A double heterojunction-based electrically pumped single-mode laser diode and a method for preparing the same

Abstract

The present invention discloses a double heterojunction-based electrically pumped single-mode laser diode and a preparation method thereof. The double heterojunction-based electrically pumped single-mode laser diode described in the invention comprises a p-GaN substrate, an n-AlGaN substrate, a PtNPs@ZnO:Ga composite micrometer wire, a MgO low dielectric insulating layer, a Pt nanofilm layer, and a Ni / Au thin film electrode; the preparation method combines a p-GaN substrate and an n-AlGaN substrate and introduces a MgO low dielectric insulating layer and a Pt nanofilm layer as a buffer layer in the device, and uses Pt nanoparticles to modify the ZnO micrometer wire, thereby constructing a double heterojunction-based electrically pumped single-mode laser diode. Compared with the prior art, the present invention can effectively confine the optical field to increase the gain and reduce the optical loss at the interface, improve the injection efficiency of carriers, and realize high-quality electrically pumped single-mode laser under forward bias.

Description

Technical Field

[0001] The invention relates to a laser diode and a preparation method thereof, in particular to a double heterojunction-based electrically pumped single-mode laser diode and a preparation method thereof. Background Art

[0002] In recent years, electrically pumped micro-nano lasers have broad application prospects in the fields of optical interconnection, optical communication, biosensing, medical imaging, 3D display, etc. One-dimensional ZnO micro-nanowires are direct bandgap wide-bandgap semiconductor materials of the II-VI group. Their bandgap width is about 3.37eV, and the exciton binding energy is as high as 60meV at room temperature. They are widely used in light-emitting diodes and detectors in the ultraviolet band. In addition, the micro-nano structure of ZnO has excellent single crystals, natural optical resonators, and controllable structures and morphologies. It is an ideal material for realizing efficient light emission and low-threshold laser devices. However, due to the existence of intrinsic defects such as O vacancies and Zn interstitial atoms, ZnO crystals exhibit n-type conductivity, while p-type ZnO doping is difficult and difficult to prepare. There are still many problems in preparing efficient, stable and repeatable p-ZnO materials. Finding p-type materials with mature preparation technology to replace p-ZnO to construct ZnO-based heterojunctions has become a research hotspot, including p-Si, p-SnO2, p-NiO, p-Co3O4, p-GaN, etc. Among them, GaN materials with the same wurtzite structure have very similar physical properties to ZnO. The lattice mismatch rate of GaN materials with a bandgap width of 3.39eV and ZnO is only 1.9%. Therefore, n-ZnO / p-GaN heterojunction light-emitting devices have been developed and studied by many researchers.

[0003] The device structure is of great significance for the development of high-performance semiconductor micro-nano lasers. By designing the device structure, the performance of electrically pumped micro-nano lasers can be effectively improved. In electrically pumped micro-nano lasers, not only is the optical loss on the interface still a greater challenge compared to optically pumped micro-nano lasers, but carrier transport and electrical contact are also particularly important. Therefore, it is necessary to construct a new type of composite heterostructure to realize high-quality electrically pumped single-mode laser diodes based on double heterojunctions. Summary of the invention

[0004] Purpose of the invention: To solve the above problems, the present invention provides a double heterojunction-based electrically pumped single-mode laser diode and a method for preparing the same, which can effectively confine the light field to increase the gain and reduce the optical loss at the interface, thereby improving the carrier injection efficiency and achieving high-quality electrically pumped single-mode laser under forward bias.

[0005] Technical solution: To achieve the above-mentioned purpose, the technical solution adopted by the double heterojunction-based electrically pumped single-mode laser diode described in the present invention is specifically as follows: the double heterojunction-based electrically pumped single-mode laser diode includes a p-GaN substrate, an n-AlGaN substrate, a first Ni / Au thin film electrode connected to the p-GaN substrate, a second Ni / Au thin film electrode connected to the n-AlGaN substrate, a MgO low dielectric insulating layer arranged on the surface of the p-GaN substrate, a Pt nano-film layer arranged on the surface of the MgO low dielectric insulating layer, and a PtNPs@ZnO:Ga composite micron wire arranged between the Pt nano-film layer and the n-AlGaN substrate, and the composite micron wire is simultaneously connected to the Pt nano-film layer and the n-AlGaN substrate.

[0006] Furthermore, the p-GaN substrate has a thickness of 2 to 5 μm, a size of 1.0 cm×0.5 cm, and a hole concentration of 10 17 ~10 19 / cm 3 , the hole mobility is 5 to 100 cm 2 / V·s; the n-AlGaN substrate has a thickness of 2 to 5 μm, a size of 1.0 cm×0.5 cm, and an electron concentration of 10 17 ~10 18 / cm 3 , the electron mobility is 5~50cm 2 / V·s.

[0007] Furthermore, the thickness of Ni and Au in the first Ni / Au thin film electrode and the second Ni / Au thin film electrode are 50 nm and 50 nm respectively.

[0008] The technical scheme adopted by the preparation method of the double heterojunction-based electrically pumped single-mode laser diode of the present invention is as follows: (1) annealing and cleaning the p-GaN substrate and the n-AlGaN substrate respectively; (2) evaporating a first Ni / Au thin film electrode as an anode on the p-GaN substrate; (3) evaporating a second Ni / Au thin film electrode as a cathode on the n-AlGaN substrate; (4) evaporating a MgO low dielectric insulating layer and a Pt nano-thin film layer of the same thickness on the p-GaN substrate in sequence; (5) selecting ZnO:Ga micrometer wires, and sputtering a layer of Pt quasiparticle film using a plasma magnetron sputtering instrument, The composite structure of Pt@ZnO:Ga metal-modified semiconductor is formed; (6) the composite structure of Pt@ZnO:Ga metal-modified semiconductor is subjected to electric current heating and annealing by Joule heating effect to convert the Pt quasi-particle nanofilm into isolated nanoparticles, thereby obtaining PtNPs@ZnO:Ga composite micron-wire; (7) under an optical microscope, the prepared PtNPs@ZnO:Ga composite micron-wire is placed on the Pt nano-film layer, and then the n-AlGaN substrate is pressed onto the PtNPs@ZnO:Ga composite micron-wire and fixed, thereby forming a double heterojunction-based electrically pumped single-mode laser diode.

[0009] Furthermore, the substrate annealing is to place the p-GaN substrate and the n-AlGaN substrate in a high temperature furnace for annealing respectively, the annealing temperature is 700-900° C., and the annealing time is 1-2 hours.

[0010] Furthermore, the substrate is cleaned by placing the substrate in a trichloroethylene solution after annealing, and ultrasonically cleaning it in an ultrasonic cleaning instrument for 15 minutes; then ultrasonically cleaning it in acetone, ethanol, and deionized water for 15 minutes each, and then blowing it dry with nitrogen.

[0011] Furthermore, the length of the ZnO:Ga micrometer wire is 0.5 to 1 cm, and the electron concentration is 10 17 ~10 19 / cm 3 , the electron mobility is 5~100cm 2 / V·s, Ga doping concentration is less than 1%.

[0012] Furthermore, the p-GaN substrate is plated with a region other than the first Ni / Au thin film electrode, and a MgO low dielectric insulating layer and a Pt nano-thin film layer with a thickness of 10 nm are sequentially deposited by a metal organic chemical vapor deposition system at a deposition rate of

[0013] Furthermore, the sputtering of a layer of Pt quasiparticle film uses a Pt target as a sputtering target, the target specification is 50.8×1.0 mm, the purity is 99.99%, the working gas is argon, the chamber pressure is 30 Pa, the sputtering current is 30 mA, and the sputtering time is 300 s.

[0014] Furthermore, the current heating is to place the composite structure of Pt@ZnO:Ga metal-modified semiconductor on a quartz substrate, press indium particles at both ends as electrodes to connect current and adjust the current to 3-6 mA to make the composite structure emit weak light.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following significant effects: effectively confining the light field to increase the gain and reduce the light loss at the interface, improving the carrier injection efficiency, and realizing high-quality electrically pumped single-mode laser under forward bias. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the cross-sectional structure of the device of the present invention.

[0017] Figure 2 It is a schematic diagram of the top view structure of the device of the present invention.

[0018] Figure 3 A flow chart was prepared for the inventive device.

[0019] Figure 4 This is the IV characteristic curve of the device of the present invention.

[0020] Figure 5 The laser spectrum diagram of the device of the present invention at different working currents.

[0021] Figure 6 This is a laser spectrum diagram of the device of the present invention when the current is 28.2 mA.

[0022] Figure 7 This is an electroluminescent effect diagram of the device of the present invention under a microscope. DETAILED DESCRIPTION

[0023] The present invention discloses a double heterojunction-based electrically pumped single-mode laser diode and a method for preparing the same. Figure 1 , Figure 2As shown, the double heterojunction-based electrically pumped single-mode laser diode provided by the present invention is further described in detail below: The double heterojunction-based high-quality electrically pumped single-mode laser diode includes a p-GaN substrate 1, an n-AlGaN substrate 2, a first Ni / Au thin film electrode 6 connected to the p-GaN substrate 1, a second Ni / Au thin film electrode 7 connected to the n-AlGaN substrate 2, a MgO low dielectric insulating layer 4 arranged on the surface of the p-GaN substrate 1, a Pt nano-film layer 5 arranged on the surface of the MgO low dielectric insulating layer 4, and a PtNPs@ZnO:Ga composite micron wire 3 arranged between the Pt nano-film layer 5 and the n-AlGaN substrate 2, and the composite micron wire 3 is connected to the Pt nano-film layer 5 and the n-AlGaN substrate 2 at the same time. Among them, the p-GaN substrate 1 has a specification of 1.0cm×0.5cm, a thickness of 2-5μm, and a hole concentration of 10 18 ~10 19 / cm 3 , the hole mobility is 5 to 100 cm 2 / V·s; the n-AlGaN substrate 2 has a size of 1.0cm×0.5cm, a thickness of 2 to 5μm, and an electron concentration of 10 17 ~10 18 / cm 3 , the electron mobility is 5~50cm 2 / V·s.

[0024] See also Figure 3 As shown, the preparation method provided by the present invention is further described in detail below: The preparation method of a double heterojunction-based high-quality electrically pumped single-mode laser diode comprises the following steps:

[0025] Step 1: anneal the p-GaN substrate 1 and the n-AlGaN substrate 2 in a high temperature furnace at 900°C for 1 hour, then use trichloroethylene, acetone, ethanol and deionized water to clean the annealed substrates in an ultrasonic instrument for 15 minutes and then blow dry with nitrogen.

[0026] Step 2: Use a mask to cover a portion of the p-GaN substrate 1 and expose a portion. Use a metal organic chemical vapor deposition system to plate a first Ni / Au thin film electrode 6 with a thickness of 50nm / 50nm on the exposed portion of the p-GaN substrate 1, and test the ohmic characteristics of the electrode.

[0027] Step 3: Use a mask to cover a portion of the n-AlGaN substrate 2 and expose a portion of it. Use a metal organic chemical vapor deposition system to plate a second Ni / Au thin film electrode 7 with a thickness of 50nm / 50nm on the exposed portion of the n-AlGaN substrate 2, and test the ohmic characteristics of the electrode.

[0028] Step 4: On the area outside the first Ni / Au thin film electrode 6 on the p-GaN substrate 1, a MgO low dielectric insulating layer 4 and a Pt nano-thin film layer 5 with a thickness of 10 nm are sequentially deposited by a metal organic chemical vapor deposition system at a deposition rate of

[0029] Step 5: Select high-quality ZnO:Ga microwires with a length of 0.5 to 1 cm and an electron concentration of 10 17 ~10 19 / cm 3 , the electron mobility is 5~100cm 2 / V·s; then a plasma magnetron sputtering device is used to sputter a dense Pt quasiparticle film on the surface of the ZnO:Ga micron wire to obtain a composite structure of Pt@ZnO:Ga metal-modified semiconductor; the sputtering target used in this process is Pt target with a specification of 50.8×1.0mm and a purity of 99.99%. The working gas is argon, the chamber pressure is 30Pa, the sputtering current is 30mA, and the sputtering time is 300s.

[0030] Step 6: Place the composite structure of Pt@ZnO:Ga metal-modified semiconductor on a quartz substrate, press indium particles at both ends as electrodes, connect current and adjust the current to 3-6 mA to make it emit weak light, and transform the Pt quasi-particle nanofilm on the surface of ZnO:Ga microwire into isolated nanoparticles through Joule heating effect. Remove the indium particles after taking down the ZnO:Ga microwire to obtain PtNPs@ZnO:Ga composite microwire 3.

[0031] Step 7: Under an optical microscope, the prepared PtNPs@ZnO:Ga composite microwire 3 is placed on a Pt nanofilm layer 5 with a thickness of 10 nm on a p-GaN substrate 1, so that the PtNPs@ZnO:Ga composite microwire 3 and the p-GaN substrate 1 are in full contact, and then an n-AlGaN substrate 2 coated with a first Ni / Au thin film electrode 6 as a cathode is pressed onto the PtNPs@ZnO:Ga composite microwire 3 and fixed, thereby forming a double heterojunction-based high-quality electrically pumped single-mode laser diode.

[0032] Step 8: Conduct electrical tests on the n-AlGaN / n-PtNPs@ZnO:Ga / Pt / MgO / p-GaN double heterojunction-based electrically pumped single-mode laser diode formed in step 7 and take luminescence photos, such as Figure 4 , 5 , 6, and 7. Figure 4 The current-voltage curve of the device is shown, and the device has typical rectification characteristics with a turn-on voltage of about 4.0V. In addition, the leakage current is about 0.02mA under 20V reverse bias. Figure 5The EL spectra of the device under different forward injection currents are shown. When the injection current is as low as 14.5 mA, only a wide spontaneous radiation band is observed. When the injection current increases to 16.8 mA, a peak suddenly appears at ~387.3 nm, indicating that laser action occurs in the microcavity. As the injection current increases, it can be seen that the spectrum of the double heterojunction-based high-quality electrically pumped single-mode laser diode changes from spontaneous radiation to stimulated radiation, thereby emitting high-quality single-mode laser. Figure 6 It shows that the half-peak width of the EL spectrum of the device is 0.05nm and the quality factor is 7746 at a current of 28.2mA. Figure 7 The optical microscope CCD image of the device emission light under different working currents is shown. Bright purple light emission can be clearly observed from the image. Therefore, by constructing a high-quality electrically pumped single-mode laser diode based on a double heterojunction, high-quality electrically pumped single-mode laser is achieved.

Claims

1. A double heterojunction-based electrically pumped single-mode laser diode, characterized in that: The invention comprises a p-GaN substrate (1), an n-AlGaN substrate (2), a first Ni / Au thin film electrode (6) connected to the p-GaN substrate (1), a second Ni / Au thin film electrode (7) connected to the n-AlGaN substrate (2), a MgO low dielectric insulating layer (4) arranged on the surface of the p-GaN substrate (1), a Pt nano-film layer (5) arranged on the surface of the MgO low dielectric insulating layer (4), and a PtNPs@ZnO:Ga composite micron wire (3) arranged between the Pt nano-film layer (5) and the n-AlGaN substrate (2); the composite micron wire (3) is connected to the Pt nano-film layer (5) and the n-AlGaN substrate (2) at the same time.

2. The double heterojunction-based electrically pumped single-mode laser diode according to claim 1, characterized in that: The p-GaN substrate (1) has a thickness of 2 to 5 μm, a size of 1.0 cm×0.5 cm, and a hole concentration of 10 17 ~10 19 / cm 3 , the hole mobility is 5 to 100 cm 2 / V·s; the n-AlGaN substrate (2) has a thickness of 2 to 5 μm, a size of 1.0 cm×0.5 cm, and an electron concentration of 10 17 ~10 18 / cm 3 , the electron mobility is 5~50cm 2 / V·s.

3. The double heterojunction-based electrically pumped single-mode laser diode according to claim 1, characterized in that: The thicknesses of Ni and Au in the first Ni / Au thin film electrode (6) and the second Ni / Au thin film electrode (7) are 50 nm and 50 nm respectively.

4. A method for preparing a double heterojunction-based electrically pumped single-mode laser diode as claimed in any one of claims 1 to 3, characterized in that: The steps include: 1) annealing and cleaning the p-GaN substrate (1) and the n-AlGaN substrate (2) respectively; 2) vapor-depositing a first Ni / Au thin film electrode (6) as an anode on the p-GaN substrate (1); 3) vapor-depositing a second Ni / Au thin film electrode (7) as a cathode on the n-AlGaN substrate (2); 4) sequentially evaporating a MgO low dielectric insulating layer (4) and a Pt nano-thin film layer (5) of the same thickness on a p-GaN substrate (1); 5) Select ZnO:Ga micrometer wires and sputter a layer of Pt quasiparticle film using a plasma magnetron sputtering device to form a composite structure of Pt@ZnO:Ga metal-modified semiconductor; 6) subjecting the composite structure of Pt@ZnO:Ga metal-modified semiconductor to electric current heating and annealing using the Joule heating effect to convert the Pt quasi-particle nanofilm into isolated nanoparticles, thereby obtaining PtNPs@ZnO:Ga composite microwires (3); 7) Under an optical microscope, the prepared PtNPs@ZnO:Ga composite microwire (3) is placed on the Pt nanofilm layer (5), and then the n-AlGaN substrate (2) is pressed onto the PtNPs@ZnO:Ga composite microwire (3) and fixed, thereby forming a double heterojunction-based electrically pumped single-mode laser diode.

5. The method for preparing a double heterojunction-based electrically pumped single-mode laser diode according to claim 4, characterized in that: The substrate annealing in step 1) is to place the p-GaN substrate (1) and the n-AlGaN substrate (2) in a high temperature furnace for annealing respectively, the annealing temperature is 700-900° C., and the annealing time is 1-2 hours.

6. The method for preparing a double heterojunction-based electrically pumped single-mode laser diode according to claim 4, characterized in that: The substrate cleaning in step 1) is to place the substrate in a trichloroethylene solution after annealing, and ultrasonically clean it in an ultrasonic cleaning instrument for 15 minutes; then ultrasonically clean it in acetone, ethanol, and deionized water for 15 minutes each, and then blow dry it with nitrogen.

7. The method for preparing a double heterojunction-based electrically pumped single-mode laser diode according to claim 4, characterized in that: The length of the ZnO:Ga micrometer wire is 0.5 to 1 cm, and the electron concentration is 10 17 ~10 19 / cm 3 , the electron mobility is 5~100cm 2 / V·s, Ga doping concentration is less than 1%.

8. The method for preparing a double heterojunction-based electrically pumped single-mode laser diode according to claim 4, characterized in that: The p-GaN substrate (1) is plated with a region other than the first Ni / Au thin film electrode (6), and a MgO low dielectric insulating layer (4) and a Pt nano-thin film layer (5) with a thickness of 10 nm are sequentially evaporated using a metal organic chemical vapor deposition system at a deposition rate of 9. The method for preparing a double heterojunction-based electrically pumped single-mode laser diode according to claim 4, characterized in that: In the step 5), a layer of Pt quasiparticle film is sputtered using a Pt target material as a sputtering target material, the target material has a specification of 50.8×1.0 mm, a purity of 99.99%, an argon gas as the working gas, a chamber pressure of 30 Pa, a sputtering current of 30 mA, and a sputtering time of 300 s.

10. The method for preparing a double heterojunction-based electrically pumped single-mode laser diode according to claim 4, characterized in that: The current heating in step 6) is to place the composite structure of Pt@ZnO:Ga metal-modified semiconductor on a quartz substrate, press indium particles at both ends as electrodes, connect current and adjust the current to 3-6 mA to make the composite structure emit weak light.

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