Further, the present inventors have found that too much proportion of Ga and other doping elements may cause a decrease in transmittance of the thin film (i.e., doped ZnO layer), and at the same time, may cause an increase in absorption coefficient of the thin film, resulting in an increase in optical loss of the optoelectronic device (LD), while too low atomic proportion of Ga and other doping elements may cause an increase in resistivity of the thin film, resulting in an increase in series resistance of the optoelectronic device, so that a suitable Zn is selected: the proportion of doping elements such as Ga is critical as the LD-limiting layer. The inventor researches show that the doping amount of elements such as Ga affects the carrier concentration and mobility of the film, and further affects the resistivity of the film, the doping amount of elements such as Ga is increased, the resistivity is reduced first and then increased, and the carrier concentration is high, so that good ohmic contact is formed. Due to the scattering effect of elements such as Ga, the transmittance and absorption coefficient of the film can be changed, the absorption coefficient of the film is affected by the doping amount of the elements such as Ga, and the proper doping amount of the elements such as Ga is beneficial to the improvement of the power of a laser.

Further, the mass percentage of the doping element in the doped ZnO layer is graded or abrupt along the selected direction.

Further, the mass percentage of the doping element in the doped ZnO layer is 2-8wt%.

Further, the doped ZnO layer comprises at least two sub-layers stacked along the selected direction, and at least one of the types and the mass percentages of the doping elements in the at least two sub-layers are different.

Further, the doped ZnO layer comprises a first doped ZnO layer and a second doped ZnO layer which are sequentially stacked on the ohmic contact layer along the selected direction, or three or more doped ZnO layers, the doped elements contained in each interlayer doped ZnO layer are the same or different, and the mass percentages of the doped elements contained in each interlayer doped ZnO layer are different.

Further, the mass percent of the doping element contained in the first doped ZnO layer is larger than the mass percent of the doping element contained in the second doped ZnO layer.

Further, the mass percentage of the doping element contained in the first doped ZnO layer is 8wt%, and the mass percentage of the doping element contained in the second doped ZnO layer is 2wt%.

Further, the mass percentage of the doping element in the doped ZnO layer is gradually decreased from 8wt% to 2wt% along the direction away from the ohmic contact layer.

Further, the gradient of the mass percent of the doping element in the doped ZnO layer is 8-2 wt%.

Further, the doped element contained in the doped ZnO layer is Al element, and the mass percentage ratio of Zn element to Al element in the doped ZnO layer is (98-92 wt%);

or the doped element contained in the doped ZnO layer is Ga element, and the mass percentage ratio of Zn element to Ga element in the doped ZnO layer is (92-98 wt%);

or the doped element contained In the doped ZnO layer is In element, and the mass percentage of Zn element and In element In the doped ZnO layer is (90-98wt%):10-2wt%;

or the doped element contained In the doped ZnO layer is Mg element, and the mass percentage of Zn element and In element In the doped ZnO layer is (90-98 wt%);

or the doped ZnO layer contains Ga element and In element, and the mass percentage of Zn element, ga element and In the doped ZnO layer is (90-98 wt%): (10-1 wt%).

The doped ZnO layer in the present invention (GZO for example) is on top of the optical confinement layer where the ohmic contact layer (p-GaN (around 20 nm) +p-InGaN (around 3-10 nm)) is grown.

By way of example, doped layer GZO may be divided into 2 sub-layers of different elemental doping levels, the first layer using GZO of a higher Ga doping concentration (e.g., ga:5 wt%) to a thickness of approximately 100nm, and the second layer using GZO of a lower Ga doping concentration (e.g., ga:2 wt%) to a thickness of approximately 100nm. The first layer uses a high doping concentration for better ohmic contact formation and the second layer uses a low doping concentration for better optical properties. During manufacturing, a magnetron sputtering or electron beam evaporation method can be adopted to deposit the film, and two targets with different doping concentrations are used for respectively depositing the film.

The Ga element in doped layer GZO may be graded, and the concentration of the Ga element (i.e., mass percent, the same applies below) may be gradually graded from 8wt% to 2wt%. Specifically, a magnetron sputtering or electron beam evaporation method can be adopted to deposit a film, two targets with different doping concentrations (for example, ga:8wt% and Ga:2 wt%) are used for codeposition, two targets are sputtered simultaneously, and the effect of gradient change of the doping concentration is achieved by adjusting the sputtering power of the two targets.

Other doping elements can be deposited in the same manner with reference to the above scheme.

In other specific embodiments, more than two groups of conductive oxide layers may be combined as a doped ZnO layer, i.e., the doped ZnO layer may include multiple sub-layers of different elemental doping species, e.g., a first layer of 50nm ITO (95 wt% in ₂ O ₃ And 5wt% SnO ₂ Or 90wt% in ₂ O ₃ And 10wt% SnO ₂ ) First, theThe two layers are GZO or AZO (other doped ZnO layers, etc.) with thickness of 100-300 nm, or the first layer is ITO (95 wt% in) with thickness of 50nm ₂ O ₃ And 5wt% SnO ₂ Or 90wt% in ₂ O ₃ And 10wt% SnO ₂ ) The second layer is GZO with the thickness of 50nm, and the third layer is AZO (other doped ZnO layers and the like) with the thickness of 100-300 nm.

In other specific embodiments, two doped ZnO layer combinations may be used as the doped ZnO layer, specifically, the first layer is a GZO (Zn: 95wt% and Ga:5 wt%) layer with a thickness of 50nm, and the second layer is a doped ZnO layer (such as AZO) with a thickness of 150-300 nm, and the doping concentration is 2wt% -5 wt%.

Further, the thickness ratio of the second light limiting layer to the doped ZnO layer is (2-5) to (1-3).

Further, the thickness of the second light limiting layer is 200-400 nm.

Further, the thickness of the doped ZnO layer is 100-300 nm.

Further, the electron blocking layer, the second light limiting layer and the ohmic contact layer are of a first conductivity type, the doped ZnO layer and the first light limiting layer are of a second conductivity type, the first conductivity type is of a P type, and the second conductivity type is of an N type.

Further, the first optical confinement layer, the first waveguide layer, the active layer, the second waveguide layer, the electron blocking layer and the ohmic contact layer are all made of GaN-based semiconductor materials.

Further, the second light confinement layer comprises p-AlxGa _1-x N layer or p-Al _x Ga _1-x N/GaN superlattice.

In a more specific embodiment, the GaN-based optoelectronic device comprises n-Al stacked in a selected direction _x Ga _1-x N-optical confinement layer, N-InGaN waveguide layer, in _x Ga _1-x N/GaN quantum well active layer, undoped u-In _x Ga _1-x N waveguide layer, p-Al _x Ga _1-x N electron blocking layer, p-Al _x Ga _1-x N/GaN superlattice lightA confinement layer, a p-GaN ohmic contact layer and a doped ZnO layer.

Further, the first light confining layer is disposed on a buffer layer disposed on the substrate.

Further, the first light confinement layer may be n-Al _x Ga _1-x N-limiting layer, N-Al _x Ga _1-x The thickness of the N limiting layer is 800 nm-1500 nm, the content of Al component is 5% -10%, and the electron concentration is 10 ¹⁷ cm ^-3 To 10 ²⁰ cm ^-3 Between them.

Further, the first waveguide layer may be n-In _x Ga _1-x N waveguide layer, N-In _x Ga _1-x The thickness of the N waveguide layer is 30 nm-150 nm, the content of in component is 3% -6%, and the electron concentration is 10 ¹⁷ cm ^-3 To 10 ²⁰ cm ^-3 Between them.

Further, the active layer may include 1 to 6 periods of undoped In _x Ga _1-x N/GaN quantum well, in _x Ga _1-x The thickness of the N quantum well is 1 nm-6 nm, the content of in component is 10% -35%, and the thickness of the GaN quantum barrier is 2 nm-20 nm.

Further, the second waveguide layer may be undoped u-In _x Ga1- _x N waveguide layer, undoped u-In _x Ga1- _x The thickness of the N waveguide layer is 30 nm-150 nm, and the content of in component is 2% -6%.

Further, the electron blocking layer may be p-Al _x Ga _1-x N electron blocking layer, p-Al _x Ga _1-x The thickness of the N electron blocking layer is 10 nm-40 nm, the component content of Al is about 10% -30%, and the hole concentration is 10% ¹⁷ cm ^-3 To 10 ²⁰ cm ^-3 Between them.

Further, the second light confinement layer comprises p-Al in a stacked arrangement _x Ga _1-x N/GaN superlattice layer or p-Al _x Ga _1-x N light confinement layer, p-Al _x Ga _1-x The N/GaN superlattice layer comprises 10-500 cycles, and has a hole concentration of 10 ¹⁷ cm ^-3 To 10 ²⁰ cm ^-3 The content of Al is 10-30%.

Further, the ohmic contact layer 9 adopts heavily doped GaN with a thickness of 10 nm-30 nm: mg layer with Mg doping concentration of 10 ¹⁹ cm ^-3 To 10 ²¹ cm ^-3 Between them.

In some more typical embodiments, the GaN-based optoelectronic device includes n-Al stacked in a selected direction _x Ga _1-x N-optical confinement layer, N-InGaN waveguide layer, in _x Ga _1-x N/GaN quantum well active layer, undoped u-In _x Ga _1-x N waveguide layer, p-Al _x Ga _1-x N electron blocking layer, p-Al _x Ga _1-x An N/GaN superlattice light limiting layer and a p-GaN ohmic contact layer.

Further, the substrate and the buffer layer are both made of GaN-based semiconductor material, further, the substrate may be an n-GaN substrate, the buffer layer may be an n-GaN buffer layer, the thickness of the n-GaN buffer layer is 0 nm-3000 nm, and the electron concentration is 10 ¹⁷ cm ^-3 To 10 ²⁰ cm ^-3 Between them.

Further, the substrate may be made of sapphire (Al ₂ O ₃ ) Silicon carbide (SiC), diamond (diamond), or silicon (Si), quartz, PET, PC, etc.

Further, the GaN-based photoelectric device comprises an LED, a solar cell, a detector, a display screen and the like.

Compared with the prior art, the invention has the advantages that:

the invention reduces the thickness of the traditional p-type AlGaN or AlGaN/GaN superlattice light limiting layer, and adopts doped ZnO transparent conductive oxide to replace part of the light limiting layer and the electrode layer, thereby reducing the working voltage of the photoelectric device, increasing the output efficiency and improving the device performance of the photoelectric device.

According to the invention, through optimization of technological parameters of film deposition, the carrier concentration and mobility of the film are improved, low resistivity is obtained, the transmittance of the film is improved, the absorption coefficient is reduced, and the performance of a photoelectric device is improved.

Drawings

Fig. 1 is a schematic diagram of a GaN-based laser according to an exemplary embodiment of the present invention.

Detailed Description

In view of the shortcomings in the prior art, the inventor of the present invention has long studied and practiced in a large number of ways to propose the technical scheme of the present invention. The technical scheme, implementation process and principle thereof will be further explained with reference to the drawings and specific embodiments, and unless otherwise indicated, the semiconductor film forming process and the like adopted in the embodiments of the present invention are known to those skilled in the art.

The development of high-efficiency InGaN Laser Diodes (LDs) is considered to be one of the most important subjects in the fields of laser display, laser communication, and the like. Transparent conductive oxides TCO, such as indium tin oxide ITO, have high transparency in the visible region, low refractive index and absorption coefficient, and small lattice mismatch with GaN, enabling it to act as a light confinement layer in LD. Although ITO has been widely used as an optical confinement layer for LD, which has the effects of confining the optical field and reducing the optical loss, it is very important to find a substitute due to the scarcity of indium on earth and the rising price.

ZnO-based TCO (transparent conductive oxide) is a wide-bandgap material, and is a non-toxic material for human consumption. It has similar electrical and optical transmission properties to ITO, for example, a film having low resistivity and high transmittance in the visible region can be obtained using gallium-doped ZnO, and a film having high resistivity in GaN or Ga ₂ O ₃ The following advantages are provided for use in the base material and device: 1) Covalent bond length of Ga-OCovalent bond length with Zn-O->Also, very close, the introduction of Ga into the crystalline structure of ZnO produces minimal lattice distortion, and tends to be more stable,the substrate material GaN is the same as Ga in the doped GZO, and when the TCO/GaN heterostructure is prepared, the GZO film is used for reducing defects introduced by lattice mismatch between the TCO and the GaN-based material. 2) Ga in GaN is easy to diffuse outwards under the action of temperature, and entering ZnO is helpful for improving the conductive characteristic and further reducing the series resistance. 3) Compared with the ITO material, the refractive index of doped ZnO is lower, which is beneficial to reducing the optical loss. The ITO is used alone, so that on one hand, the cost is relatively high, on the other hand, the lattice mismatch of the ITO and GaN is relatively large, defects are easy to generate, and the refractive index and the absorption coefficient of the ITO are larger than those of doped ZnO, so that the optical loss is increased, the performance of a device is not facilitated, and the service life is prolonged.

After the photoelectric device epitaxial wafer is grown, znO is deposited on the ohmic contact layer: the Ga transparent conductive oxide film serves as a doped ZnO layer that serves as both part of the ohmic contact layer and part of the second light confining layer. In depositing ZnO Ga, the growth apparatus may be connected to the deposition apparatus through an ultra-high vacuum pipe, the sample may be introduced into the deposition apparatus to deposit GZO, or a plasma apparatus (e.g., N ₂ Plasma) to treat the sample surface, to deposit GZO in the deposition apparatus, or to treat the surface using wet cleaning (including organic cleaning and inorganic cleaning) methods, to deposit GZO in the deposition apparatus. After the deposited film is finished, the sample is annealed, and proper atmosphere, temperature and time are selected.

Specifically, znO: ga during deposition ₂ O ₃ =95:5 (mass percent ratio), if the Ga atom ratio is too large, it results in a decrease in transmittance of the thin film and an increase in absorption coefficient of the thin film, resulting in an increase in optical loss of LD. Too low a proportion of Ga atoms leads to an increase in sheet resistivity and hence in series resistance of the optoelectronic device, and thus proper Zn is selected: the proportion of Ga is critical as an LD-limiting layer. The oxygen in the environment has the same effect in the process preparation, the content and the proportion of the oxygen not only change the optical transmission and refraction parameters and adjust the optical performance, but also influence the electrical characteristics of the film, such as the increase of the resistivity caused by the excessively high oxygen, the increase of the use power of the device and the inductorThe risk of reduced part life increases.

Specifically, in ₂ O ₃ Has high transmittance (visible light region transmittance > 80%) and carrier concentration of 10 ²¹ cm ^-3 Magnitude, hall mobility of 10-100cm ² Vs, lower resistivity 10 ^-4 On the order of Ω·cm, a band gap of about 3.5-4.3eV, a work function of about 4.6-4.9eV, a forbidden band width of 3.4eV at room temperature of ZnO, an average visible light transmittance of about 90%, and a resistivity of 10 ^-4 Omega cm, hall mobility of about 40cm ² Vs. The ZnO-Ga film is easier to form ohmic contact with an InGaN contact layer of the LD, so that defects caused by lattice mismatch between the TCO and the GaN-based material are reduced, compared with an ITO material, the refractive index of doped ZnO is lower, the light loss is reduced, and the threshold voltage is reduced.

The doped ZnO layer can also be obtained by adopting a magnetron sputtering method to sputter and coat, and the specific parameters of the magnetron sputtering method to sputter and coat are as follows: background vacuum is generally 10 ^-8 torr, the ultra-high vacuum environment can ensure the purity of the film in the sputtering process and can not be doped with H ₂ O and O ₂ And the like. The sputtering pressure is selected to be proper, the sputtering rate is reduced due to the fact that the pressure is too low, and the film grains are oversized due to the fact that the pressure is too high. The sputtering mode uses an optimized RF mode and DC mode, the RF mode has less sputter damage to the substrate, but the growth rate is slower, while the DC mode has more sputter damage to the substrate, but the growth rate is faster. The sputtering power needs to be selected to be proper, and too high power can lead to larger sputtering damage and too low power and low efficiency. The substrate temperature is generally selected to be suitable to increase the migration of sputtered particles, which can slow down the deposition rate and can also cause oxidation of the sample surface. The deposition thickness is typically chosen to be a suitable thickness (e.g., around 200 nm), which is too thin and too thick to form a good confinement for the optical field. After depositing GZO film on the LD surface, selecting proper annealing temperature, atmosphere and time (for example, annealing temperature is 300 ℃ and annealing time is 5 min), wherein too low temperature can not be Zn diffusion into InGaN, increasing carrier concentration, and too high temperature can lead to Ga ₂ O ₃ And ZnGaO oxideResulting in the formation of an additional barrier at the interface that is detrimental to the formation of ohmic contacts.

The resistivity, the reflectivity and the transmissivity of the TCO film can be changed by adjusting the growth parameters, the doping Ga proportion and the oxygen amount ratio can be adjusted, and the resistivity (comprising the carrier concentration and the mobility) as well as the refractive index and the absorption coefficient of the film can be adjusted. Changing the substrate temperature can change the size of the thin film grains, carrier concentration and mobility, and the performance of the electrical contacts.

Example 1

Referring to FIG. 1, a GaN-based optoelectronic device includes an n-GaN substrate 10, an n-GaN buffer layer, and n-Al stacked in order along a selected direction _x Ga _1-x N-optical confinement layer 20, N-InGaN waveguide layer 30, in _x Ga _1-x N/GaN quantum well active layer 40, undoped u-In _x Ga _1-x N waveguide layer 50, p-Al _x Ga _1-x N electron blocking layer 60, p-Al _x Ga _1-x An N-light confining layer 70 and a p-GaN/InGaN ohmic contact layer 80 and a doped ZnO layer 90.

In this embodiment, the n-GaN buffer layer has a thickness of 1000nm and an electron concentration of 10 ¹⁸ cm ^-3 ，n-Al _x Ga _1-x The N-limiting layer 20 had a thickness of 800nm, an Al content of 5% and an electron concentration of 10 ²⁹ cm ^-3 ，n-In _x Ga _1-x The N waveguide layer 30 had a thickness of 50nm, an in content of 4% and an electron concentration of 10 ¹⁸ cm ^-3 The active layer 40 may include 5 periods of undoped In _x Ga _1-x N/GaN quantum well, in _x Ga _1-x The thickness of the N quantum well is 4nm, the content of In component is 25%, the thickness of the GaN quantum barrier is 2nm, and undoped u-In _x Ga1- _x The N waveguide layer 50 had a thickness of 40nm, an in content of 2%, and p-Al _x Ga _1-x The N electron blocking layer 60 has a thickness of 10nm, a composition content of Al of about 10%, and a hole concentration of 10 ¹⁷ cm ^-3 ，p-Al _x Ga _1-x The thickness of the N light confinement layer 70 is 200nm, the thickness of the p-GaN layer in the p-GaN/InGaN ohmic contact layer 80 is 10nm to 30nm, and the Mg doping concentration is 10 ²⁰ cm ^-3 The thickness of the p-InGaN contact layer is 3-10nm, and the doping concentration of Mg is 10 ²⁰ cm ^-3 。

In this embodiment, the thickness of the doped ZnO layer is 100nm, the doping element of the doped ZnO layer is Ga, and the mass percentage of Ga is 5wt%.

Example 2

Referring to fig. 1, a GaN-based photoelectric device in embodiment 2 has substantially the same structure as that in embodiment 1, except that: in this embodiment, the doped ZnO layer has a thickness of 250nm.

Example 3

Referring to fig. 1, a GaN-based photoelectric device in embodiment 3 has substantially the same structure as that in embodiment 1, except that: in this embodiment, the doped ZnO layer has a thickness of 300nm.

Example 4

Referring to fig. 1, a GaN-based photoelectric device in embodiment 4 has substantially the same structure as that of embodiment 1, except that:

in this embodiment, the doping element in the doped ZnO layer is Al, and the mass percentage of Al element is 5wt%.

Example 5

Referring to fig. 1, a GaN-based photoelectric device in embodiment 5 has substantially the same structure as that of embodiment 1, except that:

in this embodiment, the doping element of the doped ZnO layer is Al, and the mass percentage of Al element is 2wt%.

Example 6

Referring to fig. 1, a GaN-based photoelectric device in embodiment 6 has substantially the same structure as that of embodiment 1, except that:

in this embodiment, the doping elements of the doped ZnO layer are Ga and Al, the mass percentage of Ga element is 3wt%, and the mass percentage of Al element is 2wt%.

Example 7

Referring to fig. 1, a GaN-based photoelectric device in embodiment 7 has substantially the same structure as that of embodiment 1, except that:

in this embodiment, the doping element of the doped ZnO layer is Al, and the mass percentage of Al element is reduced from 5wt% to 2wt% in the direction away from the ohmic contact layer.

Example 8

Referring to fig. 1, a GaN-based photoelectric device in embodiment 8 has substantially the same structure as that of embodiment 1, except that:

in this embodiment, the doped ZnO layer includes a first doped ZnO layer and a second doped ZnO layer sequentially stacked on the ohmic contact layer, the thickness of the first doped ZnO layer is 50nm, the doped element in the first doped ZnO layer is Al, the mass percentage of the Al element is 5wt%, the thickness of the second doped ZnO layer is 50nm, the doped element in the second doped ZnO layer is Al, and the mass percentage of the Al element is 2wt%.

Comparative example 1

Referring to fig. 1, a GaN-based photovoltaic device of comparative example 1 has substantially the same structure as that of example 1, except that:

in this comparative example, the doping element of the doped ZnO layer was Ga, and the mass percentage of Ga element was 10wt%.

Comparative example 2

Referring to fig. l, a GaN-based photovoltaic device of comparative example 2 has substantially the same structure as that of example 1, except that:

in this comparative example, the doped ZnO layer contained Ga as the doping element, and the mass percentage of Ga element was 1wt%.

Comparative example 3

Referring to fig. 1, a GaN-based photovoltaic device of comparative example 5 has substantially the same structure as that of example 1, except that: in this comparative example, ITO was substituted for the doped ZnO layer.

The invention adopts ZnO-based doped ZnO as TCO film to replace part of AlGaN layer or AlGaN/GaN superlattice layer, and forms light limiting layer together with AlGaN layer or AlGaN/GaN superlattice, wherein the doped ZnO can be ZnO: al (AZO), znO: mn (MZO), znO: F (FZO), znO: B (BZO), znO: ga (GZO), znO: in (IZO), znO: in/Ga (IGZO), znO: al/Ga (AGZO), znO: ga/Mn (MGZO) and the like.

Since ZnO and GaN are both wurtzite crystal structures with the same structureThe structure only has small lattice mismatch of about 1.8%, so the lattice mismatch between the doped ZnO and the GaN-based AlGaN layer or the AlGaN/GaN superlattice layer is small, and the stability and the reliability of the GaN-based photoelectric device formed by the doped ZnO and the GaN-based AlGaN layer or the AlGaN/GaN superlattice layer are higher. ZnO has relatively high transparency (usually more than 90% in the visible light range), can effectively reduce optical loss, can adjust the optical parameters and electrical characteristics thereof by adjusting the proportion of doping elements, and has resistivity (usually about 2×10 ^-4 Omega cm) is lower, and good ohmic contact can be formed with the p-type ohmic contact layer.

According to the invention, higher carrier mobility and optical parameters can be obtained by adjusting the proportion of doping elements in doped ZnO and adjusting preparation parameters.

Ga-O bond and Al-O in GZO (Ga-doped ZnO transparent conductive film) adopted by the inventionAnd In-OIn contrast, ga-O covalent bond length +.>Very close to Zn-O bond length +.>Even in the case where the Ga concentration is very high, deformation of ZnO lattice can be minimized, and GZO is more stable because gallium has a greater electronegativity than aluminum.

According to the invention, through optimization of technological parameters of film deposition, the carrier concentration and mobility of the film are improved, the resistivity is reduced, the transmittance of the film is improved, the light absorption loss is reduced, and the performance of a photoelectric device is improved.

The present invention may use magnetron sputtering, electron beam evaporation, atomic layer deposition, pulsed laser deposition, etc., but is not limited to the above-described various methods.

The invention selects proper transparent conductive oxide, and the final effect is that the ohmic contact characteristic of the transparent conductive oxide and p-type GaN is as low as possible, and the absorption coefficient of the transparent conductive oxide is as low as possible, so as to improve the performance of the photoelectric device. A parameter can be used to deposit a film to obtain a uniform film; or different deposition condition combinations are adopted to form a plurality of layers of film combinations with different properties; the metal oxide is a ZnO film doped with different elements, and one or more elements can be selected to be doped into ZnO, such as Aluminum Zinc Oxide (AZO), gallium Zinc Oxide (GZO), indium Zinc Oxide (IZO), magnesium Zinc Oxide (MZO), indium Gallium Zinc Oxide (IGZO) and the like.

It should be understood that the doped ZnO transparent conductive oxide layer in the present invention may be a binary metal oxide, or may be a ternary metal oxide, or may be two or more binary metal oxides, or may be two or more ternary metal oxides, or may be formed by using one or more binary metal oxides and one or more ternary metal oxides together, and include a structure in which a component formed by growing a metal oxide is abrupt or a component is gradually changed.

It should be understood that the above embodiments are merely for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the present invention and implement the same according to the present invention without limiting the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.

Claims

1. A GaN-based photoelectric device comprising a first optical confinement layer, a first waveguide layer, an active layer, a second waveguide layer, an electron blocking layer, a second optical confinement layer, and an ohmic contact layer, which are sequentially stacked in a selected direction, characterized by further comprising:

2. The GaN-based optoelectronic device of claim 1, wherein: the doped ZnO layer contains at least one of Al element, ga element, in element, mg element, mn element and B element, and the mass percentage ratio of the doped element to Zn element In the doped ZnO layer is (2-0 wt%): (98 wt% -90 wt%).

3. The GaN-based optoelectronic device of claim 2, wherein: the mass percentage of the doping elements in the doped ZnO layer is gradually changed or suddenly changed along the selected direction;

preferably, the mass percentage of the doping element in the doped ZnO layer is 2-8wt%.

4. A GaN-based optoelectronic device as claimed in claim 3 wherein: the doped ZnO layer comprises at least two sub-layers which are stacked along the selected direction, wherein at least one of the types and the mass percentages of doping elements in the at least two sub-layers are different;

preferably, the doped ZnO layer includes a first doped ZnO layer and a second doped ZnO layer sequentially stacked on the ohmic contact layer along the selected direction, the doped elements contained in the first doped ZnO layer and the second doped ZnO layer are the same or different, and the doped elements contained in the first doped ZnO layer and the second doped ZnO layer are different in mass percentage;

preferably, the mass percentage of the doping element contained in the first doped ZnO layer is larger than the mass percentage of the doping element contained in the second doped ZnO layer;

preferably, the mass percentage of the doping element contained in the first doped ZnO layer is 8wt%, and the mass percentage of the doping element contained in the second doped ZnO layer is 2wt%.

5. A GaN-based optoelectronic device as claimed in claim 3 wherein: the mass percentage of the doping element in the doped ZnO layer is gradually decreased from 8wt% to 2wt% along the direction away from the ohmic contact layer;

preferably, the gradient of the mass percent of the doping element in the doped ZnO layer is 8-2 wt%.

6. A GaN-based optoelectronic device as claimed in claim 3 wherein: the doped ZnO layer contains a doped element of Al, and the mass percentage ratio of Zn element to Al element in the doped ZnO layer is (98-92 wt%);

7. The GaN-based optoelectronic device of claim 1, wherein: the thickness ratio of the second light limiting layer to the doped ZnO layer is (2-5) to (1-3);

preferably, the thickness of the second light limiting layer is 200-400 nm;

preferably, the thickness of the doped ZnO layer is 100-300 nm.

8. The GaN-based optoelectronic device of claim 1, wherein: the electron blocking layer, the second light limiting layer and the ohmic contact layer are of a first conductivity type, the doped ZnO layer and the first light limiting layer are of a second conductivity type, the first conductivity type is of a P type, and the second conductivity type is of an N type;

preferably, the materials of the first light limiting layer, the first waveguide layer, the active layer, the second waveguide layer, the electron blocking layer and the ohmic contact layer are all GaN-based semiconductor materials;

preferably, the second light confinement layer comprises p-AlxGa _l-x N layer or p-Al _x Ga _1-x N/GaN superlattice.

9. The GaN-based optoelectronic device of claim 1, comprising n-Al stacked in a selected direction _x Ga _1-x N-optical confinement layer, N-InGaN waveguide layer, in _x Ga _1-x N/GaN quantum well active layer, undoped u-In _x Ga _1-x N waveguide layer, p-Al _x Ga _1-x N electron blocking layer, p-Al _x Ga _1-x An N/GaN superlattice light limiting layer, a p-GaN ohmic contact layer and a doped ZnO layer.

10. The GaN-based optoelectronic device of claim 1 wherein the first light confining layer is disposed on a buffer layer disposed on a substrate.