Gallium nitride laser material, method of making and use thereof
By introducing a Si-doped n-InGaN gradient insertion layer into gallium nitride laser materials and adjusting the lattice constant, the problem of low carrier recombination efficiency was solved, resulting in higher carrier injection and recombination efficiency and improved optical performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- THE 13TH RES INST OF CHINA ELECTRONICS TECH GRP CORP
- Filing Date
- 2025-07-02
- Publication Date
- 2026-06-09
Smart Images
Figure CN122178191A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of gallium nitride laser technology, and more particularly to a gallium nitride laser material, its preparation method, and its applications. Background Technology
[0002] Gallium nitride (GaN) lasers have developed rapidly and are widely used in laser displays, laser lighting, laser printing, laser measurement, and laser communication. With the continuous advancement of laser material growth technology and chip fabrication processes, the threshold current density and turn-on voltage of GaN lasers are constantly decreasing, while output power and lifetime are continuously improving, thus placing higher demands on growth materials. Currently, a key technical problem restricting the development of GaN laser materials and devices is low carrier recombination efficiency. Laser materials grown on GaN substrates using MOCVD (novel vapor-phase epitaxy) require InGaN material in both the waveguide region and the quantum well emission region. Because the lattice constant of InGaN is greater than that of GaN, a large number of defects are introduced during the epitaxial layer growth process due to lattice mismatch between InGaN and GaN materials. This generates stress, increases the absorption coefficient, and leads to a decrease in carrier recombination efficiency, adversely affecting the overall performance of the GaN laser. Summary of the Invention
[0003] To address the issue of low carrier recombination efficiency in gallium nitride (GaN) laser materials, this invention provides a GaN laser material, its fabrication method, and its applications. By introducing a Si-doped n-InGaN gradient insertion layer between a Si-doped n-AlGaN buffer layer and a Si-doped n-AlGaN lower barrier layer, the defect density of the n-InGaN waveguide layer and subsequent structures during growth is reduced, thereby improving carrier injection and recombination efficiency and enhancing the overall performance of the GaN laser.
[0004] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: In a first aspect, the present invention provides a gallium nitride laser material, the structure of which, from bottom to top, comprises: a GaN substrate, a Si-doped n-GaN buffer layer, a Si-doped n-AlGaN buffer layer, a Si-doped n-InGaN graded insertion layer, a Si-doped n-AlGaN lower barrier layer, and an InGaN lower waveguide layer. The mass content of In element in the Si-doped n-InGaN graded insertion layer gradually changes from 0-1% to 5%-10% from bottom to top.
[0005] Compared to existing technologies, the gallium nitride laser material provided by this invention introduces an In composition-gradient Si-doped n-InGaN gradient insertion layer in the early stage of GaN material growth. This provides prestress for the InGaN lower waveguide layer material grown on top, which can alleviate the stress during the growth of the waveguide region and the quantum well light-emitting region, adjust the lattice constant, and effectively block the upward extension of penetrating dislocations. This reduces the defect density during the growth of the n-type material, the InGaN lower waveguide layer, and subsequent structural materials, lowers the absorption coefficient, and improves the carrier injection and recombination efficiency. Ultimately, this achieves the goal of increasing output power and enhancing optical performance, resulting in a gallium nitride laser material with both high optical performance and crystal quality.
[0006] The InGaN lower waveguide layer is used to confine the optical field in conjunction with the quantum well. Although it has some stress modulation effect, its modulation effect is weak and insufficient to compensate for the strain effect of the entire gallium nitride laser material. This invention introduces a Si-doped n-InGaN graded insertion layer between the Si-doped n-AlGaN buffer layer and the Si-doped n-AlGaN lower barrier layer, and limits the In element content therein. This effectively enlarges the lattice, reduces lattice defects, and modulates the lattice strain. The graded In composition effectively reduces epitaxial dislocations in the upper layer, improves the crystal quality of InGaN, and has high market application value.
[0007] For example, the waveguide layer under InGaN is undoped.
[0008] Preferably, the Si doping concentration in the Si-doped n-GaN buffer layer, the Si-doped n-AlGaN buffer layer, the Si-doped n-InGaN graded insertion layer, and the Si-doped n-AlGaN lower barrier layer is independently 1×10⁻⁶. 18 cm -3 ~3×10 18 cm -3 .
[0009] Gallium nitride lasers are typically grown on n-type substrates, with n electrodes on the substrate surface. The underlying layers are undoped, preventing current from passing through.
[0010] Preferably, the mass content of Al element in the Si-doped n-AlGaN buffer layer is 1% to 6%.
[0011] This invention limits the Al content in the Si-doped n-AlGaN buffer layer to simultaneously ensure the crystal quality and high adhesion of the layer.
[0012] Preferably, the mass content of In element in the Si-doped n-InGaN graded insertion layer gradually changes from 0.5% to 1% to 6% to 8% from bottom to top.
[0013] More preferably, the mass content of In element in the Si-doped n-InGaN gradient insertion layer gradually increases from 1% to 7% from bottom to top.
[0014] Preferably, the mass content of Al element in the Si-doped n-AlGaN barrier layer is 1% to 15%.
[0015] Preferably, the mass content of In element in the InGaN lower waveguide layer is 1% to 10%.
[0016] This invention limits the In element content in the Si-doped n-InGaN graded insertion layer, which can further increase the lattice matching degree between InGaN and GaN materials in the waveguide layer.
[0017] Preferably, the thickness of the Si-doped n-GaN buffer layer is 50 nm to 500 nm.
[0018] Preferably, the thickness of the Si-doped n-AlGaN buffer layer is 1000 nm to 2000 nm.
[0019] Preferably, the thickness of the Si-doped n-InGaN gradient insertion layer is 30 nm to 200 nm.
[0020] Preferably, the thickness of the barrier layer under Si-doped n-AlGaN is 500nm~2000nm.
[0021] Preferably, the thickness of the InGaN lower waveguide layer is 50nm~200nm.
[0022] This invention, by controlling the element content and thickness of each layer, can better meet the performance design requirements of gallium nitride laser materials and further improve the overall performance of gallium nitride lasers.
[0023] Secondly, the present invention provides a method for preparing the gallium nitride laser material described above, comprising the following steps: S1. Using the MOCVD method, under a hydrogen atmosphere, a Si-doped n-GaN buffer layer and a Si-doped n-AlGaN buffer layer are sequentially grown on the surface of a GaN substrate. S2. Using a variable temperature method or by changing the In source flow rate, a Si-doped n-InGaN gradient insertion layer is grown on the surface of the Si-doped n-AlGaN buffer layer under an inert atmosphere. S3. Under a hydrogen atmosphere, a Si-doped n-AlGaN lower barrier layer is grown on the surface of the Si-doped n-InGaN gradient insertion layer; the atmosphere is then switched to an inert atmosphere, and an InGaN lower waveguide layer is grown to obtain gallium nitride laser material.
[0024] Preferably, in the MOCVD method, the Ga source includes at least one of TMGa or TEGa, the N source includes NH3, the Si source includes at least one of SiH4, Si2H6 or DETe, the Al source includes TMAl, the In source includes TMIn, and the Al source includes TMAl.
[0025] Preferably, in S1, the GaN substrate needs to be subjected to high-temperature treatment before growing the Si-doped n-GaN buffer layer on the GaN substrate surface.
[0026] More preferably, in S1, the high-temperature treatment temperature is 1000℃~1150℃, the pressure is 50mbar~300mbar, and the high-temperature treatment time is 2min~15min.
[0027] GaN substrates have a crystalline structure. Due to polishing and chemical treatments, their surfaces are relatively rough and have an oxide layer. High-temperature processing can remove oxides and impurities from the GaN substrate surface, exposing the atomic steps and facilitating subsequent structure growth. Through extensive experimentation, this invention has found that if the high-temperature processing temperature is too high, it will severely etch the GaN substrate, resulting in a rough surface; if the high-temperature processing temperature is too low, it cannot effectively remove the oxide layer from the GaN substrate surface.
[0028] Preferably, in S1, the growth temperature of the Si-doped n-GaN buffer layer is 800℃~1150℃ (more preferably 1000℃~1150℃), and the growth pressure is 50mbar~300mbar.
[0029] Preferably, in S1, the growth temperature of the Si-doped n-AlGaN buffer layer is 950℃~1150℃, and the growth pressure is 50mbar~300mbar.
[0030] For example, in S2~S3, the inert atmosphere is nitrogen.
[0031] Preferably, in S2, the growth temperature of the Si-doped n-InGaN gradient insertion layer is gradually reduced from 900℃~1000℃ to 700℃~850℃, the growth pressure is 50mbar~500mbar, and the flow rate of the In source is 200sccm~1000sccm.
[0032] More preferably, in S2, the growth temperature of the Si-doped n-InGaN gradient insertion layer is gradually reduced from 950℃~980℃ to 700℃~780℃, and the cooling rate is 1℃ / min~2℃ / min; the flow rate of the In source is 400sccm~900sccm.
[0033] Preferably, in S2, the growth temperature of the Si-doped n-InGaN gradient insertion layer is 700℃~850℃, the growth pressure is 50mbar~500mbar, and the flow rate of the In source is gradually increased from 5sccm~20sccm to 800sccm~1000sccm.
[0034] More preferably, in S2, the growth temperature of the Si-doped n-InGaN gradient insertion layer is 720℃~800℃, the growth pressure is 50mbar~500mbar, and the flow rate of the In source is gradually increased from 5sccm~15sccm to 900sccm~1000sccm.
[0035] This invention uses a variable temperature method or changes the In source flow rate to control the In element content, which is used to grow InGaN with a low composition of close to 0 to 5%~10%. The slowly changing composition can make the lattice of the material gradually larger, thereby reducing the generation of defects in the subsequent structure growth process.
[0036] Preferably, in S3, the growth temperature of the Si-doped n-AlGaN barrier layer is 950℃~1150℃, and the growth pressure is 50mbar~300mbar.
[0037] Preferably, in S3, the growth temperature of the InGaN lower waveguide layer is 700℃~950℃, and the growth pressure is 50mbar~500mbar.
[0038] This invention, by controlling the growth temperature and pressure of each layer, ensures high growth efficiency and superior crystal quality for each layer. Extensive testing revealed that excessively high growth temperatures lead to rapid decomposition of the metal compounds, resulting in low growth efficiency; excessively low growth temperatures degrade crystal quality; excessively high growth pressures increase impurities in the gallium nitride laser material, further worsening crystal quality; and excessively low growth pressures reduce raw material utilization.
[0039] Thirdly, the present invention provides a gallium nitride laser, comprising the gallium nitride laser material described above.
[0040] Preferably, the structure of the gallium nitride laser, from bottom to top, includes: a GaN substrate, a Si-doped n-GaN buffer layer, a Si-doped n-AlGaN buffer layer, a Si-doped n-InGaN graded insertion layer, a Si-doped n-AlGaN lower barrier layer, an InGaN lower waveguide layer, an InGaN quantum well layer, an InGaN upper waveguide layer, an AlGaN electron blocking layer, an AlGaN upper barrier layer, and a GaN ohmic contact layer. Attached Figure Description
[0041] Figure 1 This is a schematic diagram of the structure of the gallium nitride laser material in an embodiment of the present invention; in the figure, 1 represents the GaN substrate, 2 represents the Si-doped n-GaN buffer layer, 3 represents the Si-doped n-AlGaN buffer layer, 4 represents the Si-doped n-InGaN gradient insertion layer, 5 represents the Si-doped n-AlGaN lower barrier layer, and 6 represents the InGaN lower waveguide layer. Detailed Implementation
[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0043] In this invention, all materials not otherwise specified are commercially available products.
[0044] Example 1 This embodiment provides a gallium nitride laser material (see...) Figure 1 Its structure, from bottom to top, includes: a GaN substrate 1, a Si-doped n-GaN buffer layer 2, a Si-doped n-AlGaN buffer layer 3, a Si-doped n-InGaN graded insertion layer 4, a Si-doped n-AlGaN lower barrier layer 5, and an InGaN lower waveguide layer 6. In the Si-doped n-InGaN graded insertion layer 4, the mass content of In gradually increases from 1% to 7% from bottom to top; in the Si-doped n-AlGaN buffer layer 3, the mass content of Al is 4%; in the Si-doped n-AlGaN lower barrier layer 5, the mass content of Al is 8%; and in the InGaN lower waveguide layer 6, the mass content of In is 5%. The Si doping concentration in Si-doped n-GaN buffer layer 2, Si-doped n-AlGaN buffer layer 3, Si-doped n-InGaN graded insertion layer 4, and Si-doped n-AlGaN lower barrier layer 5 is all 2 × 10⁻⁶. 18 cm -3 InGaN waveguide layer 6 is undoped; The thickness of the Si-doped n-GaN buffer layer 2 is 300 nm, the thickness of the Si-doped n-AlGaN buffer layer 3 is 1500 nm, the thickness of the Si-doped n-InGaN gradient insertion layer 4 is 120 nm, the thickness of the Si-doped n-AlGaN lower barrier layer 5 is 1200 nm, and the thickness of the InGaN lower waveguide layer 6 is 120 nm.
[0045] The preparation method of the above-mentioned gallium nitride laser material includes the following steps: S100. Using the MOCVD method, GaN substrate 1 is placed in the reaction chamber, heated to 1100℃ in a hydrogen atmosphere, and then the pressure is reduced to 180mbar to perform high-temperature treatment on GaN substrate 1. After 8 minutes, atomic steps are formed.
[0046] S200. Under a hydrogen atmosphere, maintain the temperature and pressure of the MOCVD equipment and grow a Si-doped n-GaN buffer layer 2 on the surface of GaN substrate 1; the Ga source is TMGa, the N source is NH3, and the Si source is SiH4.
[0047] S300, maintaining the pressure of the MOCVD equipment, grow a Si-doped n-AlGaN buffer layer 3 on the surface of the Si-doped n-GaN buffer layer 2 at 1050℃; the Al source is TMAl, the Ga source is TMGa, the N source is NH3, and the Si source is SiH4.
[0048] The S400 MOCVD equipment growth was interrupted, the system carrier gas was converted to nitrogen, the growth pressure was 300 mbar, the In source flow rate was 800 sccm, and a variable temperature method was used to grow a Si-doped n-InGaN gradient insertion layer 4 on the surface of the Si-doped n-AlGaN buffer layer 3. The temperature of the MOCVD equipment was adjusted to gradually decrease from 950℃ to 750℃ and then stop the growth, thereby controlling the gradient of the In composition; the In source was TMI, the Ga source was TEGa, the N source was NH3, and the Si source was SiH4.
[0049] The S500 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to hydrogen. A Si-doped n-AlGaN barrier layer 5 was grown on the surface of the Si-doped n-InGaN gradient insertion layer 4 at 1050℃ and 220mbar. The Al source was TMAl, the Ga source was TMGa, the N source was NH3, and the Si source was SiH4.
[0050] The S600 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to nitrogen. An InGaN waveguide layer 6 was grown on the surface of the Si-doped n-AlGaN barrier layer 5 at 820℃ and 300mbar. The In source was TMI, the Ga source was TEGa, and the N source was NH3, thus obtaining gallium nitride laser material.
[0051] Example 2 This embodiment provides a gallium nitride laser material (see...) Figure 1 Its structure, from bottom to top, includes: a GaN substrate 1, a Si-doped n-GaN buffer layer 2, a Si-doped n-AlGaN buffer layer 3, a Si-doped n-InGaN graded insertion layer 4, a Si-doped n-AlGaN lower barrier layer 5, and an InGaN lower waveguide layer 6. In the Si-doped n-InGaN graded insertion layer 4, the mass content of In gradually increases from 0.1% to 5.2% from bottom to top; in the Si-doped n-AlGaN buffer layer 3, the mass content of Al is 3%; in the Si-doped n-AlGaN lower barrier layer 5, the mass content of Al is 10%; and in the InGaN lower waveguide layer 6, the mass content of In is 1%. The Si doping concentration in Si-doped n-GaN buffer layer 2, Si-doped n-AlGaN buffer layer 3, Si-doped n-InGaN graded insertion layer 4, and Si-doped n-AlGaN lower barrier layer 5 is 3 × 10⁻⁶. 18 cm -3 InGaN waveguide layer 6 is undoped; The thickness of the Si-doped n-GaN buffer layer 2 is 500 nm, the thickness of the Si-doped n-AlGaN buffer layer 3 is 2000 nm, the thickness of the Si-doped n-InGaN graded insertion layer 4 is 200 nm, the thickness of the Si-doped n-AlGaN lower barrier layer 5 is 2000 nm, and the thickness of the InGaN lower waveguide layer 6 is 200 nm.
[0052] The preparation method of the above-mentioned gallium nitride laser material includes the following steps: S100. Using the MOCVD method, GaN substrate 1 is placed in the reaction chamber, heated to 1050℃ in a hydrogen atmosphere, and then vacuumed to 150mbar to perform high-temperature treatment on GaN substrate 1. After 10 minutes, atomic steps are formed.
[0053] S200. Under a hydrogen atmosphere, maintain the temperature and pressure of the MOCVD equipment and grow a Si-doped n-GaN buffer layer 2 on the surface of GaN substrate 1; the Ga source is TMGa, the N source is NH3, and the Si source is SiH4.
[0054] S300, maintaining the pressure of the MOCVD equipment, grow a Si-doped n-AlGaN buffer layer 3 on the surface of the Si-doped n-GaN buffer layer 2 at 1000℃; the Al source is TMAl, the Ga source is TMGa, the N source is NH3, and the Si source is SiH4.
[0055] The S400 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to nitrogen. At 750℃ and 200mbar, a Si-doped n-InGaN gradient insertion layer 4 was grown on the surface of the Si-doped n-AlGaN buffer layer 3 by changing the In source flow rate. The In source flow rate was adjusted from 10 sccm to 800 sccm and then growth was stopped to control the gradient of the In composition. The In source was TMI, the Ga source was TEGa, the N source was NH3, and the Si source was SiH4.
[0056] The S500 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to hydrogen. A Si-doped n-AlGaN barrier layer 5 was grown on the surface of the Si-doped n-InGaN gradient insertion layer 4 at 1000℃ and 200mbar. The Al source was TMAl, the Ga source was TMGa, the N source was NH3, and the Si source was SiH4.
[0057] The S600 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to nitrogen. An InGaN waveguide layer 6 was grown on the surface of the Si-doped n-AlGaN barrier layer 5 at 800℃ and 200mbar. The In source was TMI, the Ga source was TEGa, and the N source was NH3, thus obtaining gallium nitride laser material.
[0058] Example 3 This embodiment provides a gallium nitride laser material (see...) Figure 1 Its structure, from bottom to top, includes: a GaN substrate 1, a Si-doped n-GaN buffer layer 2, a Si-doped n-AlGaN buffer layer 3, a Si-doped n-InGaN graded insertion layer 4, a Si-doped n-AlGaN lower barrier layer 5, and an InGaN lower waveguide layer 6. The mass content of In in the Si-doped n-InGaN graded insertion layer 4 gradually increases from 0.5% to 9.8% from bottom to top; the mass content of Al in the Si-doped n-AlGaN buffer layer 3 is 6%; the mass content of Al in the Si-doped n-AlGaN lower barrier layer 5 is 14.6%; and the mass content of In in the InGaN lower waveguide layer 6 is 9.7%. The Si doping concentration in Si-doped n-GaN buffer layer 2, Si-doped n-AlGaN buffer layer 3, Si-doped n-InGaN graded insertion layer 4, and Si-doped n-AlGaN lower barrier layer 5 is 1×10⁻⁶. 18 cm -3 InGaN waveguide layer 6 is undoped; The thickness of the Si-doped n-GaN buffer layer 2 is 50 nm, the thickness of the Si-doped n-AlGaN buffer layer 3 is 1000 nm, the thickness of the Si-doped n-InGaN gradient insertion layer 4 is 30 nm, the thickness of the Si-doped n-AlGaN lower barrier layer 5 is 500 nm, and the thickness of the InGaN lower waveguide layer 6 is 50 nm.
[0059] The preparation method of the above-mentioned gallium nitride laser material includes the following steps: S100. Using the MOCVD method, GaN substrate 1 is placed in the reaction chamber, heated to 1150℃ in a hydrogen atmosphere, and then vacuumed to 300mbar to perform high-temperature treatment on GaN substrate 1. After 2 minutes, atomic steps are formed.
[0060] S200. Under a hydrogen atmosphere, maintain the temperature and pressure of the MOCVD equipment and grow a Si-doped n-GaN buffer layer 2 on the surface of GaN substrate 1; the Ga source is TMGa, the N source is NH3, and the Si source is SiH4.
[0061] S300, maintaining the pressure of the MOCVD equipment, grow a Si-doped n-AlGaN buffer layer 3 on the surface of the Si-doped n-GaN buffer layer 2 at 1150℃; the Al source is TMAl, the Ga source is TMGa, the N source is NH3, and the Si source is SiH4.
[0062] The S400 MOCVD equipment growth was interrupted, the system carrier gas was converted to nitrogen, the growth pressure was 500 mbar, the In source flow rate was 600 sccm, and a variable temperature method was used to grow a Si-doped n-InGaN gradient insertion layer 4 on the surface of the Si-doped n-AlGaN buffer layer 3. The temperature of the MOCVD equipment was adjusted to gradually decrease from 1100℃ to 820℃ and then the growth was stopped, thereby controlling the gradient of the In composition; the In source was TMI, the Ga source was TEGa, the N source was NH3, and the Si source was SiH4.
[0063] The S500 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to hydrogen. A Si-doped n-AlGaN barrier layer 5 was grown on the surface of the Si-doped n-InGaN gradient insertion layer 4 at 1150℃ and 300mbar. The Al source was TMAl, the Ga source was TMGa, the N source was NH3, and the Si source was SiH4.
[0064] The S600 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to nitrogen. An InGaN waveguide layer 6 was grown on the surface of the Si-doped n-AlGaN barrier layer 5 at 950℃ and 500mbar. The In source was TMI, the Ga source was TEGa, and the N source was NH3, thus obtaining gallium nitride laser material.
[0065] Example 4 This embodiment provides a gallium nitride laser material (see...) Figure 1 Its structure, from bottom to top, includes: a GaN substrate 1, a Si-doped n-GaN buffer layer 2, a Si-doped n-AlGaN buffer layer 3, a Si-doped n-InGaN graded insertion layer 4, a Si-doped n-AlGaN lower barrier layer 5, and an InGaN lower waveguide layer 6. In the Si-doped n-InGaN graded insertion layer 4, the mass content of In element gradually increases from 1% to 8% from bottom to top; in the Si-doped n-AlGaN buffer layer 3, the mass content of Al element is 1%; in the Si-doped n-AlGaN lower barrier layer 5, the mass content of Al element is 1%; and in the InGaN lower waveguide layer 6, the mass content of In element is 6%. The Si doping concentrations in Si-doped n-GaN buffer layer 2, Si-doped n-AlGaN buffer layer 3, Si-doped n-InGaN graded insertion layer 4, and Si-doped n-AlGaN lower barrier layer 5 are 2.1 × 10⁻⁶, respectively. 18 cm -3 1.7×10 18 cm -3 1.9×10 18 cm -3 and 2.3×10 18 cm -3 InGaN waveguide layer 6 is undoped; The thickness of the Si-doped n-GaN buffer layer 2 is 200 nm, the thickness of the Si-doped n-AlGaN buffer layer 3 is 1200 nm, the thickness of the Si-doped n-InGaN gradient insertion layer 4 is 100 nm, the thickness of the Si-doped n-AlGaN lower barrier layer 5 is 1500 nm, and the thickness of the InGaN lower waveguide layer 6 is 100 nm.
[0066] The preparation method of the above-mentioned gallium nitride laser material includes the following steps: S100. Using the MOCVD method, GaN substrate 1 is placed in the reaction chamber, heated to 1000℃ in a hydrogen atmosphere, and then vacuumed to 50mbar to perform high-temperature treatment on GaN substrate 1. After 15 minutes, atomic steps are formed.
[0067] S200. Under a hydrogen atmosphere, maintain the temperature and pressure of the MOCVD equipment and grow a Si-doped n-GaN buffer layer 2 on the surface of GaN substrate 1; the Ga source is TMGa, the N source is NH3, and the Si source is SiH4.
[0068] S300, maintaining the pressure of the MOCVD equipment, grow a Si-doped n-AlGaN buffer layer 3 on the surface of the Si-doped n-GaN buffer layer 2 at 950℃; the Al source is TMAl, the Ga source is TMGa, the N source is NH3, and the Si source is SiH4.
[0069] The S400 MOCVD equipment growth was interrupted, the system carrier gas was converted to nitrogen, the growth pressure was 50 mbar, the In source flow rate was 440 sccm, and a variable temperature method was used to grow a Si-doped n-InGaN gradient insertion layer 4 on the surface of the Si-doped n-AlGaN buffer layer 3. The temperature of the MOCVD equipment was adjusted to gradually decrease from 950℃ to 780℃ and then the growth was stopped, thereby controlling the gradient of the In composition; the In source was TMI, the Ga source was TEGa, the N source was NH3, and the Si source was SiH4.
[0070] The S500 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to hydrogen. A Si-doped n-AlGaN barrier layer 5 was grown on the surface of the Si-doped n-InGaN gradient insertion layer 4 at 950℃ and 50mbar. The Al source was TMAl, the Ga source was TMGa, the N source was NH3, and the Si source was SiH4.
[0071] The S600 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to nitrogen. An InGaN waveguide layer 6 was grown on the surface of the Si-doped n-AlGaN barrier layer 5 at 700℃ and 50mbar. The In source was TMI, the Ga source was TEGa, and the N source was NH3, thus obtaining gallium nitride laser material.
[0072] Comparative Example 1 This comparative example provides a gallium nitride laser material, the structure of which is similar to that of Example 1, except that it does not include the Si-doped n-InGaN graded insertion layer 4. The rest of the design is the same as that of Example 1, and will not be described again.
[0073] The preparation method of the gallium nitride laser material described above is the same as that in Example 1, except that step S400 is omitted. The remaining steps and conditions are the same as in Example 1 and will not be repeated here.
[0074] Comparative Example 2 This comparative example provides a gallium nitride laser material, the structure of which is similar to that of Example 1, except that the Si-doped n-InGaN gradient insertion layer 4 is replaced with a Si-doped n-InGaN insertion layer with an In content of 7% by mass. The rest of the design is the same as in Example 1 and will not be described again.
[0075] The preparation method of the above-mentioned gallium nitride laser material includes the following steps: S100~S300 are the same as S100~S300 in Example 1, and will not be described again.
[0076] The S400 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to nitrogen. A Si-doped n-InGaN insertion layer was grown on the surface of the Si-doped n-AlGaN buffer layer 3 at 750℃ and 300mbar. The In source was TMI, the Ga source was TEGa, the N source was NH3, and the Si source was SiH4.
[0077] The S500 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to hydrogen. A Si-doped n-AlGaN barrier layer 5 was grown on the surface of the Si-doped n-InGaN insertion layer at 1050℃ and 220mbar. The Al source was TMAl, the Ga source was TMGa, the N source was NH3, and the Si source was SiH4.
[0078] S600 is the same as S600 in Example 1, and will not be described again.
[0079] Comparative Example 3 This comparative example provides a gallium nitride laser material, the structure of which is similar to that of Example 1, except that the Si-doped n-InGaN gradient insertion layer 4 is replaced with a Si-doped n-InGaN insertion layer with an In element mass content of 1%. The rest of the design is the same as that of Example 1, and will not be described again.
[0080] The preparation method of the above-mentioned gallium nitride laser material includes the following steps: S100~S300 are the same as S100~S300 in Example 1, and will not be described again.
[0081] The S400 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to nitrogen. A Si-doped n-InGaN insertion layer was grown on the surface of the Si-doped n-AlGaN buffer layer 3 at 950℃ and 300mbar. The In source was TMIn, the Ga source was TEGa, the N source was NH3, and the Si source was SiH4.
[0082] The S500 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to hydrogen. A Si-doped n-AlGaN barrier layer 5 was grown on the surface of the Si-doped n-InGaN insertion layer at 1050℃ and 220mbar. The Al source was TMAl, the Ga source was TMGa, the N source was NH3, and the Si source was SiH4.
[0083] S600 is the same as S600 in Example 1, and will not be described again.
[0084] Comparative Example 4 This comparative example provides a gallium nitride laser material with a structure similar to that of Example 1, except that the positions of the Si-doped n-InGaN graded insertion layer 4 and the Si-doped n-AlGaN buffer layer 3 are replaced. The rest of the design is the same as in Example 1 and will not be described again.
[0085] The preparation method of the above-mentioned gallium nitride laser material includes the following steps: S100~S200 are the same as S100~S200 in Example 1, and will not be described again.
[0086] The S300 MOCVD equipment growth was interrupted, the system carrier gas was converted to nitrogen, the growth pressure was 300 mbar, the In source flow rate was 800 sccm, and a Si-doped n-InGaN gradient insertion layer was grown on the surface of the Si-doped n-GaN buffer layer 2 using a variable temperature method. The temperature of the MOCVD equipment was adjusted to gradually decrease from 950℃ to 750℃ and then stop the growth, thereby controlling the gradient of the In composition. The In source was TMI, the Ga source was TEGa, the N source was NH3, and the Si source was SiH4.
[0087] The S400 and MOCVD equipment growth was interrupted, and the system carrier gas was converted to hydrogen. A Si-doped n-AlGaN buffer layer 3 was grown on the surface of the Si-doped n-InGaN gradient insertion layer 4 at 1050℃ and 220mbar. The Al source was TMAl, the Ga source was TMGa, the N source was NH3, and the Si source was SiH4.
[0088] S500. Under a hydrogen atmosphere, maintain the temperature and pressure of the MOCVD equipment and grow a Si-doped n-AlGaN lower barrier layer 5 on the surface of the Si-doped n-AlGaN buffer layer 3; the Al source is TMAl, the Ga source is TMGa, the N source is NH3, and the Si source is SiH4.
[0089] S600 is the same as S600 in Example 1, and will not be described again.
[0090] Comparative Example 5 This comparative example provides a gallium nitride laser material, the structure of which is similar to that of Example 1, except that the positions of the Si-doped n-InGaN graded insertion layer 4 and the Si-doped n-AlGaN lower barrier layer 5 are replaced. The rest of the design is the same as in Example 1 and will not be described again.
[0091] The preparation method of the above-mentioned gallium nitride laser material includes the following steps: S100~S300 are the same as S100~S300 in Example 1, and will not be described again.
[0092] S400. Under a hydrogen atmosphere, maintain the temperature and pressure of the MOCVD equipment and grow a Si-doped n-AlGaN lower barrier layer 5 on the surface of the Si-doped n-AlGaN buffer layer 3; the Al source is TMAl, the Ga source is TMGa, the N source is NH3, and the Si source is SiH4.
[0093] The S500 MOCVD equipment growth was interrupted, the system carrier gas was converted to nitrogen, the growth pressure was 300 mbar, the In source flow rate was 800 sccm, and a variable temperature method was used to grow a Si-doped n-InGaN gradient insertion layer 4 on the surface of the Si-doped n-AlGaN barrier layer 5. The temperature of the MOCVD equipment was adjusted to gradually decrease from 950℃ to 750℃ and then stop the growth, thereby controlling the gradient of the In composition. The In source was TMI, the Ga source was TEGa, the N source was NH3, and the Si source was SiH4.
[0094] S600, maintaining the pressure of the MOCVD equipment, grow an InGaN lower waveguide layer 6 on the surface of the Si-doped n-InGaN gradient insertion layer 4; the In source is TMIn, the Ga source is TEGa, and the N source is NH3, to obtain gallium nitride laser material.
[0095] Verification test X-ray diffraction tests were performed on the (002) and (102) crystal planes of the gallium nitride laser materials provided in Examples 1-4 and Comparative Examples 1-5, respectively. The obtained half-width value can reflect the magnitude of the defect density. The larger the half-width, the higher the defect density. This method is a general method for testing GaN-based epitaxy.
[0096] After the test was completed, the gallium nitride laser materials provided in Examples 1-4 and Comparative Examples 1-5 were fabricated into GaN laser chips. The threshold and power at 2A current of each GaN laser chip were tested to reflect the differences in performance parameters of different fabrication methods.
[0097] The test results of the above verification experiments are shown in Table 1.
[0098] Table 1. Performance test results of gallium nitride laser materials in the examples and comparative examples.
[0099] From the test results above, we can conclude that: In Examples 1-4, Si-doped n-InGaN insertion layers with gradient In composition were used. Their XRD half-width was significantly lower than that of all comparative examples, indicating that the structure effectively suppressed dislocation propagation and had better crystal quality.
[0100] Compared to Comparative Example 1 (completely without intercalation), the threshold current of the embodiment is reduced by an average of about 35%, and the output power is increased by more than 40%, reflecting a significant improvement in carrier recombination efficiency and light extraction efficiency.
[0101] Although InGaN intercalation was introduced in Comparative Examples 2 and 3, a gradient structure was not adopted, and the defect concentration caused by lattice abrupt change still existed, resulting in limited performance improvement.
[0102] Although Comparative Examples 4 and 5 maintain a gradient structure, the placement of the insertion layer is unreasonable, which cannot effectively alleviate the stress of the subsequent waveguide layer and still leads to dislocation propagation.
[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A gallium nitride laser material, characterized in that, Its structure, from bottom to top, includes: GaN substrate, Si-doped n-GaN buffer layer, Si-doped n-AlGaN buffer layer, Si-doped n-InGaN graded insertion layer, Si-doped n-AlGaN lower barrier layer and InGaN lower waveguide layer; The mass content of In element in the Si-doped n-InGaN graded insertion layer gradually changes from 0-1% to 5%-10% from bottom to top.
2. The gallium nitride laser material as described in claim 1, characterized in that, The mass content of Al element in the Si-doped n-AlGaN buffer layer is 1%~6%; The mass content of Al in the Si-doped n-AlGaN barrier layer is 1%~15%; The mass content of In element in the InGaN lower waveguide layer is 1%~10%.
3. The gallium nitride laser material as described in claim 1, characterized in that, The thickness of the Si-doped n-GaN buffer layer is 50 nm to 500 nm; The thickness of the Si-doped n-AlGaN buffer layer is 1000 nm to 2000 nm; The thickness of the Si-doped n-InGaN graded insertion layer is 30 nm to 200 nm. The thickness of the barrier layer under Si-doped n-AlGaN is 500 nm to 2000 nm; The thickness of the InGaN underwaveguide layer is 50nm~200nm.
4. The gallium nitride laser material as described in claim 1, characterized in that, The Si doping concentration in the Si-doped n-GaN buffer layer, Si-doped n-AlGaN buffer layer, Si-doped n-InGaN graded insertion layer, and Si-doped n-AlGaN lower barrier layer is independently 1×10⁻⁶. 18 cm -3 ~3×10 18 cm -3 .
5. The method for preparing gallium nitride laser material according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Using the MOCVD method, under a hydrogen atmosphere, a Si-doped n-GaN buffer layer and a Si-doped n-AlGaN buffer layer are sequentially grown on the surface of a GaN substrate. S2. Using a variable temperature method or by changing the In source flow rate, a Si-doped n-InGaN gradient insertion layer is grown on the surface of the Si-doped n-AlGaN buffer layer under an inert atmosphere. S3. Under a hydrogen atmosphere, a Si-doped n-AlGaN lower barrier layer is grown on the surface of the Si-doped n-InGaN gradient insertion layer; the atmosphere is then switched to an inert atmosphere, and an InGaN lower waveguide layer is grown to obtain gallium nitride laser material.
6. The method for preparing gallium nitride laser material as described in claim 5, characterized in that, In S2, the growth temperature of the Si-doped n-InGaN graded insertion layer is gradually reduced from 900℃~1000℃ to 700℃~850℃, the growth pressure is 50mbar~500mbar, and the In source flow rate is 200sccm~1000sccm; or In S2, the growth temperature of the Si-doped n-InGaN gradient insertion layer is 700℃~850℃, the growth pressure is 50mbar~500mbar, and the flow rate of the In source is gradually increased from 5sccm~20sccm to 800sccm~1000sccm.
7. The method for preparing gallium nitride laser material as described in claim 5, characterized in that, In S1, before growing a Si-doped n-GaN buffer layer on the surface of the GaN substrate, the GaN substrate needs to be subjected to high-temperature treatment.
8. The method for preparing gallium nitride laser material as described in claim 5, characterized in that, In S1, the high-temperature treatment temperature is 1000℃~1150℃, the pressure is 50mbar~300mbar, and the high-temperature treatment time is 2min~15min; In S1, the growth temperature of the Si-doped n-GaN buffer layer is 800℃~1150℃, and the growth pressure is 50mbar~300mbar. In S1, the growth temperature of the Si-doped n-AlGaN buffer layer is 950℃~1150℃, and the growth pressure is 50mbar~300mbar. In S3, the growth temperature of the Si-doped n-AlGaN barrier layer is 950℃~1150℃, and the growth pressure is 50mbar~300mbar. In S3, the growth temperature of the InGaN lower waveguide layer is 700℃~950℃, and the growth pressure is 50mbar~500mbar.
9. A gallium nitride laser, characterized in that, This includes the gallium nitride laser material according to any one of claims 1 to 4, or the gallium nitride laser material prepared by the method according to any one of claims 5 to 8.
10. The gallium nitride laser as claimed in claim 9, characterized in that, The structure of the gallium nitride laser, from bottom to top, includes: a GaN substrate, a Si-doped n-GaN buffer layer, a Si-doped n-AlGaN buffer layer, a Si-doped n-InGaN graded insertion layer, a Si-doped n-AlGaN lower barrier layer, an InGaN lower waveguide layer, an InGaN quantum well layer, an InGaN upper waveguide layer, an AlGaN electron blocking layer, an AlGaN upper barrier layer, and a GaN ohmic contact layer.