An InN infrared light-emitting diode and laser with p-NiO as the cap layer in the optical communication band and a preparation method thereof

Abstract

An InN infrared light-emitting diode and laser with a p-NiO cap layer in the optical communication band 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 n-type Si-doped GaN epitaxial lower confinement layer, an InN material active light-emitting layer, a p-type Mg-doped GaN electron confinement layer, a p-NiO cap layer, an upper electrode and a lower electrode. The present invention utilizes the characteristics that InN material is a narrow direct bandgap material, suitable for preparing LEDs and LDs around 1.55 µm in the near infrared for the fiber optic communication field. At the same time, by using the characteristics of p-NiO such as high hole concentration, low resistivity, wide bandgap, lower refractive index than GaN material, and very low growth temperature, it can enable good hole injection in the device, as well as good optical confinement and carrier confinement, and prepare a new type of infrared light-emitting tube and laser with good temperature characteristics in the optical communication band, which can expand the application range of the device.

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 InN infrared light-emitting diode and laser in the optical communication band with p-NiO as the cap layer and a method for preparing the same. Background Art

[0002] At present, mankind has entered a highly information-based society, and the social demand for information volume has increased explosively. Photons have become an important carrier of information. Optical fiber communication is an important means of information transmission. Quartz optical fiber has extremely low loss in the wavelength range of about 1.55 µm, and this wavelength band is an ideal band for optical fiber communication systems. Currently, semiconductor light-emitting diodes (LEDs) and lasers (LDs) prepared from InGaAsP / InP material systems are used as light sources in this wavelength band. However, the temperature characteristics of semiconductor light-emitting devices based on InGaAsP / InP material systems are not good, the wavelength varies greatly with temperature, and they cannot operate at higher temperatures. People have to add a semiconductor cooler, a thermistor, and a temperature control circuit to the light-emitting component of such light-emitting devices, which greatly limits the application range of such devices.

[0003] In recent years, it has been found that Ga(In)N-based material light-emitting devices have good temperature characteristics. The bandgap of InN material is only about 0.77 eV, which is a narrow direct bandgap material and is very suitable for preparing pollution-free and high-performance near-infrared LEDs (light-emitting diodes) and LDs (laser tubes) around 1.55 µm for use in the field of optical fiber communication, which is very likely to bring new breakthroughs to the development of optical communication. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above difficulties of InGaAsP / InP material-based light-emitting diodes and lasers. By using the characteristic that the bandgap of InN material is only about 0.77 eV, which is a narrow direct bandgap material and is very suitable for preparing near-infrared LEDs (light-emitting diodes) and LDs (laser tubes) around 1.55 µm for use in the field of optical fiber communication, and at the same time using the characteristics of p-NiO such as wide bandgap, high hole concentration, low refractive index, and low growth temperature, an InN infrared light-emitting diode and laser in the optical communication band with p-NiO as the cap layer (optical confinement layer and hole injection layer) and a method for preparing the same are provided. 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 active light-emitting layer of InN material, and infrared light-emitting diodes and laser devices with good characteristics can be prepared.

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

[0006] The InN infrared light-emitting diode in the optical communication band with p-NiO as the capping layer (optical confinement layer and hole injection layer) designed by the present invention (see (a) in the attached drawing and the description of the attached drawing) is composed of, from bottom to top, a substrate 1, a GaN buffer layer 12 prepared on the substrate 1, an n-type Si-doped GaN epitaxial lower confinement layer (optical, hole confinement layer and electron injection layer) 2 with a Si doping concentration range of 1.0×10 Figure 1 / cm 18 / cm 3 ~9.9×10 19 / cm 3 ), a mutually separated undoped InN material active light-emitting layer 3 and a lower electrode 7 prepared on the GaN epitaxial lower confinement layer 2, a p-type Mg-doped (Mg doping concentration range of 1.0×10 17 / cm 3 ~5.0×10 18 / cm 3 ), a GaN electron confinement layer 4 prepared on the GaN electron confinement layer 4, a capping layer (optical confinement layer and hole injection layer) 5 prepared on the GaN electron confinement layer 4, 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 (optical confinement layer and hole injection layer) 5 is p-NiO with a hole concentration of 1.0×10 18 / cm 3 ~9.9×10 20 / cm 3 ; for the convenience of fiber coupling, the upper electrode 6 is prepared into an outer square and inner circular ring-shaped structure (see (b) in the attached drawing and the description of the attached drawing), and the light is emitted from the inner circle of the upper electrode 6 after being generated in the active light-emitting layer 3. Figure 1 In the optical communication band InN infrared light laser designed by the present invention (see the attached drawing and the description of the attached drawing), which is composed of, from bottom to top, a substrate 1, an n-type Si-doped (doping concentration range of 1.0×10

[0007] / cm Figure 2 ~9.9×10 18 / cm 3 ~9.9×10 19 / cm 3 ), a GaN epitaxial lower confinement layer (optical, hole confinement layer and electron injection layer) 2 prepared on the substrate 1, an undoped InN material active light-emitting layer 3 prepared on the GaN epitaxial lower confinement layer 2, a p-type Mg-doped (doping concentration range of 1.0×10 17 / cm 3~5.0×10 18 / cm 3 ), the GaN electron confinement layer 4, the capping layer (light confinement layer and hole injection layer) 5 prepared on the GaN electron confinement layer 4, and the upper electrode 6 prepared on the capping layer 5. A lower electrode 7 is prepared under the substrate 1. It is characterized in that: the substrate 1 is an n-type SiC or n-type GaN crystal wafer, and its doping concentration range is 1×10 18 / cm 3 ~9.9×10 19 / cm 3 ; the capping layer (light confinement layer and hole injection layer) 5 is p-NiO, and the hole concentration is 1.0×10 18 / cm 3 ~9.9×10 20 / cm 3 ; the front and rear end faces cleaved from the above-mentioned epitaxial wafer form a front mirror 8 and a rear mirror 9. After the light of the laser is generated in the active light-emitting layer 3, it exits through the front mirror 8 and the rear mirror 9 under the capping layer 5.

[0008] Furthermore, in order to limit the current injected into the laser to a strip region with a smaller area to reduce the threshold. The present invention proposes an InN infrared light laser in the optical communication band with a ridge strip structure using p-NiO as the capping layer (light confinement layer and hole injection layer) (see attached Figure 3 and the attached drawings). From bottom to top, it consists of a substrate 1, an n-type Si-doped GaN epitaxial lower confinement layer (light, hole confinement layer and electron injection layer) 2 prepared on the substrate 1 (the doping concentration range is 1.0×10 18 / cm 3 ~9.9×10 19 / cm 3 ), an undoped InN material active light-emitting layer 3 prepared on the GaN epitaxial lower confinement layer 2, a p-type Mg-doped GaN electron confinement layer 4 prepared on the InN material active light-emitting layer 3 (the doping concentration range is 1.0×10 17 / cm 3 ~5.0×10 18 / cm 3 ), and a lower electrode 7 is prepared under the substrate 1. It is characterized in that: the substrate 1 is an n-type SiC or n-type GaN crystal wafer, and its doping concentration range is 1×10 18 / cm 3 ~9.9×10 19 / cm 3 ; a ridge strip structure capping layer (light confinement layer and hole injection layer) 5 is prepared on the GaN electron confinement layer 4. The capping layer (light confinement layer and hole injection layer) 5 is p-NiO, and the hole concentration is 1.0×10 18 / cm3 ~9.9×10 20 / cm 3 ; A silicon dioxide current isolation layer 10 is prepared on the capping layer 5 and the GaN electron confinement layer 4. A strip-shaped current confinement window 11 is prepared on the silicon dioxide current isolation layer 10 at the top of the ridge-shaped strip capping layer 5 (i.e., all of the silicon dioxide current isolation layer 10 at the top of the ridge-shaped strip capping layer 5 is peeled off). An upper electrode 6 is prepared on the silicon dioxide current isolation layer 10 and the strip-shaped current confinement window 11. The upper electrode 6 contacts the capping layer 5 through the strip-shaped current confinement window 11, thereby injecting current. The front and rear end faces cleaved from the above epitaxial wafer along a plane perpendicular to the strip direction of the ridge-shaped strip capping 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 capping layer 5 after being generated in the active light-emitting layer 3.

[0009] Furthermore, in order to confine the current injected into the laser in 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 and reduce the series resistance. The present invention proposes an InN infrared light laser with an inner strip (silicon dioxide isolation inner strip current confinement window) structure and a p-NiO as the capping layer (light confinement layer and hole injection layer) in the optical communication band (see the attached Figure 4 and the description of the drawings). It is composed of a substrate 1 from bottom to top, an n-type Si-doped (doping concentration range of 1.0×10 18 / cm 3 ~9.9×10 19 / cm 3 ) GaN epitaxial lower confinement layer (light, hole confinement layer and electron injection layer) 2 prepared on the substrate 1, an InN material active light-emitting layer 3 prepared on the GaN epitaxial lower confinement layer 2, a p-type Mg-doped (doping concentration range of 1.0×10 17 / cm 3 ~5.0×10 18 / cm 3 ) GaN 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, and its doping concentration range is 1×10 18 / cm 3 ~9.9×10 19 / cm 3 ; A silicon dioxide current isolation layer 10 is prepared on the GaN electron confinement layer 4. A strip-shaped current confinement window 11 is prepared on the silicon dioxide current isolation layer 10. A capping 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 capping layer 5 is p-NiO, and the hole concentration is 1.0×1018 / cm 3 ~9.9×10 20 / cm 3 ; The cap layer 5 contacts the GaN electron confinement layer 4 through the strip current confinement window 11, thereby injecting current; an upper electrode 6 is fabricated on the cap layer 5 to form a large-area ohmic contact; the front and rear end faces cleaved from the epitaxial chip along the plane perpendicular to the strip direction of the strip current confinement window 11 constitute the front mirror 8 and the rear mirror 9, and the light of the laser is emitted from the front mirror 8 and the rear mirror 9 under the strip current confinement window 11 after being generated in the active light-emitting layer 3.

[0010] Fabrication method: The GaN buffer layer 12 and the GaN epitaxial lower confinement layer (light and hole confinement layer and electron injection layer) 2 of the InN infrared light-emitting diode and laser with p-NiO as the cap layer (light confinement layer and hole injection layer) designed in the present invention are epitaxially grown by using the currently relatively mature conventional MOCVD (metal organic chemical vapor deposition) process. The InN material active light-emitting layer 3 and the GaN electron confinement layer 4 can be epitaxially grown by using the MBE (molecular beam epitaxy) process; at present, the processes for fabricating p-NiO thin film materials by MOCVD and MBE methods are not yet mature, so the p-NiO cap layer 5 is fabricated by magnetron sputtering. The material for fabricating 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 material such as Ti-Pt-Au, Ti-Ni-Au or Ni-Pt-Au, and the fabrication method can be thermal evaporation, electron beam evaporation or magnetron sputtering; the material for 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 and Ti-Al-Ni-Au, and the fabrication method can be thermal evaporation, electron beam evaporation or magnetron sputtering; generally, the materials for the upper and lower electrodes are different. For the fabrication of the laser: For the fabrication of the ridge stripe cap layer 5, after the epitaxial wafer is fabricated, a layer of p-NiO cap layer is first sputtered, then photolithography is carried out, masked with photoresist, and the p-NiO cap layer is etched with hot dilute sulfuric acid to form a ridge stripe structure. 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 cannot etch the GaN electron confinement layer 4; therefore, this etching solution is selected for the fabrication of the ridge stripe cap layer 5 instead of 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 limiting window 11 is carried out using conventional photolithography and silicon dioxide etching techniques or the photoresist lift-off technique; then, the substrate 1 can be thinned to 60 - 150 micrometers by conventional processes such as manual grinding or grinding machine grinding; finally, the epitaxial chip with upper and lower electrodes deposited is cleaved along the (1, 0, 0) or (1, 1, 0) plane of the substrate 1 (note that the strip direction of the prepared ridge-shaped cover layer 5 or the current limiting window 11 needs to be perpendicular to the direction of this cleavage plane) into bars with a width of 100 micrometers to 2 millimeters, and then the bars are sawn into die chips with a width of 100 micrometers to 500 micrometers, thus preparing a rectangular laser die chip. 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 at the front mirror 8 and the rear mirror 9. The original bar width is the cavity length of the laser resonator. The strip direction of the ridge-shaped cover layer 5 and the strip-shaped current limiting 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 manufacturing the laser device.

[0011] The preparation method of the optical communication band InN infrared light-emitting diode and laser with p-NiO as the cover layer (optical confinement layer and hole injection layer) according to the present invention is characterized in that: the GaN buffer layer 12 and the GaN epitaxial lower confinement layer 2 are prepared by the MOCVD method, the InN material active light-emitting layer 3 and the GaN electron confinement layer 4 are prepared by the MBE method, the p-NiO cover 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 optical communication band InN infrared light-emitting diode and laser with p-NiO as the cover layer (optical confinement layer and hole injection layer) prepared by the present invention utilize the characteristics that the InN material is a narrow direct bandgap material, suitable for preparing LEDs (light-emitting diodes) and LDs (laser diodes) around 1.55 µm in the near infrared applicable to the field of optical fiber communication. At the same time, by using the characteristics of p-NiO such as high hole concentration, low resistivity, wide bandgap, lower refractive index than the GaN material, and very low growth temperature, the device can have good hole injection, good optical confinement and carrier confinement, preparing a new type of infrared light-emitting diode and laser with good temperature characteristics, which can expand the application range of the device. Description of the Drawings

[0014] Figure 1: (a) Schematic diagram of the structure of an InN infrared light-emitting diode in the optical communication band with p-NiO as the cap layer (optical confinement layer and hole injection layer), (b) Schematic diagram of the upper electrode structure of the device.

[0015] Figure 2 : Schematic diagram of the structure of an InN infrared light laser in the optical communication band with p-NiO as the cap layer (optical confinement layer and hole injection layer).

[0016] Figure 3 : Schematic diagram of the structure of an InN infrared light laser in the optical communication band with p-NiO as the cap layer (optical confinement layer and hole injection layer) having a ridge stripe structure.

[0017] Figure 4 : Schematic diagram of the structure of an InN infrared red light laser in the optical communication band with an inner stripe structure and p-NiO as the cap layer.

[0018] Figure 5 : Emission spectra of the light-emitting diode composed of p-type GaN and InN in Example 1 at different injection currents at room temperature. It can be seen the feasibility of the designed structure emitting infrared light in the optical communication band.

[0019] Figure 6 : Electro-injection emission spectrum of the light-emitting diode composed of p-type GaN and InN in Example 1 at a high temperature of 110 °C. Figure 6 and Figure 5 By comparison, it can be seen that the peak of this 110 °C spectrum moves very little compared to the peak at room temperature, indicating that the temperature characteristics of this light-emitting device are very good.

[0020] Table 1: Hall test results of p-NiO thin film samples sputtered at different temperatures

[0021] 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 >

[0022] The names of each part in the figure are: substrate 1, GaN epitaxial lower confinement layer 2, InN material active light-emitting layer 3, GaN electron confinement layer 4, cap layer (optical 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 current confinement window 11, GaN buffer layer 12. Detailed implementation manners

[0023] The following describes in detail the specific embodiments and implementation processes of the present invention in combination with the technical solutions and drawings.

[0024] Example 1

[0025] The InN infrared light-emitting diode in the optical communication band with p-NiO as the cap layer (optical confinement layer and hole injection layer) is shown in the appendix Figure 1In (a). 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 grown at high temperature is relatively large, first, a 50-nm-thick undoped GaN buffer layer 12 is grown on the substrate 1 at a low temperature (550 °C) by MOCVD. Then, a 2-μm-thick n-type (doped with Si, doping concentration is 4×10 18 / cm 3 )GaN epitaxial lower confinement layer 2 is grown at a high temperature of 1030 °C by the conventional MOCVD process; Since the process for preparing InN thin film materials by the MOCVD method is not yet mature, the InN material light-emitting layer 3 and the GaN electron confinement layer 4 above the InN material light-emitting layer 3 are both prepared by the MBE method; After the epitaxial wafer is prepared, a p-NiO capping layer 5 is prepared on the GaN electron confinement layer 4 by magnetron sputtering; The thickness of the InN active light-emitting layer 3 is 100 nm, and the growth temperature is 480 °C; Since the hole concentration of the p-NiO capping layer 5 is very high, the electron confinement layer 4 (doped with Mg) can be prepared into a weakly p-type with a doping concentration of 10 17 / cm 3 That's all right. In order to prevent the InN material of the active light-emitting layer 3 from decomposing at high temperature, the GaN electron confinement layer 4 is grown in two steps. The first step is to grow 10 nm at 500 °C, and the second step is to grow 10 nm at 680 °C, with a total thickness of 20 nm; The MO sources used for epitaxially growing the n-type (doped with Si) GaN epitaxial lower confinement layer 2 on the substrate by the MOCVD process are: the gallium source is trimethylgallium (TMGa), the nitrogen source is ammonia (NH3), and the doped silicon source is silane (SiH4); The indium source used for preparing the InN active light-emitting layer and the GaN electron confinement layer by the MBE method is high-purity (99.99999% purity) indium, the gallium source used is high-purity (99.99999% purity) gallium, the magnesium source used for doping is high-purity (99.9999% purity) magnesium, and the nitrogen source is ionized nitrogen; The target source used for magnetron sputtering the p-NiO capping layer 5 is a ceramic target of NiO plus 2% by mass fraction of Li2O. Table 1 shows the Hall test results of the p-NiO thin film samples sputtered at different temperatures. We initially selected the temperature to be 150 °C, and the thickness of the p-NiO capping layer 5 is 200 nm; Then, the p-NiO capping layer 5, the GaN electron confinement layer 4, and the InN active light-emitting layer 3 in some areas are removed by conventional plasma etching technology for photolithography etching, and the GaN epitaxial lower confinement layer 2 is exposed in these areas; Then, a lower electrode 7 is deposited with Ni-Au in the areas where the GaN epitaxial lower confinement layer 2 is exposed by using the photoresist masking and lift-off technology (Lift of), and its thickness is about 300 nanometers; Then, an upper electrode 6 is deposited with Au in some areas of the p-NiO capping layer 5 by using the photoresist masking and lift-off technology. Its thickness is about 300 nanometers. In order to facilitate fiber coupling, the upper electrode 6 is made into an outer square and inner circular ring shape. See attached Figure 1In (b); then alloy annealing, the annealing temperature is 450 °C, and the time is 3 minutes; finally, dicing is performed to fabricate die. In the initial stage of the experiment, in order to test the light-emitting effect of this light-emitting diode, we developed a simple light-emitting diode composed of p-type GaN and InN. Figure 5 The electroluminescence spectrum of the light-emitting diode composed of p-type GaN and InN developed by us at room temperature. Figure 6 The high-temperature electroluminescence spectrum of the light-emitting diode composed of p-type GaN and InN developed by us.

[0026] Example 2

[0027] The InN infrared laser in the optical communication band with p-NiO as the cap layer (optical confinement layer and hole injection layer) is shown in the appendix Figure 2 . The preparation process is as follows: an n-type GaN crystal wafer (doping concentration is 5×10 18 / cm 3 ) is used as the substrate 1. Since a homo-substrate with a completely lattice-matched structure is used, there is no need to grow a buffer layer. Using the currently mature conventional MOCVD process, a 2-μm-thick n-type (doped with Si, doping concentration is 4×10 18 / cm 3 ) GaN epitaxial lower confinement layer 2 is directly grown on the n-type GaN crystal wafer substrate 1 at 1030 °C; since the process of preparing InN thin film materials by the current MOCVD method is not yet mature, the InN material light-emitting layer 3 and the GaN electron confinement layer 4 above the InN material light-emitting layer 3 are both prepared by the MBE method; after the epitaxial wafer is prepared, a p-NiO cap layer 5 is prepared on the GaN electron confinement layer 4 by magnetron sputtering; the undoped InN material active light-emitting layer 3 is 100 nm thick, and the growth temperature is 480 °C; since the hole concentration of the p-NiO cap layer 5 is very high, the GaN electron confinement layer 4 (doped with Mg) can be prepared into a weakly p-type with a doping concentration of 10 17 / cm 3That's all. To prevent the InN material in the active light-emitting layer 3 from decomposing at high temperatures, the GaN electron confinement layer 4 is grown in two steps. In the first step, it is grown at 500 °C for 10 nm, and in the second step, it is grown at 680 °C for 10 nm, with a total thickness of 20 nm. The MO source and MBE source used for epitaxial growth are the same as in Example 1. The target source for magnetron sputtering the p-NiO capping 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 a thickness of 200 nm for the p-NiO capping layer 5. Then, a metal is evaporated using a thermal evaporation stage or an electron beam evaporation stage to prepare the upper electrode 6 on the p-NiO capping layer 5. Then, the substrate is thinned to 90 microns, and a metal lower electrode 7 is evaporated on the substrate surface. Then, alloy annealing is carried out under the protection of an 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 into bars with a width of 1000 microns, 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. The original bar width is the cavity length of the laser resonator. The material of the upper electrode 6 is Au, and the material of the lower electrode 7 is Ni-Au, and their thicknesses are both about 300 nm.

[0028] Example 3

[0029] An InN infrared light laser in the optical communication band with a ridge mesa structure and a p-NiO capping layer (optical 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 (doping concentration of 5×10 18 / cm 3 ) is used as the substrate 1. Since a homogeneous substrate with a completely lattice-matched structure is used, there is no need to grow a buffer layer. Using the currently mature conventional MOCVD process, a 2-micron-thick n-type (doped with Si, doping concentration of 4×10 18 / cm 3 ) GaN epitaxial lower confinement layer 2 is directly grown on the n-type GaN crystal wafer substrate 1 at 1030 °C. Since the process of preparing InN thin film materials by the current MOCVD method is not yet mature, the InN material light-emitting layer 3 and the GaN electron confinement layer 4 above the InN material light-emitting layer 3 are both prepared by the MBE method. The undoped InN material active light-emitting layer 3 has a thickness of 100 nm and a growth temperature of 480 °C. Since the p-NiO capping layer 5 has a very high hole concentration, the GaN electron confinement layer 4 (doped with Mg) can be prepared into a weakly p-type with a doping concentration of 10 17 / cm 3That's all. To prevent the InN material of the active light-emitting layer 3 from decomposing at high temperatures, the GaN electron confinement layer 4 is grown in two steps. In the first step, it is grown at 500 °C for 10 nm, and in the second step, it is grown at 680 °C for 10 nm, with a total thickness of 20 nm. The MO source and MBE source used for epitaxial growth are the same as in Example 1. After the epitaxial wafer is prepared, a p-NiO capping layer 5 is prepared on the GaN electron confinement layer 4 by magnetron sputtering. The target source used for magnetron sputtering the p-NiO capping layer 5 is a ceramic target of NiO plus 2% by mass fraction of Li2O, the sputtering 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 capping 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 GaN electron confinement layer 4 is exposed outside the ridge-shaped strip p-NiO capping layer 5. The width of the ridge-shaped strip p-NiO capping layer 5 is 10 microns. Then, the photoresist is retained, and a layer of silicon dioxide current isolation layer 10 (with a thickness of 200 nm) is prepared on the ridge-shaped strip capping layer 5 and the exposed GaN electron confinement layer 4 by electron beam evaporation. Then, the photoresist is removed, and the silicon dioxide on the photoresist is peeled off and removed, thus 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 capping 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 the protection of inert gas, with an annealing temperature of 450 °C and a time of 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 capping 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 (square) 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 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 the material of the lower electrode 7 is Ni-Au, and their thicknesses are both about 300 nm.

[0030] Example 4

[0031] The optical communication band InN infrared laser with a p-NiO as the capping layer for the inner strip structure is shown in the appendix Figure 4 。 Its preparation process is as follows. An n-type GaN crystal wafer (doping concentration is 5×10 18 / cm 3is the substrate 1. Since a homo-substrate with a completely lattice-matched structure is used, there is no need to grow a buffer layer. Using the currently mature conventional MOCVD process, a 2-μm-thick n-type (doped with Si, doping concentration of 4×10 18 / cm 3 )GaN epitaxial lower confinement layer 2 is directly grown on the n-type GaN wafer substrate 1 at 1030 °C; since the current MOCVD method for preparing InN thin film materials is not yet mature, the InN material light-emitting layer 3 and the GaN electron confinement layer 4 on top of the InN material light-emitting layer 3 are both prepared by the MBE method; the undoped InN material active light-emitting layer 3 has a thickness of 100 nm and a growth temperature of 480 °C; since the hole concentration of the p-NiO capping layer 5 is very high, the GaN electron confinement layer 4 (doped with Mg) can be prepared into a weakly p-type with a doping concentration of 10 17 / cm 3 That's all. In order to prevent the InN material of the active light-emitting layer 3 from decomposing at high temperatures, the GaN electron confinement layer 4 is grown in two steps. The first step is to grow 10 nm at 500 °C, and the second step is to grow 10 nm at 680 °C, with a total thickness of 20 nm; then, a layer of silicon dioxide current isolation layer 10 is prepared on the electron confinement layer 4 by electron beam evaporation. A strip-shaped current confinement window 11 with a width of about 3 μm 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. The target source used for magnetron sputtering the p-NiO capping layer 5 is a ceramic target of NiO plus 2% by mass of Li2O, the sputtering temperature is 150 °C, and the thickness is 200 nm; then, an upper electrode 6 is prepared by evaporating metal on the p-NiO capping layer 5; the substrate is thinned to 90 μm, and then a metal lower electrode 7 is evaporated on the substrate surface. 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 into bars with a width of 1000 μm (note that the prepared current confinement window 11 needs to be perpendicular to the direction of this cleavage plane). Then, the bars are sawn into die chips with a width of 300 μm, thus preparing a rectangular (square) 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 current confinement window 11. The original bar width is the cavity length of the laser resonator. The bar 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 the material of the lower electrode 7 is Ni-Au, and their thicknesses are both about 300 nm.

Claims

1. An InN infrared light-emitting diode in the optical communication band with a p-NiO cap layer, which is composed of, from bottom to top, a substrate (1), a GaN buffer layer (12) prepared on the substrate (1), an n-type Si-doped GaN epitaxial lower confinement layer (2) prepared on the GaN buffer layer (12), a mutually discrete undoped InN material active light-emitting layer (3) and a lower electrode (7) prepared on the GaN epitaxial lower confinement layer (2), a p-type Mg-doped GaN electron confinement layer (4) prepared on the InN material active light-emitting layer (3), a cap layer (5) prepared on the GaN electron confinement layer (4), and an upper electrode (6) prepared on the cap 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 1.0×10 18 / cm 3 ~9.9×10 20 / cm 3 ; the upper electrode (6) is fabricated into an annular structure with a square outer and a circular inner shape, and the light generated in the active light-emitting layer (3) emits from the inner circle of the upper electrode (6).

2. An InN infrared light laser with p-NiO as the cap layer, which is composed of a substrate (1) from bottom to top in sequence, an n-type Si-doped GaN epitaxial lower confinement layer (2) prepared on the substrate (1), an undoped InN material active light-emitting layer (3) prepared on the GaN epitaxial lower confinement layer (2), a p-type Mg-doped GaN electron confinement layer (4) prepared on the InN material active light-emitting layer (3), a cap layer (5) prepared on the GaN electron confinement layer (4), an upper electrode (6) prepared on the cap layer (5), 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 doping concentration ranging from 1×10 18 / cm 3 to 9.9×10 19 / cm 3 ; the cap layer (5) is p-NiO with a hole concentration of 1.0×10 18 / cm 3 to 9.9×10 20 / cm 3 .

3. An InN infrared light laser with a ridge stripe structure and a p-NiO capping layer, which is composed of a substrate (1) from bottom to top, an n-type Si-doped GaN epitaxial lower confinement layer (2) prepared on the substrate (1), an undoped InN material active light-emitting layer (3) prepared on the GaN epitaxial lower confinement layer (2), a p-type Mg-doped GaN electron confinement layer (4) prepared on the InN material active light-emitting layer (3), 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 doping concentration ranging from 1×10 18 / cm 3 ~9.9×10 19 / cm 3 ; A cover layer (5) with a ridge strip structure is prepared on the GaN electron confinement layer (4). The cover layer (5) is p-NiO with a hole concentration of 1.0×10 18 / cm 3 ~9.9×10 20 / cm 3 ; A layer of silicon dioxide current isolation layer (10) is prepared on the cover layer (5) and the GaN electron confinement layer (4). A strip-shaped current confinement window (11) is prepared on the silicon dioxide current isolation layer (10) at the top of the ridge strip cover layer (5). An upper electrode (6) is prepared on the silicon dioxide current isolation layer (10) and the strip-shaped current confinement window (11). The upper electrode (6) is in contact with the cover layer (5) through the strip-shaped current confinement window (11) to inject current.

4. An InN infrared light laser with a p-NiO of an inner strip structure as the cap layer, which is successively composed of a substrate (1) from bottom to top, an n-type Si-doped GaN epitaxial lower confinement layer (2) prepared on the substrate (1), an InN material active light-emitting layer (3) prepared on the GaN epitaxial lower confinement layer (2), a p-type Mg-doped GaN electron confinement layer (4) prepared on the InN material active light-emitting layer (3), 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 doping concentration ranging from 1×10 18 / cm 3 ~9.9×10 19 / cm 3 ; A layer of silicon dioxide current isolation layer (10) is prepared on the GaN electron confinement layer (4). A strip-shaped current confinement window (11) is prepared on the silicon dioxide current isolation layer (10). A capping layer (5) is prepared on the silicon dioxide current isolation layer (10) and the strip-shaped current confinement window (11). The capping layer (5) is p-NiO with a hole concentration of 1.0×10 18 / cm 3 ~9.9×10 20 / cm 3 ; The capping layer (5) contacts the GaN electron confinement layer (4) through the strip-shaped current confinement window (11) for current injection; An upper electrode (6) is prepared on the capping layer (5) to form a large-area ohmic contact.

5. The preparation method of an InN infrared light-emitting diode with p-NiO as a cap layer as described in claim 1, characterized in that: The GaN buffer layer (12) and the n-type Si-doped GaN epitaxial lower confinement layer (2) are prepared by the MOCVD method. The InN material active light-emitting layer (3) and the p-type Mg-doped GaN electron confinement layer (4) are prepared by the MBE method. The p-NiO capping layer (5) is prepared by magnetron sputtering. The upper electrode (6) and the lower electrode (7) are prepared by thermal evaporation, electron beam evaporation or magnetron sputtering.

6. The preparation method of an InN infrared light laser with p-NiO as a cap layer according to claim 2, characterized in that: The n-type Si-doped GaN epitaxial lower confinement layer (2) is prepared by the MOCVD method. The InN material active light-emitting layer (3) and the p-type Mg-doped GaN electron confinement layer (4) are prepared by the MBE method. The p-NiO capping layer (5) is prepared by magnetron sputtering. The upper electrode (6) and the lower electrode (7) are prepared by thermal evaporation, electron beam evaporation or magnetron sputtering.

7. The preparation method of an InN infrared light laser with a p-NiO of a ridge platform strip structure as a cap layer according to claim 3, characterized in that: The n-type Si-doped GaN epitaxial lower confinement layer (2) is prepared by the MOCVD method. The InN material active light-emitting layer (3) and the p-type Mg-doped GaN electron confinement layer (4) are prepared by the MBE method. The p-NiO capping layer (5) is prepared by magnetron sputtering. The upper electrode (6) and the lower electrode (7) are prepared by thermal evaporation, electron beam evaporation or magnetron sputtering.

8. The manufacturing method of an InN infrared light laser with a p-NiO of a ridge platform strip structure as a cap layer as described in claim 7, characterized in that: The p-NiO capping layer (5) is etched with hot dilute sulfuric acid to form a ridge-shaped strip structure.

9. The preparation method of an InN infrared light laser with a p-NiO with an internal strip structure as a cover layer according to claim 4, characterized in that: The n-type Si-doped GaN epitaxial lower confinement layer (2) is prepared by the MOCVD method. The InN material active light-emitting layer (3) and the p-type Mg-doped GaN electron confinement layer (4) are prepared by the MBE method. The p-NiO capping layer (5) is prepared by magnetron sputtering. The upper electrode (6) and the lower electrode (7) are prepared by thermal evaporation, electron beam evaporation or magnetron sputtering.

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