CN117353154A - GaN-based optoelectronic devices - Google Patents

Abstract

The invention discloses a GaN-based optoelectronic device. The GaN-based optoelectronic device includes 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, an ohmic contact layer and doped ZnO that are stacked sequentially along a selected direction. layer, the doped ZnO layer is stacked on the ohmic contact layer along the selected direction, the doped ZnO layer forms an ohmic contact with the ohmic contact layer, and the doped ZnO layer also has Optical confinement effect. The invention reduces the operating voltage of the optoelectronic device, increases the output efficiency, and improves the performance of the optoelectronic device.

Description

GaN-based optoelectronic devices

Technical field

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

Background technique

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 made great progress, resulting in the device performance of gallium nitride (GaN)-based optoelectronic devices, such as laser diodes, light-emitting diodes, power devices and purple photodetectors, etc. improvement. Especially in recent years, GaN-based lasers have been widely used in biochemical analysis, full-color display, laser processing, high-density storage, laser pumping and laser lithography.

Traditional semiconductor lasers include structures such as a substrate, a lower light confinement layer, a lower waveguide layer, a quantum well active area, a waveguide layer, an upper light confinement layer, and a metal contact layer. The upper light confinement layer uses aluminum gallium nitride (AlGaN) or aluminum gallium nitride/gallium nitride superlattice to confine light in the quantum well active area, and the contact metal uses palladium/platinum/gold (Pd/Pt/Au) or Metal combinations such as titanium/gold (Ti/Au) form ohmic contacts with p-type GaN.

To meet the requirements of a wide range of applications, GaN lasers require higher output power, lower resistance and better thermal stability. There are many factors that affect the performance of laser devices, such as material quality, ohmic contact, cleavage, facet coatings, etc. 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 generally use p-type aluminum gallium nitride or aluminum gallium nitride/gallium nitride superlattice as the upper light confinement layer. However, there are several problems: (1) Tensile stress will be generated during the growth of the light confinement layer on p-type aluminum gallium nitride or p-type aluminum gallium nitride/gallium nitride superlattice, resulting in cracking of the epitaxial wafer. This characteristic 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 p-type aluminum gallium nitride or p-type aluminum gallium nitride/gallium nitride superlattice is usually above 900°C, which is higher than the growth temperature of the quantum well active region, which will cause quantum Well degradation affects laser performance. (3) The resistivity of the light confinement layer on the p-type aluminum gallium nitride or p-type aluminum gallium nitride/gallium nitride superlattice is high, which is the main source of series resistance of the gallium nitride-based laser, making the operating voltage of the laser very high. high. (4) The hole concentration of the p-type AlGaN layer is low and the sheet resistance is large, resulting in a small hole injection area on the p-side and a large current density per unit area. Severe heating will occur under large current injection, which is detrimental to device life and reliability. , unable to obtain high output power. Therefore, it is necessary to solve these problems of GaN-based LDs. It is necessary to find a method that can limit the light field, obtain stable oscillation, and at the same time reduce resistance and stabilize p-type GaN ohmic contacts to improve the luminous efficiency of blue-green LDs.

In existing research, tin-doped indium oxide (ITO) in transparent conductive oxide (TCO) is commonly used to replace the AlGaN layer or AlGaN/GaN superlattice layer. However, ITO has limitations and shortcomings: the surface work function of the ITO film is in Between 4.6-4.9eV, in optoelectronic devices, the work function of the anode electrode material is relatively low, and the work function of the cathode is relatively high. There is a carrier energy level difference between the material and the functional layer, creating a potential barrier, resulting in carrier injection efficiency. Low, affecting the performance of the device; in OLED, the diffusion of In in the ITO electrode in the organic functional layer also affects the service life of the device; in solar cell applications, the surface roughness and surface resistance of ITO films are poor, and further work is still needed. Improvement; the indium element in ITO films is difficult to purify due to low earth reserves. Currently, with the massive market demand and use, the price has been rising repeatedly. At the same time, In has become a scarce material and is facing depletion.

At present, folding mobile phone screens has become a hot topic, and there are high requirements for flexible and bendable TCO films. ITO films are not resistant to bending and have obvious shortcomings. To prepare high-performance ITO films, the preparation conditions are very demanding. ITO films are highly dependent on target materials. High-quality targets have very high requirements on raw materials and sputtering target preparation processes, and target life and density are critical. factor.

Contents of the invention

The main purpose of the present invention is to provide a GaN-based optoelectronic device to overcome the shortcomings of the existing technology.

In order to achieve the foregoing invention objectives, the technical solutions adopted by the present invention include:

The invention provides a GaN-based optoelectronic device, which includes a first light confinement layer, a first waveguide layer, an active layer, a second waveguide layer, an electron blocking layer, a second light confinement layer and a first light confinement layer, which are sequentially stacked along a selected direction. The ohmic contact layer, as well, also includes:

a doped ZnO layer, the doped ZnO layer is stacked on the ohmic contact layer along the selected direction, the doped ZnO layer forms an ohmic contact with the ohmic contact layer, and the doped ZnO layer The layer also has an optical confinement effect.

The present invention uses a doped ZnO layer and an aluminum gallium nitride layer to synergize as the optical confinement layer. The light field confinement effect is stronger than that of a thick aluminum gallium nitride layer alone as the optical confinement layer. The optical loss is lower, and the light field is better confined in the quantum well. .

Further, the doping elements contained in the doped ZnO layer include at least one of Al element, Ga element, In element, Mg element, Mn element, and B element, and the doping in the doped ZnO layer The ratio of the mass percentage of the element and the Zn element is (2wt%~10wt%): (98wt%~90wt%).

Further, the inventor of this case has found that too much of Ga and other doping elements will cause the transmittance of the thin film (i.e., the doped ZnO layer) to decrease, and at the same time cause the absorption coefficient of the thin film to increase, causing photoelectric devices (LD) The optical loss increases, and if the atomic ratio of doping elements such as Ga is too low, the resistivity of the film will increase, resulting in an increase in the series resistance of the optoelectronic device. Therefore, choosing the appropriate ratio of Zn:Ga and other doping elements is As the key to the LD confinement layer. The inventor of this case found that the doping amount of Ga and other elements affects the carrier concentration and mobility of the film, which in turn affects the resistivity of the film. As the doping amount of Ga and other elements increases, the resistivity will first decrease and then increase. High carrier concentration is conducive to the formation of good ohmic contact. Due to the scattering effect of Ga and other elements, the transmittance and absorption coefficient of the film will change. The doping amount of Ga and other elements affects the absorption coefficient of the film. The appropriate doping amount of Ga and other elements is beneficial to the power of the laser. promote.

Further, the mass percentage of the doping element in the doped ZnO layer gradually changes or changes suddenly along the selected direction.

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

Further, the doped ZnO layer includes at least two sub-layers stacked along the selected direction, and at least one of the type and mass percentage of the doping elements in the at least two sub-layers is different.

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

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

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

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

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

Further, the doping element contained in the doped ZnO layer is Al element, and the mass percentage ratio of the Zn element to the Al element in the doped ZnO layer is (98wt% ~ 92wt%): (2wt% ~ 8wt %);

Alternatively, the doping element contained in the doped ZnO layer is Ga element, and the mass percentage ratio of the Zn element to the Ga element in the doped ZnO layer is (92wt%~98wt%): (8wt%~2wt% );

Alternatively, the doping 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 (90wt%~98wt%): (10wt%~2wt%);

Alternatively, the doping 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 (90wt%~98wt%): (10wt%~2wt%);

Alternatively, the doping elements contained in the doped ZnO layer are Ga element and In element, and the mass percentage of the Zn element, Ga element, and In in the doped ZnO layer is (90wt%~98wt%): (10wt% ~1wt%): (10wt%~1wt%).

The doped ZnO layer (taking GZO as an example) in the present invention is on the optical confinement layer of the grown ohmic contact layer (p-GaN (about 20nm) + p-InGaN (about 3-10nm)).

For example, the doped layer GZO can be divided into two sub-layers with different element doping contents. The first layer uses GZO with a higher Ga doping concentration (for example, Ga: 5wt%), and the thickness is about 100nm. The second layer uses GZO with a relatively low Ga doping concentration (for example, Ga: 2wt%), and the thickness is about 100nm. The first layer uses a high doping concentration to form a better ohmic contact, and the second layer uses a low doping concentration to obtain better optical properties. During production, magnetron sputtering or electron beam evaporation can be used to deposit thin films, using two targets with different doping concentrations to deposit them respectively.

The Ga element in the doped layer GZO can change in a gradient, and the concentration of the Ga element (ie, mass percentage, the same below) can gradually change from 8wt% to 2wt%. Specifically, magnetron sputtering or electron beam evaporation can be used to deposit the film, using two targets with different doping concentrations (for example, Ga: 8wt% and Ga: 2wt%) to co-deposit, and the two targets are sputtered at the same time. By adjusting the sputtering power of the two targets, the effect of doping concentration gradient change is achieved.

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

In other specific embodiments, two or more conductive oxide layers can be combined as the doped ZnO layer, that is, the doped ZnO layer can include multiple sub-layers with different element doping types. For example, the first layer is 50nm. ITO (95wt% In ₂ O ₃ and 5wt% SnO ₂ or 90wt% In ₂ O ₃ and 10wt% SnO ₂ ), the second layer is GZO or AZO (other doped ZnO layers, etc.) with a thickness of 100~300nm, Alternatively, the first layer is ITO (95wt% In ₂ O ₃ and 5wt% SnO ₂ or 90wt% In ₂ O ₃ and 10wt% SnO ₂ ) with a thickness of 50nm, the second layer is GZO with a thickness of 50nm, and the third layer is AZO (other doped ZnO layers, etc.) with a thickness of 100~300nm.

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

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

Further, the thickness of the second light confinement 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 confinement layer and the ohmic contact layer are all of the first conductivity type, the doped ZnO layer and the first light confinement layer are of the second conductivity type, and the third One conductivity type is P type, and the second conductivity type is N type.

Further, the first light 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 includes a p-AlxGa _1-x N layer or a p-Al _x Ga _1-x N/GaN superlattice.

In a more specific embodiment, the GaN-based optoelectronic device includes an n-Al _x Ga _1-x N optical confinement layer, an n-InGaN waveguide layer, _{and In} 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 super Lattice light confinement layer, p-GaN ohmic contact layer and doped ZnO layer.

Further, the first light confinement layer is disposed on the buffer layer, and the buffer layer is disposed on the substrate.

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

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

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

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

Further, _the electron blocking layer _may be a _p - _Al % to 30%, and its hole concentration is between 10 ¹⁷ cm ^-3 and 10 ²⁰ cm ^-3 .

Further, the second optical confinement layer includes a stacked p-Al _x Ga _1-x N/GaN superlattice layer or a p-Al _x Ga _1-x N optical confinement layer, p-Al _x Ga _{1- The x} N/GaN superlattice layer includes 10 to 500 periods, its hole concentration is between 10 ¹⁷ cm ^-3 and 10 ²⁰ cm ^-3 , and the Al component content is 10% to 30%.

Further, the ohmic contact layer 9 uses a heavily doped GaN:Mg layer with a thickness of 10 nm to 30 nm, and the Mg doping concentration is between 10 ¹⁹ cm ^-3 and 10 ²¹ cm ^-3 .

In some more typical implementations, the GaN _- based optoelectronic device includes n-Al _x Ga _1-x N optical confinement layer, n-InGaN waveguide layer, _In 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 super Lattice light confinement layer, p-GaN ohmic contact layer.

Further, the first light confinement layer is disposed on the buffer layer, and the buffer layer is disposed on the substrate.

Further, the materials of the substrate and the buffer layer are both GaN-based semiconductor materials. Further, the substrate can be an n-GaN substrate, the buffer layer can be an n-GaN buffer layer, and the n- The thickness of the GaN buffer layer is 0nm to 3000nm, and its electron concentration is between 10 ¹⁷ cm ^-3 and 10 ²⁰ cm ^-3 .

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

Further, the GaN-based optoelectronic devices include LEDs, solar cells, detectors, display screens, etc.

Compared with the existing technology, the advantages of the present invention include:

The present invention reduces the thickness of the traditional p-type AlGaN or AlGaN/GaN superlattice light confinement layer, and uses doped ZnO transparent conductive oxide to replace part of the light confinement layer and electrode layer, thereby reducing the operating voltage of the optoelectronic device and increasing the The output efficiency is improved and the performance of the optoelectronic device is improved.

By optimizing the process parameters of film deposition, the present invention improves the carrier concentration and mobility of the film, obtains low resistivity, increases the transmittance of the film, reduces the absorption coefficient, and improves the performance of the optoelectronic device.

Description of drawings

Figure 1 is a schematic structural diagram of a GaN-based laser provided in a typical implementation case of the present invention.

Detailed ways

In view of the deficiencies in the prior art, the inventor of this case was able to propose the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principles will be further explained below with reference to the accompanying drawings and specific implementation cases. Unless otherwise specified, the semiconductor film forming processes used in the embodiments of the present invention are all technologies in the art. Personnel known.

The development of efficient InGaN laser diodes (LD) is considered one of the most important topics in the fields of laser display and laser communications. Transparent conductive oxide TCOs, such as indium tin oxide ITO, have high transparency in the visible light region, low refractive index and absorption coefficient, and small lattice mismatch with GaN, making them capable of serving as light confinement layers in LDs. Although ITO has been widely used as the optical confinement layer of LD, which has the function of limiting the light field and reducing optical loss, due to the scarcity of indium on the earth and the increase in price, it is very important to find alternatives.

ZnO-based TCO (transparent conductive oxide) is a wide band gap material, and it is also a non-toxic material that can be eaten by the human body. It has similar electrical and optical transmission properties to ITO. For example, using gallium-doped ZnO can obtain a thin film with low resistivity and high transmittance in the visible light region. It has the following advantages when used in GaN and Ga ₂ O ₃ -based materials and devices. Advantages: 1) Covalent bond length of Ga-O Covalent bond length with Zn-O/> It is also very close. The introduction of Ga into the crystal structure of ZnO produces minimal lattice distortion and is bound to be more stable. The GaN in the substrate material is the same as the Ga in doped GZO. When preparing a TCO/GaN heterostructure, the use of a GZO film is beneficial to reducing the Defects introduced by lattice mismatch between TCO and GaN-based materials. 2) Ga in GaN easily diffuses outward under the influence of temperature, and entering ZnO helps to improve the conductive properties and further reduce the series resistance. 3) Compared with ITO materials, the refractive index of doped ZnO is lower, which is beneficial to reducing light loss. On the one hand, the cost of using ITO alone is relatively high. On the other hand, ITO not only has a large lattice mismatch with GaN and is prone to defects, but the refractive index and absorption coefficient of ITO are greater than those of doped ZnO, resulting in increased optical losses. These are not conducive to device performance and reduce service life.

In the present invention, after the growth of the epitaxial wafer of the optoelectronic device is completed, a ZnO:Ga transparent conductive oxide film is deposited on the ohmic contact layer as a doped ZnO layer. The doped ZnO layer simultaneously serves as a part of the ohmic contact layer and the second light confinement layer. part. When depositing ZnO:Ga, the growth equipment can be connected to the deposition equipment through an ultra-high vacuum pipeline, and the sample can be transferred into the deposition equipment to deposit GZO, or plasma equipment (for example, N _plasma ) can be used to process the sample surface, and the sample can be transferred into the deposition equipment. Deposition equipment deposits GZO, or uses wet cleaning (including organic cleaning and inorganic cleaning) to treat the surface and transfer it to the deposition equipment to deposit GZO. After the film is deposited, the sample is annealed and the appropriate atmosphere, temperature and time are selected.

Specifically, during the deposition process, ZnO:Ga ₂ O ₃ =95:5 (mass percentage ratio). If the ratio of Ga atoms is too high, the transmittance of the film will decrease, and the absorption coefficient of the film will increase, causing The optical loss of LD increases. Too low a Ga atomic ratio will cause the film resistivity to increase, resulting in an increase in the series resistance of the optoelectronic device. Therefore, choosing the appropriate Zn:Ga ratio is the key to serving as the LD confinement layer. Oxygen in the environment during the process preparation has the same effect. Its content and ratio not only change the optical transmission and refraction parameters, adjust the optical properties, but also affect the electrical properties of the film. For example, excessive oxygen causes the resistivity to rise. High, which increases the power usage of the device and increases the risk of reduced device life.

Specifically, In ₂ O ₃ has high transmittance (visible light region transmittance > 80%), carrier concentration of 10 ²¹ cm ^-3 , Hall mobility 10-100cm ² /Vs, and low resistance. The rate is on the order of 10 ^-4 Ω·cm, the band gap is about 3.5-4.3eV, the work function is about 4.6-4.9eV, the bandgap width of ZnO at room temperature is 3.4eV, the average visible light transmittance is about 90%, and the resistivity 10 ^-4 Ωcm, Hall mobility is about 40cm ² /Vs. The ZnO:Ga film is more likely to form ohmic contact with the InGaN contact layer of the LD, reducing defects introduced by the lattice mismatch between TCO and GaN-based materials. Compared with ITO materials, the refractive index of doped ZnO is lower, which is beneficial to reducing Optical loss reduces the threshold voltage.

The doped ZnO layer in the present invention can also be obtained by sputtering coating using the magnetron sputtering method. The specific parameters of the sputtering coating using the magnetron sputtering method are: the background vacuum is generally 10 ^-8 torr, and the ultra-high vacuum environment It can ensure that the film is pure during the sputtering process and will not be doped with impurities such as H ₂ O and O ₂ . Choose an appropriate sputtering pressure. If the pressure is too low, the sputtering rate will decrease. If the pressure is too high, the film grains will be too large. The sputtering mode uses optimized RF mode and DC mode. The RF mode causes less sputtering damage to the substrate, but the growth rate will be slower. Although the DC mode causes greater sputtering damage to the substrate, the growth rate is faster. . The sputtering power needs to be selected appropriately. If the power is too high, it will cause greater sputtering damage, while if the power is too low, the efficiency will be low. Generally, choosing a suitable temperature for the substrate temperature can increase the migration of sputtered particles. An increase in temperature will slow down the deposition rate and also cause oxidation of the sample surface. The deposition thickness is generally chosen to be a suitable thickness (for example, about 200nm). If the thickness is too thin or too thick, it will not be able to form a good restriction on the light field. After depositing the GZO film on the LD surface, select the appropriate annealing temperature, atmosphere and time (for example, the annealing temperature is 300°C and the annealing time is 5 minutes). The temperature is too low to allow Zn to diffuse into the interior of InGaN and increase the carrier concentration. The temperature is too low. High, leading to the formation of Ga ₂ O ₃ and ZnGaO oxides, resulting in the formation of additional barriers at the interface, which is not conducive to the formation of ohmic contacts.

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

Example 1

Please refer to Figure 1. A GaN-based optoelectronic device includes an n-GaN substrate 10, an n-GaN buffer layer, an n-Al _x Ga _1-x N optical confinement layer 20, and 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 N optical confinement layer 70 and p-GaN/InGaN ohmic contact layer 80 and doped ZnO layer 90 .

In this embodiment, the thickness of the n-GaN buffer layer is 1000 nm, its electron concentration is 10 ¹⁸ cm ^-3 , the thickness of the n-Al _x Ga _1-x N confinement layer 20 is 800 nm, and the content of the Al component is 5%, its electron concentration is 10 ²⁹ cm ^-3 , the thickness of the n-In _x Ga _1-x N waveguide layer 30 is 50 nm, the content of the In component is 4%, and its electron concentration is 10 ¹⁸ cm ^-3 , The active layer 40 may include 5 periods of undoped _{In x} Ga _{1 -x} N/GaN quantum wells. The thickness of the In The thickness of the barrier is 2nm, the thickness of the undoped u- _InxGa1 - _xN waveguide layer 50 is 40nm, the In component content is 2%, and the thickness of the p- _{AlxGa1 -xN} electron blocking layer 60 is 10nm nm, the composition content of Al is about 10%, its hole concentration is 10 ¹⁷ cm ^-3 , the thickness of the p-Al _x Ga _1-x N optical confinement layer 70 is 200 nm, and the p-GaN/InGaN ohmic contact layer The thickness of the p-GaN layer in 80 is 10nm~30nm, the Mg doping concentration is 10 ²⁰ cm ^-3 , the thickness of the p-InGaN contact layer is 3~10nm, and the Mg doping concentration is 10 ²⁰ cm ^-3 .

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

Example 2

Please refer to Figure 1. The structure of a GaN-based optoelectronic device in Embodiment 2 is basically the same as that in Embodiment 1. The difference is that in this embodiment, the thickness of the doped ZnO layer is 250 nm.

Example 3

Please refer to Figure 1. The structure of a GaN-based optoelectronic device in Embodiment 3 is basically the same as that in Embodiment 1. The difference is that in this embodiment, the thickness of the doped ZnO layer is 300 nm.

Example 4

Please refer to Figure 1. The structure of a GaN-based optoelectronic device in Embodiment 4 is basically the same as that in Embodiment 1, except that:

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

Example 5

Please refer to Figure 1. The structure of a GaN-based optoelectronic device in Embodiment 5 is basically the same as that in Embodiment 1, except that:

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

Example 6

Please refer to Figure 1. The structure of a GaN-based optoelectronic device in Embodiment 6 is basically the same as that in Embodiment 1, except that:

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

Example 7

Please refer to Figure 1. The structure of a GaN-based optoelectronic device in Embodiment 7 is basically the same as that in Embodiment 1, except that:

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

Example 8

Please refer to Figure 1. The structure of a GaN-based optoelectronic device in Embodiment 8 is basically the same as that in 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 50 nm. The doping element is Al, and the mass percentage of the Al element is 5 wt%. The thickness of the second doped ZnO layer is 50 nm. The doping element in the second doped ZnO layer is Al, and the mass percentage of the Al element is 2 wt%.

Comparative example 1

Please refer to Figure 1. The structure of a GaN-based optoelectronic device in Comparative Example 1 is basically the same as that in Embodiment 1, except that:

In this comparative example, the doping element of the ZnO layer is Ga, and the mass percentage of the Ga element is 10 wt%.

Comparative example 2

Please refer to Figure 1. The structure of a GaN-based optoelectronic device in Comparative Example 2 is basically the same as that in Embodiment 1, except that:

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

Comparative example 3

Please refer to Figure 1. The structure of a GaN-based optoelectronic device in Comparative Example 5 is basically the same as that in Embodiment 1. The difference is that in this comparative example, ITO is used to replace the doped ZnO layer.

The present invention uses ZnO-based doped ZnO as a TCO film to replace part of the AlGaN layer or AlGaN/GaN superlattice layer, and forms a light confinement layer together with the AlGaN layer or AlGaN/GaN superlattice. 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), etc.

Since both ZnO and GaN have the same wurtzite crystal structure with only a small lattice mismatch of about 1.8%, doping the lattice between ZnO and the GaN-based AlGaN layer or AlGaN/GaN superlattice layer The mismatch is small, and the GaN-based optoelectronic devices formed by this have higher stability and reliability. ZnO has a very high transparency (usually more than 90% in the visible light range), which can effectively reduce optical losses. By adjusting the proportion of doping elements, its own optical parameters and electrical properties can be adjusted. The resistivity of the doped ZnO film (usually (approximately 2×10 ^-4 Ω·cm) is lower, and it can also form good ohmic contact with the p-type ohmic contact layer.

The present invention can obtain higher carrier mobility and optical parameters by adjusting the proportion of doping elements in doped ZnO and adjusting the preparation parameters.

The Ga-O bond and Al-O in the GZO (Ga-doped ZnO transparent conductive film) used in the present invention and In-O Compared to Ga-O covalent bond length/> Very close to the Zn-O bond length/> Deformation of the ZnO lattice is minimized even at very high Ga concentrations, and, because gallium has greater electronegativity compared to aluminum, GZO is more stable.

The present invention reduces the thickness of the traditional p-type AlGaN or AlGaN/GaN superlattice light confinement layer, and uses doped ZnO transparent conductive oxide to replace part of the light confinement layer and electrode layer, thereby reducing the operating voltage of the optoelectronic device and increasing the The output efficiency is improved and the performance of the optoelectronic device is improved.

By optimizing the process parameters of thin film deposition, the present invention improves the carrier concentration and mobility of the thin film, reduces the resistivity, simultaneously increases the transmittance of the thin film, reduces the light absorption loss, and improves the performance of the optoelectronic device.

The present invention can use magnetron sputtering, electron beam evaporation, atomic layer deposition, pulse laser deposition and other methods but is not limited to the above methods.

The present invention selects a suitable transparent conductive oxide. The final effect is that the ohmic contact characteristics of the transparent conductive oxide and p-type GaN are as low as possible, and the absorption coefficient of the transparent conductive oxide is as small as possible, thereby improving the performance of the optoelectronic device. Way. One parameter can be used to deposit the film to obtain a uniform film; or different combinations of deposition conditions can be used to form a multi-layer film combination with different properties; the metal oxide is a ZnO film doped with different elements, and one or more can be selected. Various elements are 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), etc.

It should be understood that the doped ZnO transparent conductive oxide layer in the present invention can be a binary metal oxide, a ternary metal oxide, or two or more binary metal oxides. It can also be two or more ternary metal oxides, or it can be formed together by more than one binary metal oxide and more than one ternary metal oxide, and includes component mutations formed by the growth of metal oxides or Structure with gradients of components.

It should be understood that the above embodiments are only to illustrate the technical concepts and characteristics of the present invention. Their purpose is to enable those familiar with the technology to understand the content of the present invention and implement it accordingly, and cannot limit the scope of protection of the present invention. All equivalent changes or modifications made based on the spirit and essence of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A GaN-based optoelectronic 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 that are stacked sequentially along a selected direction. The layer is also characterized by: a doped ZnO layer, the doped ZnO layer is stacked on the ohmic contact layer along the selected direction, the doped ZnO layer forms an ohmic contact with the ohmic contact layer, and the doped ZnO layer The layer also has an optical confinement effect. 2. The GaN-based optoelectronic device according to claim 1, wherein the doping elements contained in the doped ZnO layer include at least one of Al element, Ga element, In element, Mg element, Mn element and B element. One kind, and the ratio of the mass percentage of the doping element and the Zn element in the doped ZnO layer is (2wt%~10wt%): (98wt%~90wt%). 3. The GaN-based optoelectronic device according to claim 2, characterized in that: the mass percentage of the doping element in the doped ZnO layer changes gradually or suddenly along the selected direction; Preferably, the mass percentage of the doping element in the doped ZnO layer is 2 to 8 wt%. 4. The GaN-based optoelectronic device according to claim 3, wherein the doped ZnO layer includes at least two sub-layers stacked along the selected direction, and the types of doping elements in the at least two sub-layers Different from at least one of the mass percentages; 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, and the first doped ZnO layer and The doping elements contained in the second doped ZnO layer are the same or different, and the mass percentages of the doping elements contained in the first doped ZnO layer and the second doped ZnO layer are different; Preferably, the mass percentage of the doping elements contained in the first doped ZnO layer is greater than the mass percentage of the doping elements contained in the second doped ZnO layer; Preferably, the mass percentage of the doping elements contained in the first doped ZnO layer is 8 wt%, and the mass percentage of the doping elements contained in the second doped ZnO layer is 2 wt%. 5. The GaN-based optoelectronic device according to claim 3, characterized in that: the mass percentage of the doping element in the doped ZnO layer gradually decreases from 8wt% to 2wt% in a direction away from the ohmic contact layer; Preferably, the gradient of the mass percentage of the doping element in the doped ZnO layer is 8 wt% to 2 wt%. 6. The GaN-based optoelectronic device according to claim 3, characterized in that: the doping element contained in the doped ZnO layer is Al element, and the mass percentage of the Zn element in the doped ZnO layer and the Al element is The ratio is (98wt%～92wt%): (2wt%～8wt%); Alternatively, the doping element contained in the doped ZnO layer is Ga element, and the mass percentage ratio of the Zn element to the Ga element in the doped ZnO layer is (92wt%~98wt%): (8wt%~2wt% ); Alternatively, the doping 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 (90wt%~98wt%): (10wt%~2wt%); Alternatively, the doping 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 (90wt%~98wt%): (10wt%~2wt%); Alternatively, the doping elements contained in the doped ZnO layer are Ga element and In element, and the mass percentage of the Zn element, Ga element, and In in the doped ZnO layer is (90wt%~98wt%): (10wt% ~1wt%): (10wt%~1wt%). 7. The GaN-based optoelectronic device according to claim 1, characterized in that: the ratio of the thickness of the second light confinement layer and the doped ZnO layer is (2~5): (1~3); Preferably, the thickness of the second light limiting layer is 200-400nm; Preferably, the thickness of the doped ZnO layer is 100-300 nm. 8. The GaN-based optoelectronic device according to claim 1, characterized in that: the electron blocking layer, the second light confinement layer and the ohmic contact layer are all of the first conductivity type, and the doped ZnO layer and the The first light confinement layer is of a second conductivity type, the first conductivity type is P type, and the second conductivity type is N type; Preferably, the first light 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 material. ; Preferably, the second light confinement layer includes a p-AlxGa _lx N layer or a p- _Alx Ga _1-x N/GaN superlattice. 9. The GaN _- based optoelectronic device according to claim ₁ , characterized in that it includes _{n -} Al _-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 optical confinement layer, p-GaN ohmic contact layer and doped ZnO layer. 10. The GaN-based optoelectronic device according to claim 1, wherein the first light confinement layer is provided on a buffer layer, and the buffer layer is provided on a substrate.