FP ultraviolet laser based on GaN nanoribbons and its preparation and mode control method

Abstract

The present invention discloses a Fabry-Perot ultraviolet laser based on GaN nanoribbons, a preparation method thereof, and a laser mode control method. The laser provided by the present invention comprises: GaN nanoribbons, quartz glass, and indium particles, wherein the GaN nanoribbons are fixed on the quartz glass by the indium particles; the GaN nanoribbons are prepared by sequentially undergoing ultraviolet lithography, ICP dry etching, and electrochemical stripping of GaN epitaxial wafers. The present invention also provides a laser mode control method, comprising controlling the cavity size of the GaN nanoribbons by changing the wet etching time of the KOH solution to achieve laser mode control. The Fabry-Perot ultraviolet laser based on GaN nanoribbons disclosed by the present invention has a simple structure, is easy to prepare, has a low laser threshold, a high quality factor, and has excellent laser performance; the laser mode control method disclosed by the present invention can quickly achieve stable single-mode laser output, and provides certain technical support for the preparation of high-performance single-mode lasers.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor optoelectronic devices, and in particular to an ultraviolet laser based on GaN nanobelts, a preparation method thereof, and a laser mode control method. Background Art

[0002] Lasers generate photons by stimulated radiation, and these photons have exactly the same frequency and phase. Therefore, lasers have the advantages of good coherence and high polarization, which makes them have broad application prospects in the fields of biosensing, information storage, photon integration, nano-analysis, etc. Gallium nitride (GaN), as one of the representatives of the third-generation wide-bandgap semiconductor materials, has excellent properties such as high carrier mobility, low heat generation rate, good physical and chemical stability, and a wide direct bandgap (3.4eV), and has been widely used in the preparation of GaN-based ultraviolet lasers.

[0003] The resonant modes of the laser include random scattering mode, whispering gallery mode, and Fabry-Perot mode. The Fabry-Perot (FP) optical resonant cavity is composed of two mirrors with high reflectivity separated by a certain distance. However, the existing GaN-based FP ultraviolet lasers have difficulties such as complex structural design, difficult preparation of reflective mirrors, and incompatibility with existing Si-based integration processes. In addition, once the FP cavity is successfully prepared, its cavity size is no longer adjustable, which seriously limits its application in the field of tunable semiconductor lasers. Therefore, it is very important to develop a GaN-based FP ultraviolet laser with a simple structure, easy preparation, adjustable laser mode, and flexible compatibility with existing integration technologies. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a method for preparing a Fabry-Perot ultraviolet laser based on GaN nanoribbons and a method for controlling its mode.

[0005] Technical solution: The GaN nanoribbon-based Fabry-Perot ultraviolet laser of the present invention comprises GaN nanoribbons, quartz glass, and indium particles, wherein the GaN nanoribbons are fixed on the quartz glass via the indium particles.

[0006] Furthermore, the GaN nanobelt has a thickness of 100 nm to 300 nm, a width of 2000 nm to 3000 nm, and a length of 50 μm to 100 μm.

[0007] Furthermore, when excited by a femtosecond pump source of 325 nm at a certain power, the GaN nanoribbon generates an emission spectrum with a half-width of about 0.3 nm; the emission spectrum has good FP laser characteristics; the certain power means that the light intensity of the pump source is higher than the lasing threshold of the GaN nanoribbon; the lasing threshold of the GaN nanoribbon is an inherent property of the GaN nanoribbon.

[0008] The invention also discloses a method for preparing a Fabry-Perot ultraviolet laser based on GaN nanobelts. The GaN nanobelts are prepared by sequentially performing ultraviolet lithography, ICP dry etching and electrochemical stripping on a GaN epitaxial wafer.

[0009] Further, the following steps are included:

[0010] (1) using a metal organic chemical deposition (MOCVD) system to grow an undoped GaN nucleation layer on a c-plane sapphire substrate, wherein the thickness of the nucleation layer is 500 nm to 1000 nm;

[0011] (2) growing a heavily doped GaN sacrificial layer on the nucleation layer, wherein the thickness of the sacrificial layer is 1500 nm to 2500 nm, the doping element of the heavily doped GaN layer is Si, and the doping concentration of Si is 1×10 19 ~2×10 19 cm -3 ;

[0012] (3) Growing an undoped GaN target layer on the sacrificial layer, wherein the thickness of the target layer is 100 nm to 300 nm, to obtain a GaN epitaxial wafer.

[0013] Furthermore, the ultraviolet lithography is characterized by: forming a photoresist layer with a stripe array pattern on the surface of the GaN epitaxial wafer through mature industry-recognized ultraviolet lithography technology, which serves as a mask for ICP dry etching.

[0014] Furthermore, it is characterized in that the ICP dry etching is characterized in that: by using the ICP dry etching technology, the GaN epitaxial wafer is ICP dry etched with the photoresist of the stripe array pattern as a mask; the etching depth is 200nm to 500nm; and an intermediate product containing a nanobelt stripe array is obtained.

[0015] Furthermore, it is characterized in that the intermediate product containing the nanobelt stripe array is subjected to electrochemical stripping to corrode the heavily doped GaN sacrificial layer to obtain GaN nanobelts; the electrolyte for the electrochemical stripping is an oxalic acid solution with a concentration of 0.3 mol / L; the voltage of the electrochemical stripping is 10 to 15 V and the time is 5 to 10 min.

[0016] The present invention also discloses a debugging method for a Fabry-Perot ultraviolet laser based on a GaN nanobelt, which controls the cavity size of the GaN nanobelt and changes the optical path to achieve regulation of the laser mode; the KOH solution has a solubility of 2 mol / L, the corrosion temperature is 80°C, and the corrosion time is 1 min to 10 min.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: GaN nanobelts can be used as both gain media and natural FP resonant cavities, and are currently the most promising nanolasers. By controlling the size of the nanobelts, the preparation of single-mode ultraviolet lasers can be quickly realized. The GaN nanobelt-based FP ultraviolet laser has a simple structure, convenient preparation, and adjustable laser mode. It is also flexible and compatible with existing integrated technologies, making it have broad application prospects in the fields of biosensing, information storage, photon integration, and nanoanalysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a SEM image of a single ZnO microwire in an embodiment of the present invention;

[0019] Figure 2 It is a schematic structural diagram of the GaN nanoribbon FP ultraviolet laser of the present invention;

[0020] Figure 3 This is a schematic diagram of stimulated emission spectra of the GaN nanoribbon FP ultraviolet laser under different excitation powers in an embodiment of the present invention;

[0021] Figure 4 Schematic diagram of KOH solution etching GaN nanoribbons in an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of stimulated emission spectra of a GaN nanoribbon FP single-mode ultraviolet laser at different excitation powers after wet etching with a KOH solution for 10 minutes in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0024] A GaN nanobelt-based Fabry-Perot ultraviolet laser comprises: a GaN nanobelt, quartz glass, and indium particles, wherein the GaN nanobelt is fixed on the quartz glass via the indium particles.

[0025] The GaN nanobelt has a thickness of 100nm to 300nm, a width of 2000nm to 3000nm, and a length of 50μm to 100μm.

[0026] The GaN nanobelt generates an emission spectrum with a half-width of about 0.3 nm under the excitation of a femtosecond pump source of a certain power of 325 nm; the emission spectrum has good FP laser characteristics.

[0027] The certain power refers to that the light intensity of the pump source is higher than the lasing threshold of the GaN nanoribbon; the lasing threshold of the GaN nanoribbon is an inherent property of the GaN nanoribbon.

[0028] A corresponding preparation method of a FP ultraviolet laser based on GaN nanobelts includes: preparing GaN epitaxial wafers into GaN nanobelts by ultraviolet lithography, ICP dry etching and electrochemical stripping in sequence, transferring the GaN nanobelts to quartz glass, and fixing them with indium particles.

[0029] The method for preparing the GaN epitaxial wafer comprises the following steps:

[0030] (1) using a metal organic chemical deposition (MOCVD) system to grow an undoped GaN nucleation layer on a c-plane sapphire substrate, wherein the thickness of the nucleation layer is 500 nm to 1000 nm;

[0031] (2) growing a heavily doped GaN sacrificial layer on the nucleation layer, wherein the thickness of the sacrificial layer is 1500 nm to 2500 nm, the doping element of the heavily doped GaN layer is Si, and the doping concentration of Si is 1×10 19 ~2×10 19 cm -3 ;

[0032] (3) Growing an undoped GaN target layer on the sacrificial layer, wherein the thickness of the target layer is 100 nm to 300 nm, to obtain a GaN epitaxial wafer.

[0033] The ultraviolet lithography refers to: forming a photoresist layer with a stripe array pattern on the surface of the GaN epitaxial wafer through mature industry-recognized ultraviolet lithography technology, which serves as a mask for ICP dry etching.

[0034] The ICP dry etching refers to: using the mature industry-recognized ICP dry etching technology, using the photoresist with the stripe array pattern as a mask, ICP dry etching the GaN epitaxial wafer; the etching depth is 200nm to 500nm; and obtaining an intermediate product containing a nanobelt stripe array.

[0035] The electrochemical stripping refers to: electrochemically stripping the intermediate product containing the nanobelt stripe array, corroding the heavily doped GaN sacrificial layer to obtain GaN nanobelts; the electrolyte of the electrochemical stripping is oxalic acid solution with a concentration of 0.3 mol / L; the voltage of the electrochemical stripping is 10 to 15 V, and the time is 5 to 10 minutes.

[0036] A laser mode control method based on GaN nanobelt FP ultraviolet laser is to control the cavity size of GaN nanobelt and change the optical path by controlling the wet etching time of KOH solution to achieve laser mode control.

[0037] The KOH solution has a solubility of 2 mol / L.

[0038] The corrosion temperature is 80°C.

[0039] The corrosion time is 1 min to 10 min.

[0040] The following is a detailed description of a GaN nanoribbon-based Fabry-Perot ultraviolet laser, a preparation method thereof, and a laser mode control method provided by the present invention in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0041] Example:

[0042] Using MOCVD technology, a 500nm thick undoped GaN nucleation layer was grown on a c-plane sapphire substrate; a 1500nm thick heavily doped GaN sacrificial layer was grown on the nucleation layer, where the doping element was Si and the doping concentration was 1.5×10 19 cm -3 ; A 300nm thick undoped GaN target layer is grown on the sacrificial layer to obtain a GaN epitaxial wafer.

[0043] A photoresist layer with a stripe array pattern is formed on the surface of the GaN epitaxial wafer through mature industry-recognized ultraviolet lithography technology, which serves as a mask for ICP dry etching; the stripe width of the stripe array photoresist layer is 3μm and the period is 6μm.

[0044] By using the mature industry-recognized ICP dry etching technology, the GaN epitaxial wafer is subjected to ICP dry etching using the stripe array pattern photoresist as a mask; the etching depth is 400nm; and an intermediate product containing a nanobelt stripe array is obtained.

[0045] The intermediate product containing the nanobelt stripe array is subjected to electrochemical stripping to etch away the heavily doped GaN sacrificial layer to obtain GaN nanobelts; the electrochemical stripping electrolyte is an oxalic acid solution with a concentration of 0.3 mol / L, a voltage of 10 V, and a time of 10 min; independent 3 μm wide, 300 nm thick, 60 μm long GaN nanobelts such as Figure 1 shown.

[0046] The obtained independent GaN nanoribbons were transferred to a quartz substrate using a thermal release tape and fixed with indium particles to prepare a GaN nanoribbon FP UV laser, as shown in the schematic diagram. Figure 2 shown.

[0047] Through the self-built micro-area test system, the 325nm femtosecond pump source of different powers is focused onto the surface of the GaN nanobelt, and the GaN nanobelt is stimulated to emit, and the FP ultraviolet laser is obtained and collected by the spectrometer. The schematic diagram of the stimulated emission spectrum of the GaN nanobelt FP ultraviolet laser at different excitation powers is shown in the figure. Figure 3 shown.

[0048] The independent GaN nanobelts were immersed in a 2 mol / L KOH solution at 80°C for 10 min. Because the KOH solution has the characteristic of anisotropically corroding GaN, it can preferentially corrode the m-plane GaN. Figure 4 As shown, the corrosion rate is about 100nm / min.

[0049] By controlling the wet etching time of KOH solution, the cavity size of GaN nanoribbon is controlled, the optical path is changed, and the laser mode is regulated. Figure 5 Schematic diagram of the stimulated emission spectrum of the GaN nanoribbon FP single-mode UV laser at different excitation powers after 10 minutes of wet etching with KOH solution.

Claims

1. A FP ultraviolet laser based on GaN nanoribbons, characterized in that: It includes GaN nanobelts, quartz glass, and indium particles. The GaN nanobelts are prepared by ICP dry etching, and the GaN nanobelts are fixed on the quartz glass by indium particles. The independent GaN nanobelts are immersed in KOH solution, and the cavity size of the GaN nanobelts is controlled by controlling the wet etching time of the KOH solution, thereby changing the optical path and realizing the regulation of the laser mode.

2. The FP ultraviolet laser based on GaN nanoribbons according to claim 1, characterized in that: The GaN nanobelt has a thickness of 100 nm to 300 nm, a width of 2000 nm to 3000 nm, and a length of 50 μm to 100 μm.

3. The FP ultraviolet laser based on GaN nanoribbons according to claim 1, characterized in that: When excited by a femtosecond pump source of 325 nm at a certain power, the GaN nanoribbon generates an emission spectrum with a half-width of about 0.3 nm; the emission spectrum has good FP laser characteristics; the certain power means that the light intensity of the pump source is higher than the lasing threshold of the GaN nanoribbon; the lasing threshold of the GaN nanoribbon is an inherent property of the GaN nanoribbon.

4. A method for preparing a FP ultraviolet laser based on GaN nanoribbons according to claim 1, characterized in that: The GaN nanobelt is prepared by sequentially performing ultraviolet lithography, ICP dry etching and electrochemical stripping on a GaN epitaxial wafer.

5. The method for preparing a FP ultraviolet laser based on GaN nanoribbons according to claim 4, characterized in that: The steps include: (1) using a metal organic chemical deposition (MOCVD) system to grow an undoped GaN nucleation layer on a c-plane sapphire substrate, wherein the thickness of the nucleation layer is 500 nm to 1000 nm; (2) growing a heavily doped GaN sacrificial layer on the nucleation layer, wherein the thickness of the sacrificial layer is 1500 nm to 2500 nm, the doping element of the heavily doped GaN layer is Si, and the doping concentration of Si is 1×10 19 ~ 2×10 19 cm -3 ; (3) Growing an undoped GaN target layer on the sacrificial layer, wherein the thickness of the target layer is 100 nm to 300 nm, to obtain a GaN epitaxial wafer.

6. The method for preparing a FP ultraviolet laser based on GaN nanoribbons according to claim 4, characterized in that: A photoresist layer with a stripe array pattern is formed on the surface of the GaN epitaxial wafer through mature industry-recognized UV lithography technology, which serves as a mask for ICP dry etching.

7. The method for preparing a FP ultraviolet laser based on GaN nanoribbons according to claim 4, characterized in that: By using ICP dry etching technology, the GaN epitaxial wafer is subjected to ICP dry etching using a photoresist with a stripe array pattern as a mask; the etching depth is 200 nm to 500 nm; and an intermediate product containing a nanobelt stripe array is obtained.

8. The method for preparing a FP ultraviolet laser based on GaN nanoribbons according to claim 4, characterized in that: The intermediate product containing the nanobelt stripe array is electrochemically stripped to corrode the heavily doped GaN sacrificial layer to obtain GaN nanobelts; the electrolyte for the electrochemical stripping is an oxalic acid solution with a concentration of 0.3 mol / L; the voltage of the electrochemical stripping is 10 to 15 V and the time is 5 to 10 min.

9. A debugging method for the GaN nanoribbon-based FP ultraviolet laser according to claim 1, characterized in that: The solubility of the KOH solution is 2 mol / L, the corrosion temperature is 80°C, and the corrosion time is 1 min to 10 min.

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