AlGaN Ultraviolet Light-Emitting Diodes and Lasers with p-NiO as the Cap Layer and Their Preparation Methods

Abstract

An AlGaN ultraviolet light-emitting diode and laser with p-NiO as the cap layer and its manufacturing method, belonging to the technical field of semiconductor light-emitting devices and their manufacturing. The device is successively composed of a substrate, an Al y Ga 1‑y N epitaxial lower confinement layer, an Al x Ga 1‑x N material multiple quantum well active light-emitting layer, an Al z Ga 1‑z N electron confinement layer, a cap layer, an upper electrode and a lower electrode; the cap layer is p-NiO, and the hole concentration can be as high as 10 18 ~10 20 / cm 3 . By utilizing the characteristics of p-NiO such as high hole concentration, low resistivity and low refractive index, the present invention can form good hole injection for the device and good confinement for light, and has the advantages of low working voltage, high luminous efficiency, and easy continuous lasing of the laser at room temperature, and can provide an ultraviolet light-emitting tube and laser with a shorter wavelength than that using only the AlGaN material system.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor light-emitting devices and their preparation, and particularly relates to an AlGaN ultraviolet light-emitting diode and laser with a p-NiO capping layer and a preparation method thereof. Background Art

[0002] Ultraviolet light-emitting diodes and lasers have extensive applications in the fields of information storage, biology and medicine, and military. Currently, semiconductor light-emitting diodes and lasers in this wavelength band are mainly prepared from GaN material systems.

[0003] However, the active region of GaN-based ultraviolet semiconductor light-emitting diodes and lasers is AlGaN material containing Al. In order to well confine the light and carriers in the active region, the electron confinement layer and the capping layer (light confinement layer and hole injection layer) above the active region must use AlGaN materials with a higher Al component content. Since the ionization energy of Mg acceptors in p-AlGaN increases with the increase of the Al component, the resistance of AlGaN with a high Al component is very large, the operating voltage of the light-emitting diode and the laser is relatively high, and it is very difficult to sputter the prepared ultraviolet laser. Even if sputtered, it is very difficult to achieve continuous operation at room temperature, and the luminous efficiency of the prepared ultraviolet light-emitting diode is also relatively low. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above difficulties of GaN-based ultraviolet light-emitting diodes and lasers, and utilize the characteristics of high hole concentration, low resistivity, and low refractive index of p-NiO to provide an AlGaN ultraviolet light-emitting diode and laser with a p-NiO capping layer (light confinement layer and hole injection layer) and a preparation method thereof. The p-NiO prepared by the present invention has a hole concentration as high as 10 18 ~10 20 / cm 3 , the resistivity is very low, only 2 - 4 Ω·cm (see Table 1). At the same time, the refractive index of NiO is almost the same as that of AlN, and it can completely confine the light emitted by the Al x Ga 1-x N active light-emitting layer with an x value below 0.7, so as to improve the luminous efficiency of the light-emitting diode and achieve low-voltage laser output of the laser device.

[0005] The technical solution of the present invention is as follows:

[0006] The AlGaN ultraviolet light-emitting diode designed by the present invention with a p-NiO capping layer (light confinement layer and hole injection layer) (see the attached Figure 1 and the accompanying drawings for description) is successively composed of a substrate 1, a GaN buffer layer 12 prepared on the substrate 1, and an n-type Si-doped layer (the carrier concentration range is 1×10 18 / cm3 ~9.9×10 19 / cm 3 Al of y Ga 1-y N epitaxial lower confinement layer (light, hole confinement layer and electron injection layer) 2, Al y Ga 1-y Discrete Al prepared on top of N epitaxial lower confinement layer 2 x Ga 1-x N material multiple quantum well active light-emitting layer 3 and lower electrode 7, Al x Ga 1-x p-type Mg-doped (carrier concentration range of 1×10 17 / cm 3 ~5×10 18 / cm 3 Al of z Ga 1-z N electron confinement layer 4, Al z Ga 1-z Cover layer (light confinement layer and hole injection layer) 5 prepared on N electron confinement layer 4, upper electrode 6 prepared on top of cover layer 5, characterized in that: substrate 1 is an Al2O3 or Si crystal wafer; cover layer (light confinement layer and hole injection layer) 5 is p-NiO, hole concentration is 1×10 18 / cm 3 ~9.9×10 20 / cm 3 . In order to further reduce the series resistance and simplify the process, the present invention designs an AlGaN ultraviolet light-emitting diode with p-NiO as the cover layer (light confinement layer and hole injection layer) and also as the electron confinement layer (see attached Figure 2 and the attached drawing description), successively composed of substrate 1, GaN buffer layer 12 prepared on top of substrate 1, n-type Si-doped (carrier concentration range of 1×10 18 / cm 3 ~9.9×10 19 / cm 3 Al of y Ga 1-y N epitaxial lower confinement layer (light, hole confinement layer and electron injection layer) 2, Al y Ga 1-y Discrete Al prepared on top of N epitaxial lower confinement layer 2 x Ga 1-x N material multiple quantum well active light-emitting layer 3 and lower electrode 7, Al x Ga 1-xIt is composed of a cover layer 5 prepared on the N material multi - quantum well active light - emitting layer 3 and an upper electrode 6 prepared on the cover layer 5. It is characterized in that: the substrate 1 is an Al2O3 or Si crystal wafer; the cover layer 5 is p - NiO, and the hole concentration is 1×10 18 / cm 3 ~9.9×10 20 / cm 3 .

[0007] The AlGaN ultraviolet laser designed in the present invention with p - NiO as the cover layer (light confinement layer and hole injection layer) (see the attached Figure 3 and the attached drawing description), which is successively composed of a substrate 1, an n - type Al 18 / cm 3 ~9.9×10 19 / cm 3 ) doped with Si (carrier concentration range) of the n - type Al y Ga 1-y N epitaxial lower confinement layer (light, hole confinement layer and electron injection layer) 2, an Al y Ga 1-y N epitaxial lower confinement layer 2 prepared with an Al x Ga 1-x N material multi - quantum well active light - emitting layer 3, an Al x Ga 1-x N material multi - quantum well active light - emitting layer 3 prepared with p - type Al 17 / cm 3 ~5×10 18 / cm 3 ) doped with Mg (carrier concentration range), a p - type Al z Ga 1-z N electron confinement layer 4, a cover layer (light confinement layer and hole injection layer) 5 prepared on the Al z Ga 1-z N electron confinement layer 4, an upper electrode 6 prepared on the cover layer 5, and a lower electrode 7 prepared under the substrate 1. It is characterized in that: the substrate 1 is an n - type SiC or n - type GaN crystal wafer (carrier concentration range is 1×10 18 / cm 3 ~9.9×10 19 / cm 3 ); the cover layer (light confinement layer and hole injection layer) 5 is p - NiO, and the hole concentration is 1×10 18 / cm 3 ~9.9×10 20 / cm 3 ; the front and rear end faces cleaved from the epitaxial wafer form a front mirror 8 and a rear mirror 9, and the light of the laser is in the Al x Ga 1-xAfter the N-material multi-quantum well active light-emitting layer 3 is generated, light is emitted by the front mirror 8 and the rear mirror 9 under the cover layer 5.

[0008] Furthermore, in order to confine the current injected into the laser to a strip region with a smaller area to reduce the threshold. The present invention proposes an AlGaN ultraviolet laser with a ridge stripe structure having p-NiO as the cover layer (light confinement layer and hole injection layer) (see the attached Figure 4 and the accompanying drawings), which successively consists of a substrate 1, an n-type Al 18 Ga 3 N epitaxial lower confinement layer (light and hole confinement layer and electron injection layer) 2 doped with Si (carrier concentration range is 1×10 19 / cm 3 ~9.9×10 y Ga 1-y N) prepared on the substrate 1, an Al y Ga 1-y N multi-quantum well active light-emitting layer 3 prepared on the Al x Ga 1-x N epitaxial lower confinement layer 2, an Al x Ga 1-x N multi-quantum well active light-emitting layer 3, a p-type Al 17 Ga 3 N electron confinement layer 4 doped with Mg (carrier concentration range is 1×10 18 / cm 3 ~5×10 z Ga 1-z N) prepared on the N multi-quantum well active light-emitting layer 3, and a lower electrode 7 prepared under the substrate 1. It is characterized in that: the substrate 1 is an n-type SiC or n-type GaN crystal wafer (carrier concentration range is 1×10 18 / cm 3 ~9.9×10 19 / cm 3 ); a ridge stripe structure cover layer (light confinement layer and hole injection layer) 5 is prepared on the Al z Ga 1-z N electron confinement layer 4. The cover layer (light confinement layer and hole injection layer) 5 is p-NiO, and the hole concentration is 1×10 18 / cm 3 ~9.9×10 20 / cm 3; A silicon dioxide current isolation layer 10 is prepared on the capping layer 5. A strip-shaped current limiting window 11 is prepared on the silicon dioxide current isolation layer 10 at the top of the ridge-shaped strip capping layer 5. An upper electrode 6 is prepared on the silicon dioxide current isolation layer 10 and the strip-shaped current limiting window 11. The upper electrode 6 contacts the capping layer 5 through the strip-shaped current limiting window 11, thereby injecting current. The front and rear end faces formed by cleaving the epitaxial wafer along a plane perpendicular to the strip direction of the capping layer 5 constitute a front mirror 8 and a rear mirror 9. The light of the laser is emitted from the front mirror 8 and the rear mirror 9 under the ridge-shaped strip capping layer 5 after being generated by the Al x Ga 1-x N material multiple quantum well active light-emitting layer 3.

[0009] Furthermore, in order to limit the current injected into the laser to a strip-shaped area with a smaller area to reduce the threshold, and at the same time, large-area ohmic contact can improve the thermal characteristics of the device. The present invention proposes an AlGaN ultraviolet laser with an inner strip (silicon dioxide isolation inner strip current limiting window) structure and p-NiO as the capping layer (light confinement layer and hole injection layer) (see attached Figure 5 and the attached drawing description). It is successively composed of a substrate 1, an n-type Al 18 / cm 3 ~9.9×10 19 / cm 3 )-doped n-type Al y Ga 1-y N epitaxial lower confinement layer (light, hole confinement layer and electron injection layer) 2, an Al y Ga 1- y N epitaxial lower confinement layer 2, an Al x Ga 1-x N material multiple quantum well active light-emitting layer 3, an Al x Ga 1-x N material multiple quantum well active light-emitting layer 3, an Mg (carrier concentration range of 1×10 17 / cm 3 ~5×10 18 / cm 3 )-doped p-type Al z Ga 1-z N electron confinement layer 4, and a lower electrode 7 prepared under the substrate 1. It is characterized in that: the substrate 1 is an n-type SiC or n-type GaN crystal wafer (carrier concentration range of 1×10 18 / cm 3 ~9.9×10 19 / cm 3 ); On the Al z Ga 1-zA silicon dioxide current isolation layer 10 is prepared on the N electron confinement layer 4. A strip-shaped current confinement window 11 is prepared on the silicon dioxide current isolation layer 10. A cover layer (light confinement layer and hole injection layer) 5 is prepared on the silicon dioxide current isolation layer 10 and the strip-shaped current confinement window 11. The cover layer (light confinement layer and hole injection layer) 5 is p-NiO, and the hole concentration is 1×10 18 / cm 3 ~9.9×10 20 / cm 3 ; The cover layer 5 contacts the Al z Ga 1-z N electron confinement layer 4 through the strip-shaped current confinement window 11, so as to inject current; An upper electrode 6 is prepared on the cover layer 5 to form a large-area ohmic contact; The front and rear end faces cleaved from the epitaxial wafer along the plane perpendicular to the strip direction of the strip-shaped current confinement window 11 constitute a front mirror 8 and a rear mirror 9. The light of the laser is emitted from the front mirror 8 and the rear mirror 9 below the strip-shaped current confinement window 11 after being generated in the Al x Ga 1-x N material multi-quantum well active light-emitting layer 3.

[0010] Fabrication method: For the AlGaN ultraviolet light-emitting diode and laser with p-NiO as the cover layer (light confinement layer and hole injection layer), the GaN buffer layer 12, Al y Ga 1-y N epitaxial lower confinement layer (light, hole confinement layer and electron injection layer) 2, Al x Ga 1-x N material multi-quantum well active light-emitting layer 3 and Al z Ga 1-zThe N-type electron confinement layer 4 can be epitaxially grown by using the currently well-developed conventional MOCVD (Metal-Organic Chemical Vapor Deposition) process. At present, the process for preparing p-NiO thin film materials by the MOCVD method is not yet mature, so the p-NiO cap layer 5 is prepared by magnetron sputtering. The material for preparing the upper electrode 6 can be a single metal or binary alloy material such as Au or Ni-Au, Ti-Au, Zn-Au or Pt-Au, or a ternary alloy and quaternary alloy material such as Ti-Pt-Au, Ti-Ni-Au or Ni-Pt-Au. The preparation method can be thermal evaporation, electron beam evaporation or magnetron sputtering; then the substrate 1 can be thinned to 80-150 microns by using conventional processes such as manual grinding or grinding machine grinding; the material of the lower electrode 7 can also be a single metal or binary alloy material such as Au, Ni, Ni-Au, Ti-Au, Zn-Au or Pt-Au, or a ternary alloy and quaternary alloy material such as Ti-Pt-Au, Ti-Ni-Au or Ni-Pt-Au. The preparation method can be thermal evaporation, electron beam evaporation or magnetron sputtering. Generally, the materials of the upper and lower electrodes are different; for the preparation of the laser: for the preparation of the ridge-shaped cap layer 5, after the epitaxial wafer is prepared, a layer of p-NiO cap layer is first sputtered, then lithography is carried out, masked with photoresist, and the p-NiO cap layer is etched with hot dilute sulfuric acid to form a ridge shape. The ratio of the dilute sulfuric acid is sulfuric acid: water = 20:100 (volume ratio), and it is heated to 60 °C; this etching solution can only etch the p-NiO cap layer 5 and does not etch Al z Ga 1-zN-type electron confinement layer 4; therefore, this etching solution is selected for the preparation of the ridge mesa capping layer 5, rather than using the conventional plasma etching technology. The silicon dioxide current isolation layer 10 can be prepared by conventional techniques such as electron beam evaporation, thermal decomposition deposition of silane, or magnetron sputtering; the preparation of the current confinement window 11 is carried out by conventional photolithography and silicon dioxide etching techniques or by the lift-off technique; finally, the epitaxial chip with the upper and lower electrodes evaporated is cleaved along the (1, 0, 0) or (1, 1, 0) plane of the substrate into bar strips with a width of 100 microns to 2 mm (note that the strip direction of the prepared ridge mesa capping layer 5 or the current confinement window 11 needs to be perpendicular to the cleavage plane direction), and then the bar strips are sawed into die chips with a width of 100 microns to 500 microns, thus preparing a rectangular laser die chip. The front and rear end faces after cleavage of the epitaxial wafer form the front mirror 8 and the rear mirror 9. The device emits light at the front mirror 8 and the rear mirror 9. The width of the bar strip is the cavity length of the laser resonator. The strip direction of the ridge mesa capping layer 5 and the strip-shaped current confinement window 11 is perpendicular to the front and rear end faces of the epitaxial wafer cleavage; after the die chip is prepared, the die chip is flip-chip mounted, that is, the upper electrode 6 is welded to the heat sink or the bracket, and the lower electrode 7 is wire-bonded to another electrode of the bracket, thus fabricating the laser device.

[0011] The preparation method of the AlGaN ultraviolet light-emitting diode and laser with p-NiO as the capping layer (light confinement layer and hole injection layer) according to the present invention is characterized in that: Al y Ga 1-y N epitaxial lower confinement layer 2, Al x Ga 1-x N material multiple quantum well active light-emitting layer 3 and Al z Ga 1-z N electron confinement layer 4 are prepared by the MOCVD method, the p-NiO capping layer 5 is prepared by the magnetron sputtering method, and the upper electrode 6 and the lower electrode 7 are prepared by thermal evaporation, electron beam evaporation or magnetron sputtering methods.

[0012] The effects and benefits of the present invention are:

[0013] The AlGaN ultraviolet light-emitting diode and laser with p-NiO as the capping layer (light confinement layer and hole injection layer) prepared by the present invention utilize the characteristics of p-NiO with high hole concentration, low resistivity, wide bandgap and lower refractive index than the AlGaN material, enabling the device to have a good light confinement layer and hole injection, and can also reduce the series resistance and working voltage of the device, and a new type of ultraviolet light-emitting diode and laser with a shorter wavelength than that using only the AlGaN material system can be obtained; at the same time, the output power of the device is increased, and the application range of the device is expanded. Description of the Drawings

[0014] Figure 1: Schematic diagram of the AlGaN ultraviolet light-emitting diode structure with p-NiO prepared in Example 1 as the cap layer (light confinement layer and hole injection layer).

[0015] Figure 2 : Schematic diagram of the AlGaN ultraviolet light-emitting diode structure with p-NiO prepared in Example 2 as the cap layer (light confinement layer and hole injection layer) and also serving as the electron confinement layer.

[0016] Figure 3 : Schematic diagram of the AlGaN ultraviolet laser structure with p-NiO prepared in Example 3 as the cap layer (light confinement layer and hole injection layer).

[0017] Figure 4 : Schematic diagram of the AlGaN ultraviolet laser structure with a ridge-shaped strip and p-NiO prepared in Example 4 as the cap layer (light confinement layer and hole injection layer).

[0018] Figure 5 : Schematic diagram of the AlGaN ultraviolet laser structure with an inner strip structure and p-NiO as the cap layer prepared in Example 5.

[0019] Figure 6 : Voltage-current characteristic curve of the AlGaN ultraviolet light-emitting diode with p-NiO prepared in Example 1 as the cap layer. It can be seen from the slope of the voltage-current characteristic curve that the series resistance of the device is small, indicating that the resistivity of p-NiO is very low.

[0020] Figure 7 : Electroluminescence spectrum of the AlGaN ultraviolet light-emitting diode with p-NiO prepared in Example 1 as the cap layer. It can be seen that the device has good luminescence characteristics.

[0021] Figure 8 : Electro-injection sputtering spectrum of the AlGaN ultraviolet laser with p-NiO prepared in Example 3 as the cap layer, where Figure 8 (a) in it is the sputtering spectrum at different currents, Figure 8 (b) in it is the sputtering spectrum at a working voltage of 4.5 V and a current of 60 mA. It can be seen that the sputtering peak wavelength is around 360 nm in the ultraviolet band. This indicates the feasibility of this structural device.

[0022] Table 1: Hall test results of NiO thin film samples sputtered at different temperatures in the examples

[0023] Temperature (°C) Resistivity (Ω·cm) <![CDATA[Mobility (cm 2 / v.s)]]> <![CDATA[Carrier concentration ( / cm 3 ).]]> Room temperature 2.818 0.0466 <![CDATA[+9.638×10 20 > 150° 3.629 0.0657 <![CDATA[+9.417×10 19 > 250° 3.853 0.244 <![CDATA[+6.647×10 19 > 350° 4.038 0.594 <![CDATA[+5.153×10 18 >

[0024] The names of each part in the figure are: substrate 1, Al y Ga 1-y N epitaxial lower confinement layer 2, Al x Ga 1-xN material multi - quantum well active light - emitting layer 3, Al z Ga 1-z N electron confinement layer 4, capping layer (light confinement layer and hole injection layer) 5, upper electrode 6, lower electrode 7, front mirror 8, rear mirror 9, silicon dioxide current isolation layer 10, strip - shaped current confinement window 11, buffer layer 12. Specific embodiments

[0025] The specific embodiments and implementation processes of the present invention will be described in detail below in combination with the technical solutions and drawings.

[0026] Embodiment 1

[0027] The AlGaN ultraviolet light - emitting diode with p - NiO as the capping layer (light confinement layer and hole injection layer) is shown in the appendix Figure 1 . Its preparation process is as follows: Using an Al2O3 crystal wafer as the substrate 1. Since the lattice mismatch between the Al2O3 crystal and the GaN crystal prepared at high temperature is relatively large, first, a 20 - nm - thick undoped GaN buffer layer 12 is grown by MOCVD at a low temperature (550 °C). Then, using the conventional MOCVD process, a 2 - micron - thick n - type (doped with Si, carrier concentration of 4×10 18 / cm 3 ) Al y Ga 1-y N epitaxial lower layer 2, an undoped Al x Ga 1-x N material multi - quantum well active light - emitting layer 3 and a p - type (doped with Mg, carrier concentration of 1×10 17 / cm 3 ) Al z Ga 1-z N electron confinement layer 4 are epitaxially grown in sequence on the GaN buffer layer 12; The Al x Ga 1-x N material multi - quantum well active light - emitting layer 3 is composed of well layers Al x1 Ga 1-x1 N and barrier layers Al x2 Ga 1-x2 N alternatingly. The well layer Al x1 Ga 1-x1 N of the quantum well is 3 nm thick, and the value of its Al component x1 can be selected between 0 and 0.7 according to the wavelength of the device to be prepared. The value of the Al component x2 of the quantum well barrier layer Al x2 Ga 1-x2 N is 0.05 - 0.2 larger than the x1 value of the well layer, with a thickness of 5 nm; In our preliminary experiments, the x1 value of the well layer of the quantum well is selected as 0.52 (wavelength of about 275.5 nm), the x2 value of the barrier layer of the quantum well is 0.62, and the number of pairs of the quantum well is initially selected as 3 (it can be 2 - 5 pairs); Al y Ga1-y The Al composition y value of the N epitaxial lower limit layer 2 and Al z Ga 1-z The Al composition z value of the N electron confinement layer 4 both need to be 0.1 - 0.5 greater than the x1 value, Al z Ga 1-z The thickness of the N electron confinement layer 4 is 20 nm; in our preliminary experiment, the y value is selected as 0.62 and the z value is 0.7; the MO sources used in the MOCVD process are: trimethylaluminum (TMAl) as the aluminum source, trimethylgallium (TMGa) as the gallium source, ammonia (NH3) as the nitrogen source, silane (SiH4) as the doped silicon source, and bis(cyclopentadienyl)magnesium (Cp2Mg) as the doped magnesium source. The growth temperature varies slightly according to the Al content. The growth temperature of the Al 0.52 Ga 0.48 N quantum well well layer with an Al content of 0.52 is 1065 °C, and the Al 0.62 Ga 0.38 The growth temperature of the N quantum well barrier layer and the epitaxial lower limit layer 2 is 1072 °C, and the Al 0.7 Ga 0.3 The growth temperature of the N electron confinement layer is 1080 °C; since the doping concentration of the p-NiO cap layer 5 is very high (10 19 / cm 3 ~10 20 / cm 3 ), so the doping concentration of the p-type (Mg-doped) Al z Ga 1-z N electron confinement layer 4 can be a little lower, which is 1×10 17 / cm 3 is okay; after the epitaxial wafer is prepared, a p-NiO cap layer 5 is prepared on the Al z Ga 1-z N electron confinement layer 4 by magnetron sputtering; the target source used for magnetron sputtering the p-NiO cap layer 5 is a ceramic target of NiO plus 2% mass fraction of Li2O. Table 1 shows the Hall test results of the NiO thin film samples sputtered at different temperatures. In our preliminary experiment, the selected temperature is 150 °C and the thickness of the p-NiO cap layer 5 is 200 nm; then, part of the p-NiO cap layer 5, Al z Ga 1-z N electron confinement layer 4 and Al x Ga 1-x N material multiple quantum well active light-emitting layer 3 are removed by conventional plasma etching technology and photolithography, and the Al y Ga 1-y N epitaxial lower limit layer 2 is exposed in this part of the region; then, using the photoresist lift-off technology (Lift of), the Al y Ga 1-yFor a partial area of the N epitaxial lower limit layer 2, Ti / Al / Ni / Au is deposited to prepare the lower electrode 7, with corresponding thicknesses of 20 nm / 120 nm / 50 nm / 100 nm; then, Au is deposited on a partial area of the p-NiO capping layer 5 by using the photoresist masking and stripping technique to prepare the upper electrode 6, with a thickness of about 300 nm; then annealing is carried out under the protection of inert gas alloy, with an annealing temperature of 450 °C and a time of 3 minutes, and finally dicing is performed to form die chips.

[0028] Figure 6 : is the voltage-current characteristic curve of the AlGaN ultraviolet light-emitting diode with p-NiO as the capping layer described in this embodiment. Figure 7 : is the electroluminescence spectrum of the AlGaN ultraviolet light-emitting diode with p-NiO as the capping layer described in the embodiment.

[0029] Example 2

[0030] For the AlGaN ultraviolet light-emitting diode with p-NiO as the capping layer (light confinement layer and hole injection layer) and also serving as the electron confinement layer, see the appendix Figure 2 . The preparation process is as follows: an Al2O3 crystal wafer is used as the substrate 1. Since the lattice mismatch between the Al2O3 crystal and the GaN crystal prepared at high temperature is relatively large, first, a 20-nm-thick undoped GaN buffer layer 12 is grown by MOCVD at a low temperature (550 °C), and then a 2-μm-thick n-type (doped with Si, carrier concentration of 4×10 18 / cm 3 ) Al y Ga 1-y N epitaxial lower limit layer 2 and an undoped Al x Ga 1-x N material multi-quantum well active light-emitting layer 3 are sequentially epitaxially grown on the GaN buffer layer 12 by using the conventional MOCVD process; the Al x Ga 1-x N material multi-quantum well active light-emitting layer 3 is composed of well layers Al x1 Ga 1-x1 N and barrier layers Al x2 Ga 1-x2 N alternatingly formed. The quantum well well layer Al x1 Ga 1-x1 N has a thickness of 3 nm, and its Al component x1 value can be selected between 0 and 0.7 according to the wavelength of the device to be prepared. The Al component x2 value of the quantum well barrier layer Al x2 Ga 1-x2 N is 0.05 - 0.2 larger than the x1 value of the well layer and has a thickness of 5 nm; we initially selected the x1 value to be 0.52 (wavelength of about 275.5 nm) and the x2 value to be 0.62; Al y Ga 1-yThe Al composition y value of the N epitaxial lower limit layer 2 is 0.1 - 0.5 greater than the x1 value; in our preliminary experiment, the y value is selected to be 0.62; the MO sources used in the MOCVD process are: trimethylaluminum (TMAl) as the aluminum source, trimethylgallium (TMGa) as the gallium source, ammonia (NH3) as the nitrogen source, and silane (SiH4) as the doped silicon source. The growth temperature varies slightly according to the Al content. For Al with an Al content of 0.52 0.52 Ga 0.48 The growth temperature of the N quantum well well layer is 1065 °C. For Al with an Al content of 0.62 0.62 Ga 0.38 The growth temperature of the N quantum well barrier layer and the epitaxial lower limit layer 2 is 1072 °C; after the epitaxial wafer is prepared, a p-NiO cap layer 5 is prepared on the Al x Ga 1-x N quantum well active layer light-emitting layer 3 by magnetron sputtering. The target source used for magnetron sputtering the p-NiO cap layer 5 is a ceramic target of NiO plus 2% by mass fraction of Li2O. Table 1 shows the Hall test results of NiO thin film samples sputtered at different temperatures. In our preliminary experiment, the temperature is selected to be 150 °C, and the thickness of the p-NiO cap layer 5 is 200 nm; then, using conventional plasma etching technology, photolithography is used to etch away part of the p-NiO cap layer 5, Al x Ga 1-x N material multi-quantum well active light-emitting layer 3, and in this part of the region, Al y Ga 1-y N epitaxial lower limit layer 2 is exposed; then, using the photoresist masking and lift-off technology (Lift of), Ti / Al / Ni / Au is evaporated on the exposed part of the Al y Ga 1-y N epitaxial lower limit layer 2 to prepare the lower electrode 7, with corresponding thicknesses of 20 nm / 120 nm / 50 nm / 100 nm; then, using the photoresist masking and lift-off technology again, Au is evaporated on part of the p-NiO cap layer 5 to prepare the upper electrode 6, with a thickness of about 300 nanometers; then, annealing is carried out under inert gas protection alloy, with an annealing temperature of 450 °C and a time of 3 minutes, and finally, dicing is performed to make die chips.

[0031] Example 3

[0032] The AlGaN ultraviolet laser with p-NiO as the cap layer (light confinement layer and hole injection layer) is shown in the appendix Figure 3 . The preparation process is as follows: an n-type GaN crystal wafer (carrier concentration 5×10 18 / cm 3 ) is used as the substrate, and a 2-micron n-type (doped with Si, carrier concentration 4×10 18 / cm 3 ) Aly Ga 1-y N epitaxial lower limit layer 2, undoped Al x Ga 1-x N material multi - quantum well active light - emitting layer 3 and p - type (doped with Mg, carrier concentration is 1×10 17 / cm 3 ) Al z Ga 1-z N electron confinement layer 4; After the epitaxial wafer is prepared, a p - NiO capping layer 5 is prepared on the Al z Ga 1-z N electron confinement layer 4 by magnetron sputtering; The Al x Ga 1-x N material multi - quantum well active light - emitting layer 3 is composed of well layers Al x1 Ga 1-x1 N and barrier layers Al x2 Ga 1-x2 N alternatingly. The quantum well layer Al x1 Ga 1-x1 N is 3 nm thick, and its Al component x1 value can be selected between 0 and 0.7 according to the wavelength of the device to be prepared. The Al component x2 value of the quantum well barrier layer Al x2 Ga 1-x2 N is 0.05 - 0.2 larger than the x1 value of the well layer and has a thickness of 5 nm; In our preliminary experiment, the x1 value is selected as 0 (wavelength is about 360 nm) and the x2 value is 0.07; The Al component y value of the Al y Ga 1-y N epitaxial lower limit layer 2 and the Al component z value of the Al z Ga 1-z N electron confinement layer 4 both need to be 0.1 - 0.5 larger than the x1 value. The Al z Ga 1-z N electron confinement layer 4 has a thickness of 20 nm; In our preliminary experiment, the y value and z value are selected as 0.2. The doping concentration of the Al y Ga 1-y N epitaxial lower limit layer 2 is 4×10 18 / cm 3 ; The MOCVD process epitaxially grows an n - type (doped with Si) Al y Ga 1-y N epitaxial lower limit layer 2, undoped Al x Ga 1- x N material multi - quantum well active light - emitting layer 3 and p - type (doped with Mg) Al z Ga 1-zThe MO sources used for the N electron confinement layer 4 are as follows: trimethylaluminum (TMAl) is used as the aluminum source, trimethylgallium (TMGa) is used as the gallium source, ammonia (NH3) is used as the nitrogen source, silane (SiH4) is used as the doped silicon source, and bis(cyclopentadienyl)magnesium (Cp2Mg) is used as the doped magnesium source. The growth temperature varies slightly according to the Al content. The growth temperature of GaN with zero Al content is 1030 °C, and for Al with an Al content of 0.07 0.07 Ga 0.93 The growth temperature of the Al 0.93 Ga 0.2 N quantum well barrier layer is 1035 °C, and for Al with an Al content of 0.2 0.2 Ga 0.8 The growth temperature of the epitaxial lower layer 2 and the electron confinement layer 4 of Al 0.8 N is 1044 °C; due to the very high doping concentration of the p-NiO cap layer 5 (10 19 / cm 3 ), the doping concentration of the p-type (Mg-doped) Al z Ga 1-z N electron confinement layer 4 can be a little lower, which is 1×10 z Ga 1-z / cm 17 / cm 3 is sufficient; the target source used for magnetron sputtering the p-NiO cap layer 5 is a ceramic target of NiO plus 2% by mass fraction of Li2O. Table 1 shows the Hall test results of NiO thin film samples sputtered at different temperatures. We initially selected a temperature of 150 °C and the thickness of the p-NiO cap layer 5 is 200 nm; then a metal is evaporated using a thermal evaporation platform or an electron beam evaporation platform to prepare the upper electrode 6 on the p-NiO cap layer 5; then, the substrate is thinned to 90 microns, and a metal lower electrode 7 is evaporated on the substrate surface, and then alloy annealing is carried out under the protection of inert gas. The annealing temperature is 450 °C and the time is 3 minutes; finally, the epitaxial chip with the upper and lower electrodes evaporated is cleaved along the (1, 0, 0) or (1, 1, 0) plane of the substrate 1 into bar strips with a width of 1000 microns, and then the bar strips are sawn into die chips with a width of 300 microns, thus preparing a rectangular laser die. The front and rear end faces of the cleaved epitaxial wafer form the front mirror 8 and the rear mirror 9. The device emits light from the front mirror 8 and the rear mirror 9. The original bar strip width is the cavity length of the laser resonator; the material of the upper electrode 6 is Au, and its thickness is about 300 nm. The material of the lower electrode 7 is Ti / Al / Ni / Au, and the corresponding thicknesses are 20 nm / 120 nm / 50 nm / 100 nm.

[0033] In the initial stage of implementing this embodiment, in order to test the hole injection effect of the p-NiO cap layer on the Al x Ga 1-x N active region, a simplified device structure was prepared. The x1 value of this structure was selected as 0, and a simple p-n junction composed of a p-NiO cap layer and an n-GaN active layer was prepared. This p-n junction has good diode characteristics and realizes random scattering sputtering, Figure 8 ​​​​Sputtering spectrogram for diode electrical injection. From Figure 8 it can be seen that the sputtering peak wavelengths are all around 360 nm in the ultraviolet band. Such a simple p-n junction can generate electrical injection sputtering, indicating that the hole injection rate of the p-NiO capping layer is very high.

[0034] Example 4

[0035] An AlGaN ultraviolet laser with a ridge-shaped p-NiO as the capping layer (optical confinement layer and hole injection layer) is shown in the appendix Figure 4 . The preparation process is as follows: an n-type GaN wafer (carrier concentration 5×10 18 / cm 3 ) is used as the substrate, and a 2-μm-thick n-type (doped with Si, carrier concentration 4×10 18 / cm 3 ) Al y Ga 1-y N epitaxial lower layer 2, an undoped Al x Ga 1-x N material multi-quantum well active light-emitting layer 3, and a p-type (doped with Mg, carrier concentration 1×10 17 / cm 3 ) Al z Ga 1-z N electron confinement layer 4 are grown on the GaN wafer substrate by the currently mature conventional MOCVD process; the Al x Ga 1-x N material multi-quantum well active light-emitting layer 3 is composed of alternating well layers of Al x1 Ga 1-x1 N and barrier layers of Al x2 Ga 1-x2 . The well layer Al x1 Ga 1-x1 N is 3 nm thick, and its Al component x1 value can be selected between 0 and 0.7 according to the wavelength of the device to be prepared. The Al component x2 value of the quantum well barrier layer Al x2 Ga 1-x2 N can be 0.05 - 0.2 larger than the x1 value of the well layer, and the thickness is 5 nm; in our preliminary experiments, the x1 value is selected as 0 (wavelength around 360 nm) and the x2 value is selected as 0.07; the Al component y value of the Al y Ga 1-y N epitaxial lower layer 2 and the Al component z value of the Al z Ga 1-z N electron confinement layer 4 both need to be 0.1 - 0.5 larger than the x1 value. Al z Ga 1-zThe thickness of the N electron confinement layer 4 is 20 nm. We initially selected the y value and z value to be 0.2 in the preliminary experiment. The MO source for epitaxial growth, the growth temperature, the carrier concentration, etc. are the same as in Example 3. After the epitaxial wafer is prepared, a p-NiO cap layer 5 is prepared on the Al z Ga 1-z N electron confinement layer 4 by magnetron sputtering. The target source for magnetron sputtering the p-NiO cap layer 5 is a ceramic target of NiO plus 2% Li2O, the temperature is 150 °C, and the thickness of the p-NiO is 200 nm. Then, photolithography is performed, masked with photoresist, and the p-NiO cap layer is etched with hot dilute sulfuric acid to form a ridge-shaped strip. The ratio of the dilute sulfuric acid is sulfuric acid: water = 20:100 (volume ratio), heated to 60 °C, and the Al z Ga 1-z N electron confinement layer 4 is exposed outside the ridge-shaped strip p-NiO cap layer 5. The width of the ridge-shaped strip p-NiO cap layer 5 is 10 microns. Then, the photoresist is retained, and a silicon dioxide current isolation layer 10 (with a thickness of 200 nm) is prepared on the ridge-shaped strip cap layer 5 and the exposed Al z Ga 1-z N electron confinement layer 4 by electron beam evaporation. Then, the photoresist is removed, and the silicon dioxide layer on the photoresist is stripped off accordingly, thereby forming a strip-shaped current confinement window 11 with a width of about 10 microns. Then, an upper electrode 6 is prepared by evaporating metal on the silicon dioxide current isolation layer 10 and the strip-shaped current confinement window 11. The upper electrode 6 contacts the cap layer 5 through the strip-shaped current confinement window 11 for current injection. Then, the substrate is thinned to 90 microns, and a metal lower electrode 7 is evaporated on the substrate surface. Then, alloy annealing is performed under inert gas protection, the annealing temperature is 450 °C, and the time is 3 minutes. Finally, the epitaxial chip with the upper and lower electrodes evaporated is cleaved along the (1, 0, 0) or (1, 1, 0) plane of the substrate into bars with a width of 1000 microns (note that the prepared ridge-shaped strip cap layer 5 needs to be perpendicular to the cleavage plane direction). Then, the bars are sawn into die chips with a width of 300 microns, thus preparing a rectangular laser die. The front and rear end faces of the epitaxial wafer cleavage form a front mirror 8 and a rear mirror 9. The device emits light from the front mirror 8 and the rear mirror 9 under the ridge-shaped strip. The original bar width is the cavity length of the laser resonator. The strip directions of the ridge-shaped strip p-NiO cap layer 5 and the strip-shaped current confinement window 11 are perpendicular to the front and rear end faces of the epitaxial wafer cleavage. The material of the upper electrode 6 is Au, and its thickness is about 300 nm. The material of the lower electrode 7 is Ti / Al / Ni / Au, with corresponding thicknesses of 20 nm / 120 nm / 50 nm / 100 nm.

[0036] Example 5

[0037] An AlGaN ultraviolet laser with a ridge-shaped strip structure and a p-NiO cap layer is shown in the appendix Figure 5. The preparation process is as follows: an n-type GaN crystal wafer (carrier concentration 5×10 18 / cm 3 ) is used as the substrate, and a 2-μm-thick n-type (doped with Si, carrier concentration 4×10 18 / cm 3 ) Al y Ga 1-y N epitaxial lower limit layer 2, an undoped Al x Ga 1-x N material multi-quantum well active light-emitting layer 3 and a p-type (doped with Mg, carrier concentration 1×10 17 / cm 3 ) Al z Ga 1-z N electron confinement layer 4 are epitaxially grown on the GaN crystal wafer substrate by the currently mature conventional MOCVD process; the Al x Ga 1-x N material multi-quantum well active light-emitting layer 3 is composed of alternating well layers of Al x1 Ga 1-x1 N and barrier layers of Al x2 Ga 1-x2 N. The well layer of Al x1 Ga 1-x1 N is 3 nm thick, and the value of its Al component x1 can be selected between 0 and 0.7 according to the wavelength of the device to be prepared. The value of the Al component x2 of the quantum well barrier layer of Al x2 Ga 1-x2 N can be 0.05 - 0.2 larger than the x1 value of the well layer, and the thickness is 5 nm; in our preliminary experiments, the x1 value is selected to be 0 (wavelength around 360 nm) and the x2 value is 0.07; the value of the Al component y of the Al y Ga 1-y N epitaxial lower limit layer 2 and the value of the Al component z of the Al z Ga 1- z N electron confinement layer 4 both need to be 0.1 - 0.5 larger than the x1 value. Al z Ga 1-zThe thickness of the N-type electron confinement layer 4 is 20 nm; in our preliminary experiments, the values of y and z are selected to be 0.2; the MO source for epitaxial growth, the growth temperature, the carrier concentration, etc. are the same as in Example 3; then, a silicon dioxide current isolation layer 10 (with a thickness of 200 nm) is prepared on the electron confinement layer 4 by electron beam evaporation, and a strip-shaped current confinement window 11 with a width of about 3 microns is lithographically etched on the silicon dioxide current isolation layer 10 using a conventional lithography and etching process. Then, a p-NiO capping layer 5 is prepared on the silicon dioxide current isolation layer 10 and the strip-shaped current confinement window 11 by magnetron sputtering at a temperature of 150°C and a thickness of 200 nm (the target source used is the same as in Example 3); then, an upper electrode 6 is deposited on the p-NiO capping layer 5 by evaporation; the substrate is thinned to 90 microns, and then a metal lower electrode 7 is deposited on the substrate surface. Then, alloy annealing is carried out under the protection of inert gas at an annealing temperature of 450°C for 3 minutes; finally, the epitaxial chip with the upper and lower electrodes deposited is cleaved along the (1, 0, 0) or (1, 1, 0) plane of the substrate into bars with a width of 1000 microns (note that the prepared current confinement window 11 needs to be perpendicular to the direction of this cleavage plane), and then the bars are sawed into die chips with a width of 300 microns, thus preparing a rectangular laser die. The front and rear end faces of the epitaxial wafer cleavage form the front mirror 8 and the rear mirror 9. The device emits light from the front mirror 8 and the rear mirror 9 below the strip-shaped current confinement window 11. The original bar width is the cavity length of the laser resonator, and the strip direction of the strip-shaped current confinement window 11 is perpendicular to the front and rear end faces of the epitaxial wafer cleavage; the material of the upper electrode 6 is Au, and its thickness is about 300 nm, and the material of the lower electrode 7 is Ti / Al / Ni / Au, with corresponding thicknesses of 20 nm / 120 nm / 50 nm / 100 nm.

Claims

1. An AlGaN ultraviolet light-emitting diode with a p-NiO capping layer, which is successively composed of a substrate (1), a GaN buffer layer (12) prepared on the substrate (1), an n-type Si-doped Al y Ga 1-y N epitaxial lower confinement layer (2), an Al y Ga 1-y N epitaxial lower confinement layer (2) on which are prepared discrete Al x Ga 1-x N material multiple quantum well active light-emitting layer (3) and a lower electrode (7), an Al x Ga 1-x N material multiple quantum well active light-emitting layer (3) on which is prepared a p-type Mg-doped Al z Ga 1-z N electron confinement layer (4), an Al z Ga 1-z N electron confinement layer (4) on which is prepared a capping layer (5), and an upper electrode (6) prepared on the capping layer (5). It is characterized in that: The substrate (1) is an Al2O3 or Si crystal wafer; the capping layer (5) is p-NiO with a hole concentration of 1×10 18 / cm 3 ~9.9×10 20 / cm 3 ; The Al x Ga 1-x N material multi-quantum well active light-emitting layer (3) is composed of alternating well layers of Al x1 Ga 1-x1 N and barrier layers of Al x2 Ga 1-x2 N, where x1 is selected between 0 and 0.7, the value of x2 is 0.05 - 0.2 greater than the value of x1, and the values of y and z are both 0.1 - 0.5 greater than the value of x1.

2. An AlGaN ultraviolet light-emitting diode with p-NiO as a cap layer and also serving as an electron confinement layer, which is successively composed of a substrate (1), a GaN buffer layer (12) prepared on the substrate (1), an n-type Si-doped Al y Ga 1-y N epitaxial lower confinement layer (2), an Al y Ga 1-y N epitaxial lower confinement layer (2) with mutually discrete Al x Ga 1-x N material multiple quantum well active light-emitting layer (3) and a lower electrode (7), an Al x Ga 1-x N material multiple quantum well active light-emitting layer (3) with a cap layer (5) prepared thereon, and an upper electrode (6) prepared on the cap layer (5), and is characterized in that: The substrate (1) is an Al2O3 or Si crystal wafer; the cover layer (5) is p-NiO with a hole concentration of 1×10 18 / cm 3 ~9.9×10 20 / cm 3 ; The Al x Ga 1-x N material multi-quantum well active light-emitting layer (3) is composed of well layers of Al x1 Ga 1-x1 N and barrier layers of Al x2 Ga 1-x2 N alternatingly, the value of x1 is selected between 0 and 0.7, the value of x2 is 0.05 to 0.2 greater than the value of x1, and the value of y is 0.1 to 0.5 greater than the value of x1.

3. An AlGaN ultraviolet laser with a p-NiO capping layer, which is successively composed of a substrate (1), an n-type Al doped with Si prepared on the substrate (1) y Ga 1-y N epitaxial lower confinement layer (2), Al y Ga 1-y Al prepared on the N epitaxial lower confinement layer (2) x Ga 1-x N material multiple quantum well active light-emitting layer (3), Al x Ga 1-x A p-type Al doped with Mg prepared on the N material multiple quantum well active light-emitting layer (3) z Ga 1-z N electron confinement layer (4), Al z Ga 1-z A capping layer (5) prepared on the N electron confinement layer (4), an upper electrode (6) prepared on the capping layer (5), and a lower electrode (7) prepared under the substrate 1. It is characterized in that: The substrate (1) is an n-type SiC or n-type GaN crystal wafer, with a carrier concentration range of 1×10 18 / cm 3 ~9.9×10 19 / cm 3 ; the cap layer (5) is p-NiO, with a hole concentration of 1×10 18 / cm 3 ~9.9×10 20 / cm 3 ; the Al x Ga 1-x N material multiple quantum well active light-emitting layer (3) is composed of well layers Al x1 Ga 1-x1 N and barrier layers Al x2 Ga 1-x2 N alternatingly. The value of x1 is selected between 0 and 0.7, the value of x2 is 0.05 - 0.2 larger than the value of x1, and the values of y and z are both 0.1 - 0.5 larger than the value of x1; the front and rear end faces cleaved from the epitaxial wafer form the front mirror (8) and the rear mirror (9). The light of the laser is emitted from the front mirror (8) and the rear mirror (9) under the cap layer (5) after being generated in the Al x Ga 1-x N material multiple quantum well active light-emitting layer (3).

4. An AlGaN ultraviolet light laser with a ridge-shaped strip structure and a p-NiO capping layer, which consists of a substrate (1), an n-type Al doped with Si prepared on the substrate (1), y Ga 1-y N epitaxial lower confinement layer (2), an Al y Ga 1-y N epitaxial lower confinement layer (2), an Al x Ga 1-x N material multiple quantum well active light-emitting layer (3), an Al x Ga 1-x N material multiple quantum well active light-emitting layer (3), a p-type Al doped with Mg prepared on the Al z Ga 1-z N electron confinement layer (4), and a lower electrode (7) prepared under the substrate (1), and is characterized in that: The substrate (1) is an n-type SiC or n-type GaN crystal wafer with a carrier concentration range of 1×10 18 / cm 3 ~9.9×10 19 / cm 3 ; A cap layer (5) with a ridge-shaped strip structure is fabricated on the Al z Ga 1-z N electron confinement layer (4). The cap layer (5) is p-NiO with a hole concentration of 1×10 18 / cm 3 ~9.9×10 20 / cm 3 ; The Al x Ga 1-x N material multiple quantum well active light-emitting layer (3) is composed of well layers Al x1 Ga 1-x1 N and barrier layers Al x2 Ga 1-x2 N alternatingly. The value of x1 is selected between 0 and 0.7, the value of x2 is 0.05 - 0.2 greater than the value of x1, and the values of y and z are both 0.1 - 0.5 greater than the value of x1; A silicon dioxide current isolation layer (10) is fabricated on the cap layer (5). A strip-shaped current confinement window (11) is fabricated on the silicon dioxide current isolation layer (10) at the top of the ridge-shaped strip cap layer (5). An upper electrode (6) is fabricated on the silicon dioxide current isolation layer (10) and the strip-shaped current confinement window (11). The upper electrode (6) contacts the cap layer (5) through the strip-shaped current confinement window (11) for current injection; The front and rear end faces cleaved from the epitaxial wafer along the plane perpendicular to the strip direction of the cap layer (5) form a front mirror (8) and a rear mirror (9). The light of the laser is emitted from the front mirror (8) and the rear mirror (9) under the ridge-shaped strip cap layer (5) after being generated in the Al x Ga 1-x N material multiple quantum well active light-emitting layer (3).

5. An AlGaN ultraviolet laser with a p-NiO capping layer of an inner strip structure, which is successively composed of a substrate (1), an n-type Al doped with Si prepared on the substrate (1) y Ga 1-y N epitaxial lower confinement layer (2), an Al y Ga 1-y N epitaxial lower confinement layer (2), an Al x Ga 1-x N material multiple quantum well active light-emitting layer (3), an Al x Ga 1-x N material multiple quantum well active light-emitting layer (3), a p-type Al doped with Mg prepared on the layer z Ga 1-z N electron confinement layer (4), a lower electrode (7) prepared under the substrate (1), and is characterized in that: The substrate (1) is an n-type SiC or n-type GaN crystal wafer, with a carrier concentration range of 1×10 18 / cm 3 ~9.9×10 19 / cm 3 ; The Al x Ga 1- x N material multiple quantum well active light-emitting layer (3) is composed of well layers Al x1 Ga 1-x1 N and barrier layers Al x2 Ga 1-x2 N alternatingly. The value of x1 is selected between 0 and 0.7, the value of x2 is 0.05 - 0.2 greater than the value of x1, and the values of y and z are both 0.1 - 0.5 greater than the value of x1; On the Al z Ga 1-z N electron confinement layer (4), a silicon dioxide current isolation layer (10) is prepared. On the silicon dioxide current isolation layer (10), a strip-shaped current confinement window (11) is prepared. On the silicon dioxide current isolation layer (10) and the strip-shaped current confinement window (11), a cover layer (5) is prepared. The cover layer (5) is p-NiO, with a hole concentration of 1×10 18 / cm 3 ~9.9×10 20 / cm 3 ; The cover layer (5) contacts the Al z Ga 1-z N electron confinement layer (4) through the strip-shaped current confinement window (11) for current injection; On the cover layer (5), an upper electrode (6) is prepared to form a large-area ohmic contact; The front and rear end faces cleaved from the epitaxial wafer along the plane perpendicular to the strip direction of the strip-shaped current confinement window (11) constitute the front mirror (8) and the rear mirror (9). The light of the laser is emitted from the front mirror (8) and the rear mirror (9) below the strip-shaped current confinement window (11) after being generated in the Al x Ga 1-x N material multiple quantum well active light-emitting layer (3).

6. The preparation method of an AlGaN ultraviolet light-emitting diode with p-NiO as a cap layer according to claim 1, characterized in that: Al y Ga 1-y The confinement layer (2) under the Al x Ga 1-x N multi-quantum well active light-emitting layer (3) and the Al z Ga 1-z N electron confinement layer (4) are prepared by the MOCVD method, the p-NiO capping layer (5) is prepared by the magnetron sputtering method, and the upper electrode (6) and the lower electrode (7) are prepared by thermal evaporation, electron beam evaporation or magnetron sputtering methods.

7. The preparation method of an AlGaN ultraviolet light-emitting diode with p-NiO as a capping layer and also serving as an electron confinement layer according to claim 2, characterized in that: Al y Ga 1-y The confinement layer (2) under the Al x Ga 1-x N material multi-quantum well active light-emitting layer (3) is prepared by the MOCVD method, the p-NiO capping layer (5) is prepared by the magnetron sputtering method, and the upper electrode (6) and the lower electrode (7) are prepared by the thermal evaporation, electron beam evaporation or magnetron sputtering method.

8. The preparation method of an AlGaN ultraviolet laser with p-NiO as the cap layer according to claim 3, characterized in that: Al y Ga 1-y The confinement layer (2) under the Al x Ga 1-x N multi-quantum well active light-emitting layer (3) and the Al z Ga 1-z N electron confinement layer (4) are prepared by the MOCVD method, the p-NiO capping layer (5) is prepared by the magnetron sputtering method, and the upper electrode (6) and the lower electrode (7) are prepared by thermal evaporation, electron beam evaporation or magnetron sputtering methods.

9. The preparation method of an AlGaN ultraviolet laser with a p-NiO of a ridge table strip structure as the cap layer according to claim 4, characterized in that: Al y Ga 1-y The confinement layer (2) under the Al x Ga 1-x N multi-quantum well active light-emitting layer (3) and the Al z Ga 1-z N electron confinement layer (4) are prepared by the MOCVD method; the p-NiO capping layer (5) is prepared by the magnetron sputtering method, and the p-NiO capping layer (5) is etched with hot dilute sulfuric acid to form a mesa stripe structure; the upper electrode (6) and the lower electrode (7) are prepared by thermal evaporation, electron beam evaporation or magnetron sputtering methods.

10. A method for preparing an AlGaN ultraviolet laser with a p-NiO with an inner strip structure as a cap layer, characterized in that: Al y Ga 1-y The confinement layer (2) under the Al x Ga 1-x N multi-quantum well active light-emitting layer (3) and the Al z Ga 1-z N electron confinement layer (4) are prepared by the MOCVD method, the p-NiO capping layer (5) is prepared by the magnetron sputtering method, and the upper electrode (6) and the lower electrode (7) are prepared by thermal evaporation, electron beam evaporation or magnetron sputtering methods.

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