Preparation Method of InGaN Waveguide Layer and Semiconductor Laser

Abstract

The present application discloses a preparation method of an InGaN waveguide layer and a semiconductor laser, relating to the technical field of semiconductor optoelectronic devices. The preparation method includes introducing hydrogen, nitrogen, ammonia and a metal source into a reaction chamber, reacting for a first preset time, and the first partial pressure of hydrogen is any value from 50% to 65%; controlling the second partial pressure of hydrogen to be any value from 40% to 50%, and continuing to react for a second preset time; controlling the third partial pressure of hydrogen to be any value from 50% to 65%, and reacting for a third preset time to obtain an InGaN waveguide layer; wherein, the V / III ratio of ammonia to the metal source is any value from 500 to 1500:1, so as to prepare an InGaN waveguide layer with a thickness of any value from 200 nm to 320 nm and an In content of any value from 6% to 11%, while ensuring that the InGaN waveguide layer has a low defect density and a high crystal growth quality.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor optoelectronic devices, and in particular to a method for preparing an InGaN waveguide layer and a semiconductor laser. Background Art

[0002] GaN-based lasers have the characteristics of good directionality, high brightness, pure color, and high efficiency under high current injection. They are high-purity and high-brightness light sources. Their optical power density is 4 orders of magnitude higher than that of LEDs. They have irreplaceable and huge application prospects in the fields of laser lighting, laser display, laser direct writing lithography, underwater blue light communication, and high-power metal processing. In GaN-based semiconductor blue light laser devices, InGaN material is the core key layer as the waveguide layer. However, in InGaN materials, when the In component is greater than 6%, as the thickness of the InGaN material increases, phase separation is very likely to occur. For example, when the thickness of the InGaN material is greater than 200nm, component modulation will occur, and chemical potential and stress will compete with each other. The increase in phase separation will increase the stress of the grown InGaN film, causing problems such as uneven In component.

[0003] In the prior art, the growth temperature of the InGaN waveguide layer is usually controlled under low temperature conditions, and low flow or zero hydrogen is introduced to reduce the influence of hydrogen on In incorporation. However, this preparation method often cannot achieve high thickness, high In content and high growth quality of the InGaN waveguide layer, resulting in deep energy level defects and poor crystal quality, which seriously affects the photoelectric conversion efficiency and device reliability of semiconductor laser devices. Summary of the invention

[0004] An object of the first aspect of the present invention is to provide a method for preparing an InGaN waveguide layer, so as to solve the technical problem in the prior art that a high In component InGaN waveguide layer with a thickness greater than 200 nm is prone to phase separation.

[0005] Another object of the first aspect of the present invention is to ensure the composition uniformity and crystalline integrity of the InGaN thick film.

[0006] The second aspect of the present invention aims to provide a semiconductor laser, comprising an InGaN waveguide layer prepared by any of the preparation methods described above.

[0007] According to the purpose of the first aspect of the present invention, the present invention provides a method for preparing an InGaN waveguide layer, wherein the InGaN waveguide layer is used for preparing a blue laser, and the thickness of the InGaN waveguide layer is any value between 200nm and 320nm, and the In content is any value between 6% and 11%, and the preparation method comprises:

[0008] Hydrogen, nitrogen, ammonia, and a metal source are introduced into the reaction chamber and reacted for a first preset time, and the first partial pressure of the hydrogen is any value between 50% and 65%;

[0009] Control the second partial pressure of the hydrogen to be any value between 40% and 50%, and continue the reaction for a second preset time;

[0010] Control the third partial pressure of the hydrogen to be any value between 50% and 65%, and react for a third preset time to obtain the InGaN waveguide layer;

[0011] Among them, the V / III ratio of the ammonia to the metal source is any value between 500 and 1500:1, the growth rate ratio of the InGaN waveguide layer in the first preset time to the second preset time is any value between 1.5 and 2.5, the reaction temperature in the first preset time is lower than that in the second preset time and the temperature difference is any value between 20°C and 50°C, the metal source is a gallium source and an indium source, the flow rate of the indium source in the second preset time is any value between 70 sccm and 150 sccm, the flow rate ratio of the indium source in the first preset time to the second preset time is any value between 1.5 and 2.0, the growth rate, reaction temperature, and the flow rate of the indium source in the third preset time are the same as those in the first preset time, and the flow rate of the ammonia is any value between 15 slm and 40 slm.

[0012] Optionally, the first preset time is any value between 25 s and 35 s, and the third preset time is the same as the first preset time.

[0013] Optionally, the flow rate ratio of the gallium source in the first preset time to the second preset time is any value between 1.5 and 2.5, and the flow rate of the gallium source in the third preset time is the same as that in the first preset time.

[0014] Optionally, the flow rate of the gallium source in the second preset time is any value between 50 sccm and 100 sccm.

[0015] Optionally, the growth rate of the InGaN waveguide layer in the second preset time is any value between 0.04 μm / h and 0.15 μm / h.

[0016] Optionally, the V / III ratio of the ammonia to the metal source is any value between 1000 and 1300:1.

[0017] Optionally, the reaction temperature in the second preset time is any value between 700°C and 900°C.

[0018] Optionally, the flow rate of the nitrogen gas is any value between 15slm and 25slm, and the flow rate of the hydrogen gas is any value between 10slm and 40slm.

[0019] Optionally, the gallium source is triethylgallium, and the indium source is trimethylindium.

[0020] According to the object of the second aspect of the present invention, the present invention further provides a semiconductor laser, comprising an InGaN waveguide layer prepared by any of the preparation methods described above.

[0021] The present invention achieves coordinated optimization of multiple key process parameters by segmentally regulating the hydrogen partial pressure, reaction temperature, metal source flow rate and growth rate, and by coordinated regulation of the V / III ratio and ammonia flow rate, thereby jointly ensuring high-quality epitaxial growth of the InGaN waveguide layer with a thickness of 200nm-320nm and an In content of 6%-11%, while ensuring the crystal quality and component uniformity of the InGaN waveguide layer, providing an excellent optical waveguide performance and device reliability foundation for blue lasers.

[0022] Furthermore, the present invention precisely controls the growth time of each stage and keeps the time of the high hydrogen partial pressure stage consistent, that is, the reaction time of the first stage and the third stage are consistent, which helps to achieve the consistency and flatness of the growth interface of the InGaN waveguide layer and reduce the generation of surface roughness and hole defects. At the same time, the second stage provides sufficient crystal growth time within the same time scale, which is beneficial to uniform lattice epitaxy and stable incorporation of In components, thereby ensuring the component uniformity and crystal integrity of the InGaN thick film.

[0023] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0025] Figure 1 is a schematic flow chart of a method for preparing an InGaN waveguide layer according to an embodiment of the present invention;

[0026] Figure 2 is a schematic structural diagram of a semiconductor laser according to an embodiment of the present invention;

[0027] Figure 3is the AFM image of the InGaN waveguide layer obtained according to Embodiment 1 of the present invention;

[0028] Figure 4 is the AFM image of the InGaN waveguide layer obtained according to Comparative Example 1 of the present invention;

[0029] Figure 5 is the AFM image of the InGaN waveguide layer obtained according to Comparative Example 2 of the present invention;

[0030] Figure 6 is the AFM image of the InGaN waveguide layer obtained according to Comparative Example 3 of the present invention;

[0031] Figure 7 is the AFM image of the InGaN waveguide layer obtained according to Comparative Example 4 of the present invention;

[0032] Figure 8 is the AFM image of the InGaN waveguide layer obtained according to Comparative Example 5 of the present invention;

[0033] Figure 9 is the AFM image of the semiconductor laser epitaxial wafer according to an embodiment of the present invention.

[0034] Reference numerals:

[0035] 100 - semiconductor laser, 10 - substrate, 20 - lower confinement layer, 30 - lower waveguide layer, 40 - multi - quantum well light - emitting layer, 50 - upper waveguide layer, 60 - electron blocking layer, 70 - upper confinement layer, 80 - contact layer. Detailed embodiments

[0036] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention, but do not limit the scope of the present invention.

[0037] To make the above - mentioned objects, features, and advantages of the present application more obvious and understandable, the following combines the drawings to describe in detail the specific embodiments of the present application. It can be understood that the specific embodiments described herein are only used to explain the present application, rather than limiting the present application. Additionally, it should be noted that for the convenience of description, only the parts related to the present application are shown in the drawings, rather than all the structures. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0038] The term "comprising" and "having" in this application, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include steps or units not listed, or may optionally further include other steps or units inherent to these processes, methods, products, or devices.

[0039] Reference to "an embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0040] Figure 1 is a schematic flowchart of a method for preparing an InGaN waveguide layer according to an embodiment of the present invention.

[0041] The present invention provides a method for preparing an InGaN waveguide layer, which is used for the preparation of a blue laser, and the thickness of the InGaN waveguide layer is any value in the range of 200 nm - 320 nm, and the In content is any value in the range of 6% - 11%. That is, the thickness of the InGaN waveguide layer obtained by the method for preparing an InGaN waveguide layer for a blue laser in the present invention can be 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, or 320 nm, or any other value in the range of 200 nm - 320 nm, and the In content can be 6%, 7%, 8%, 9%, 10%, or 11%, or any other value in the range of 6% - 11%.

[0042] It should be noted that when the In component of the InGaN waveguide layer in a blue laser is greater than 5% and the thickness is greater than 200 nm, phase separation is likely to occur, resulting in a component modulation phenomenon, which affects the photoelectric conversion efficiency and device reliability of the blue laser. It is impossible to simultaneously ensure a high In component content and a large thickness when preparing the same InGaN waveguide layer. That is, those skilled in the art can only adjust one or two parameters to achieve a higher In component content or a thickness greater than 200 nm of the InGaN waveguide layer. Moreover, more hole defects will be formed on the surface of the prepared InGaN waveguide layer, and the defects will form non-radiative recombination centers, becoming the path for leakage current transport, reducing the effective carrier concentration and the output optical power. At the same time, the defects will enter the laser emission region of the chip through lattice dislocations, causing device failure.

[0043] The present invention relates to the combined setting of multiple key growth parameters, including the gradient control of hydrogen partial pressure at different growth stages, the range limitation of V / III ratio, the adjustment of temperature difference, the setting of growth rate ratio, and the regulation of indium source flow rate and its ratio between stages. Moreover, there is a high degree of coupling among multiple parameters, and they affect the growth interface stability, In incorporation behavior, and composition uniformity with each other. It is impossible to obtain ideal results through the optimization of a single variable. Especially for problems such as phase separation, stress accumulation, and composition modulation that are prone to occur under high In composition conditions in InGaN thick films, the present invention realizes the dynamic coordination of multiple variables through the construction of a refined process window.

[0044] As Figure 1 shown, the method for preparing an InGaN waveguide layer includes:

[0045] Step S100: Introduce hydrogen, nitrogen, ammonia, and a metal source into the reaction chamber and react for a first preset time. The first partial pressure of hydrogen is any value within 50% - 65%;

[0046] Step S200: Control the second partial pressure of hydrogen to be any value within 40% - 50% and continue to react for a second preset time;

[0047] Step S300: Control the third partial pressure of hydrogen to be any value within 50% - 65% and react for a third preset time to obtain an InGaN waveguide layer;

[0048] Among them, the V / III ratio of ammonia gas to the metal source is any value in the range of 500 - 1500:1, that is, the V / III ratio can be 500:1, 600:1, 700:1, 800:1, 900:1, 1000:1, 1100:1, 1200:1, 1300:1, 1400:1 or 1500:1, or any other value in the range of 500 - 1500:1. The growth rate ratio of the InGaN waveguide layer at the first preset time to that at the second preset time is any value in the range of 1.5 - 2.5, that is, the growth rate ratio of the InGaN waveguide layer at the first preset time and the second preset time can be 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4 or 2.5, or any other value in the range of 1.5 - 2.5. The reaction temperature at the first preset time is lower than that at the second preset time, and the temperature difference is any value in the range of 20°C - 50°C, that is, the reaction temperature at the first preset time can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C or 50°C lower than that at the second preset time, or any other value in the range of 20°C - 50°C lower than that at the second preset time. The metal source is a gallium source and an indium source. The flow rate of the indium source at the second preset time is any value in the range of 70 sccm - 150 sccm, that is, the flow rate of the indium source at the second preset time can be 70 sccm, 80 sccm, 90 sccm, 100 sccm, 110 sccm, 120 sccm, 130 sccm, 140 sccm or 150 sccm, or any other value in the range of 70 sccm - 150 sccm. The flow rate ratio of the indium source at the first preset time to that at the second preset time is any value in the range of 1.5 - 2.0, that is, the flow rate ratio of the indium source at the first preset time and the second preset time can be 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0, or any other value in the range of 1.5 - 2.0. The growth rate, reaction temperature and indium source flow rate within the third preset time are the same as those within the first preset time. The flow rate of ammonia gas is any value in the range of 15 slm - 40 slm. The flow rate of ammonia gas can be 15 slm, 20 slm, 25 slm, 30 slm, 35 slm or 40 slm, or any other value in the range of 15 slm - 40 slm.

[0049] In this embodiment, the preparation of the InGaN waveguide layer is divided into a first stage of reacting for a first preset time, a second stage of reacting for a second preset time, and a third stage of reacting for a third preset time. That is, by continuously introducing hydrogen, nitrogen, ammonia, and a metal source into the reaction chamber, and controlling the first partial pressure in the first stage to be any value between 50% and 65%, reducing the hydrogen partial pressure to any value between 40% and 50% in the second stage, and increasing the hydrogen partial pressure to any value between 50% and 65% in the third stage, and regulating the growth rate, reaction temperature, and indium source flow rate of the InGaN waveguide layer in the first stage and the third stage to be the same, and the growth rate and indium source flow rate in the first stage are significantly higher than those in the second stage, and the reaction temperature in the first stage is lower than that in the second stage, so as to prepare an InGaN waveguide layer with a thickness of any value between 200 nm and 320 nm and an indium content of any value between 6% and 11%. That is, the first partial pressure can be 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, or 65%, or any other value between 50% and 65%, the second partial pressure can be 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%, or any other value between 40% and 50%, and the third partial pressure can be 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, or 65%, or any other value between 50% and 65%.

[0050] In this embodiment, by adopting a relatively high first partial pressure, growth rate and a relatively low reaction temperature within the first preset time, the surface reaction rate and migration of In atoms are effectively inhibited, the roughness of the initial interface is reduced, and the epitaxial start is stabilized. Subsequently, within the second preset time, the reaction temperature is increased and the second partial pressure is reduced to 40%-50%. At the same time, combined with the regulation of the V / III ratio, the incorporation rate of In is increased and the crystal growth is promoted in an orderly manner, ensuring the formation of a high-quality thick InGaN layer. In addition, the precise regulation of the indium source flow rate and the growth rate in the first stage are set to be greater than that in the second stage, which helps to increase the effective In incorporation amount without causing phase separation. Finally, the reaction conditions in the third stage return to those in the first stage, further improving the surface morphology, reducing hole defects and stabilizing the terminal interface structure. That is, in this embodiment, by regulating the hydrogen partial pressure, reaction temperature, metal source flow rate and growth rate in segments, and by synergistically regulating the V / III ratio and ammonia flow rate, the synergistic optimization of multiple key process parameters is achieved, jointly ensuring high-quality epitaxial growth under the conditions that the thickness of the InGaN waveguide layer reaches 200 nm - 320 nm and the In content reaches 6% - 11%. At the same time, the crystal quality and composition uniformity of the InGaN waveguide layer are ensured, providing an excellent optical waveguide performance and device reliability basis for blue lasers.

[0051] In this embodiment, due to the difference in the thermal properties of hydrogen and nitrogen, there will be different reactant gas flow patterns. The migration of hydrogen through the gas source enhances the step-flow growth of the material and the surface diffusion length of gallium on the material. Increasing the hydrogen partial pressure will reduce the thickness of the gas thermal boundary layer above the substrate 10. Reducing the boundary layer can lead to fewer parasitic gas-phase reactions, resulting in a decrease in C, H, and O impurities in the grown film and an increase in the reliability of the device. At the same time, a relatively high V / III ratio results in poor surface atom migration, which will cause poor crystal quality and an increase in surface defects.

[0052] In this embodiment, during the preparation process of the InGaN waveguide layer, the hydrogen partial pressure is set to any value within 50% - 65% in the first and third stages of the growth of the entire InGaN waveguide layer, and the hydrogen partial pressure in the second stage is set to any value within 40% - 50%. This is because at the interface of the InGaN material, when the hydrogen partial pressure slightly increases, the interface defects are reduced, which is beneficial to thermal diffusion. At the same time, the degradation of the mobility is reduced. When the carriers are scattered by phonons and surface roughness, the mobility degradation at the interface is reduced, improving the reliability of the device.

[0053] In this embodiment, the flow rate of ammonia gas is any value between 15 slm and 40 slm, which can effectively reduce the saturation of the nitrogen source in the reaction chamber, so that the V / III ratio is any value between 500 and 1500:1, thereby preventing the enhancement of the gas-phase desorption and surface replacement reaction of In caused by too high ammonia flow rate, avoiding reducing its effective incorporation rate in the lattice, and at the same time being able to stabilize the surface migration behavior, contributing to obtaining a lower hole density and a smooth surface. When the thickness of the InGaN waveguide layer reaches more than 200 nm, it can reduce the interface instability caused by nitrogen source excess, which is beneficial to the continuity of crystal growth, thereby suppressing In composition modulation and phase separation.

[0054] In this embodiment, in the preparation method of the InGaN waveguide layer, first, a GaN layer is grown on a sapphire substrate. The growth temperature is any value between 1050 °C and 1080 °C, the pressure is 200 torr, the rotation speed is 1150 rpm / min, and the thickness of the GaN layer is any value between 2 μm and 4 μm. Then, an InGaN waveguide layer is grown on the GaN substrate, which can effectively reduce the dislocation density and improve the crystal quality, providing a high-quality epitaxial template for the subsequent InGaN waveguide layer, thereby improving the interface flatness and composition uniformity of the InGaN layer, suppressing the generation of defects and phase separation, and contributing to the stable and controllable growth of a thick InGaN waveguide layer with a high In composition.

[0055] In this embodiment, the thickness of the InGaN waveguide layer in the first stage and the third stage is any value between 0.5 nm and 1.5 nm, that is, the thickness of the InGaN waveguide layer grown within the first preset time and the second preset time can be 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1.0 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm or 1.5 nm, or any other value between 0.5 nm and 1.5 nm. By setting the thickness of the InGaN waveguide layer in the first stage and the third stage within the above range, the growth thickness of each layer can be precisely controlled, ensuring the uniformity and stability of the waveguide layer, as well as effectively improving the interlayer consistency of the InGaN waveguide layer, and enhancing the performance stability and reliability of the laser.

[0056] In a further embodiment, the first preset time is any value in the range of 25 s to 35 s, and the third preset time is the same as the first preset time. That is, the first preset time can be 25 s, 26 s, 27 s, 28 s, 29 s, 30 s, or 35 s, or any other value in the range of 25 s to 35 s. The third preset time can be 25 s, 26 s, 27 s, 28 s, 29 s, 30 s, or 35 s, or any other value in the range of 25 s to 35 s. In this embodiment, by precisely controlling the growth time of each stage and keeping the time of the high hydrogen partial pressure stage consistent, that is, the reaction times of the first stage and the third stage are the same, it helps to achieve the consistency and flatness of the growth interface of the InGaN waveguide layer, reduce the generation of surface roughness and hole defects. At the same time, the second stage provides sufficient crystal growth time within the same time scale, which is beneficial to the uniform epitaxy of the lattice and the stable incorporation of the In component, ensuring the compositional uniformity and crystallization integrity of the InGaN thick film.

[0057] In a further embodiment, the gallium source flow rate ratio of the first preset time to the second preset time is any value in the range of 1.5 to 2.5, and the third preset time has the same gallium source flow rate as the first preset time. That is, the gallium source flow rate ratio of the first preset time to the second preset time can be 1.5, 1.7, 2.0, 2.3, or 2.5, or any other value in the range of 1.5 to 2.5. In this embodiment, by increasing the gallium source flow rate in the first stage and the third stage to be significantly higher than that in the second stage, the instantaneous growth rate of the InGaN waveguide layer in the first stage and the third stage is increased, enabling the interface to be rapidly formed and the surface to be quickly covered, thereby improving the interface clarity and flatness, suppressing interface roughening and uneven nucleation. At the same time, appropriately reducing the Ga source supply in the second stage is beneficial to the effective doping and retention of In atoms, avoiding the competitive inhibition of In incorporation by Ga, and thus stably controlling the introduction of the In component and the lattice matching.

[0058] In a further embodiment, the flow rate of the gallium source at the second preset time is any value in the range of 50 sccm to 100 sccm, that is, the flow rate of the gallium source at the second preset time can be 50 sccm, 55 sccm, 60 sccm, 65 sccm, 70 sccm, 75 sccm, 80 sccm, 85 sccm, 90 sccm, 95 sccm or 100 sccm, or any other value in the range of 50 sccm to 100 sccm. In this embodiment, by setting the gallium flow rate at the second preset time within the above range, the growth rate of the InGaN waveguide layer in the second stage can be effectively regulated, and the competition relationship between Ga and In in the crystal lattice can be effectively controlled. While ensuring the stability of crystal growth, it can avoid excessive Ga source from inhibiting the effective incorporation of In, which helps to improve the actual doping efficiency and component uniformity of the In component, achieve precise control of the target In content. At the same time, it helps to reduce the accumulation of interface stress and mismatch defects, and improve the overall crystallization quality and optical uniformity of the InGaN waveguide layer.

[0059] In a further embodiment, the growth rate of the InGaN waveguide layer within the second preset time is any value in the range of 0.04 μm / h to 0.15 μm / h, that is, the growth rate of the InGaN waveguide layer within the second preset time can be 0.04 μm / h, 0.06 μm / h, 0.08 μm / h, 0.1 μm / h, 0.12 μm / h or 0.15 μm / h, or any other value in the range of 0.04 μm / h to 0.15 μm / h. In this embodiment, the growth rate within the above range helps to inhibit the phase separation and surface roughening phenomena in the high-In-component InGaN waveguide layer, extend the atomic migration and rearrangement time, promote the more stable incorporation of In atoms into the lattice sites, and significantly improve the component uniformity and crystal quality. At the same time, the above rate range matches the thermodynamic window of the high-In-component material, which can reduce the risk of thermal decomposition, enhance the In retention rate, and thus meet the growth requirements of high-quality thick InGaN waveguide layers. In addition, this growth rate is also beneficial to controlling the stress accumulation in the epitaxial layer, reducing the dislocation density, and improving the stability and reliability of the optoelectronic performance of the device.

[0060] In a further embodiment, the V / III ratio of ammonia to the metal source is any value in the range of 1000 - 1300:1, that is, the V / III ratio of ammonia to the metal source can be 1000:1, 1150:1, 1200:1, 1250:1 or 1300:1, or any other value in the range of 1000 - 1300:1. In this embodiment, the V / III ratio within the above range effectively balances the crystal growth rate and surface migration kinetics while ensuring sufficient nitrogen source supply to meet the complete reaction of the metal source, avoiding the hydrogen inhibition effect and reaction chamber supersaturation caused by too high ammonia flow rate. This helps to improve the crystal quality, reduce the surface roughness and reduce hole defects. In addition, it is also beneficial to control the incorporation efficiency of In, improve the compositional uniformity and structural integrity of the InGaN waveguide layer, so as to achieve the controllable growth of a high-quality, high-composition thick InGaN waveguide layer.

[0061] In a further embodiment, the reaction temperature in the second preset time is any value in the range of 700°C - 900°C, that is, the reaction temperature in the second preset stage can be 700°C, 750°C, 800°C, 850°C or 900°C, or any other value in the range of 700°C - 900°C. In this embodiment, growing the InGaN waveguide layer in the second stage within the above temperature range can achieve a good balance between improving the In incorporation rate and ensuring the crystal quality, so as to obtain an InGaN waveguide layer with both high compositional uniformity and excellent surface morphology.

[0062] In a further embodiment, the flow rate of nitrogen is any value in the range of 15 slm - 25 slm, and the flow rate of hydrogen is any value in the range of 10 slm - 40 slm. That is, the flow rate of nitrogen can be 15 slm, 16 slm, 17 slm, 18 slm, 19 slm, 20 slm, 21 slm, 22 slm, 23 slm, 24 slm or 25 slm, or any other value in the range of 15 slm - 25 slm. The flow rate of hydrogen can be 10 slm, 15 slm, 20 slm, 25 slm, 30 slm, 35 slm or 40 slm, or any other value in the range of 10 slm - 40 slm. In this embodiment, nitrogen within the above range is used as the main carrier gas to adjust the dilution degree and gas-phase transport rate of the reaction atmosphere, which helps to stabilize the reaction environment and improve the compositional uniformity of the thin film. Hydrogen, as an auxiliary gas, plays a dual role in the InGaN epitaxial process, that is, a medium proportion can promote the surface flattening and stress release of the crystal, while an excessive proportion may inhibit the incorporation of In. Therefore, by flexibly combining the hydrogen-nitrogen ratio within the above range, the hydrogen partial pressure and gas-phase kinetic process can be precisely regulated, optimizing the surface morphology of the thin film and reducing the defect density while meeting the high In composition requirement, thus improving the structural integrity and device stability of the InGaN waveguide layer.

[0063] In a further embodiment, the gallium source is triethylgallium and the indium source is trimethylindium. In this embodiment, using triethylgallium and trimethylindium as metal sources helps to precisely control the gallium and indium components in the InGaN waveguide layer during the epitaxial growth process, thereby achieving the desired thickness and In component of the InGaN layer. The above two source gases have high volatility and reactivity, can provide a high-purity and stable metal source supply at a relatively low temperature, ensure high-quality growth of the epitaxial layer, and can optimize the growth rate, improve the crystal quality of the thin film, reduce surface defects such as recessed holes, and improve the interlayer interface, thereby enhancing the optoelectronic performance and reliability of the device.

[0064] Figure 2 is a schematic structural diagram of a semiconductor laser according to an embodiment of the present invention.

[0065] As Figure 2 shown, the present invention also provides a semiconductor laser 100, including an InGaN waveguide layer obtained by the preparation method of any one of the above. In this embodiment, the semiconductor laser 100 includes a substrate 10, a lower confinement layer 20, a lower waveguide layer 30, a multi-quantum well light-emitting layer 40, an upper waveguide layer 50, an electron blocking layer 60, an upper confinement layer 70, and a contact layer 80, which are stacked in sequence from bottom to top. Among them, the material of the substrate 10 can be any one of sapphire, silicon carbide, gallium nitride, or a composite substrate. The composite substrate can be a composite material of aluminum oxide and gallium nitride or silicon carbide and gallium nitride. Here, the lower waveguide layer 30 and the upper waveguide layer 50 are the above-mentioned InGaN waveguide layers. Here, the preparation method of the InGaN waveguide layer will not be elaborated one by one.

[0066] In this embodiment, the semiconductor laser 100 is obtained by the following preparation method: First, an n-type GaN substrate is selected as the substrate 10, and the doping Si concentration is any value in 1×10 18 cm -3 -2×10 18 cm -3 The thickness of the n-type GaN substrate is 1000 nm; the lower confinement layer nAlGaN is grown on the n-type GaN substrate, the temperature is any value in 1000 °C - 1200 °C, the doping Al content is any value in 2% - 10%, and the doping Si concentration is in 1×10 18 cm -3 -5×10 18 cm -3 The thickness of the lower confinement layer nAlGaN is any value in 800 nm - 1500 nm; then an n-InGaN waveguide layer is grown on the lower confinement layer 20, the growth temperature is any value in 700 °C - 900 °C, the doping In content is any value in 6% - 11%, and the doping Si concentration is 1×10 18 cm -3-5×10 18 cm -3 Any value among the following: the thickness of the nInGaN waveguide layer is any value between 200 nm and 320 nm; the growth of the InGaN waveguide layer is carried out with the hydrogen partial pressure ratio being any value between 40% and 50%, and the V / III ratio of ammonia to metal source being any value between 500 - 1500:1. Moreover, during the 30 s before and after the growth of the InGaN waveguide layer, the hydrogen partial pressure is any value between 50% and 65%, and the thickness of the InGaN waveguide layer grown during the 30 s before and after is any value between 0.5 nm and 1.5 nm. Then, continue to grow the multi-quantum well light-emitting layer 40 on the nInGaN waveguide layer at a temperature of 700 °C - 900 °C, with the In doping content being any value between 6% and 11%, and the growth period being any value between 1 and 5. Among them, the thickness of the well is any value between 1 nm and 5 nm, and the thickness of the barrier is any value between 3 nm and 15 nm. Then, grow the upper waveguide layer uInGaN on the multi-quantum well light-emitting layer 40 at a growth temperature of any value between 700 °C and 900 °C, with the In doping content being any value between 6% and 11%, and the thickness being any value between 100 nm and 400 nm. The growth conditions of the upper waveguide layer 50 are the same as those of the lower waveguide layer 30. Then, continue to grow the electron blocking layer pAlGaN on the upper waveguide layer 50 at a growth temperature of any value between 800 °C and 1050 °C, with the Al doping content being any value between 15% and 25%, and the thickness of the electron blocking layer pAlGaN being any value between 5 nm and 30 nm, and the Mg doping concentration being in the range of 5×10 18 cm -3 -20×10 18 cm -3 Any value among the following: grow the upper confinement layer 70 on the electron blocking layer 60 at a temperature of any value between 900 °C and 1050 °C, with the Al doping content being any value between 5% and 10%, and the thickness being any value between 200 nm and 800 nm, and the Mg doping concentration being in the range of 1×10 18 cm -3 -20×10 18 cm -3 Any value among the following: then, continue to grow the pGaN contact layer on the upper confinement layer 70 at a growth temperature of any value between 850 °C and 1000 °C, with the thickness being any value between 10 nm and 50 nm, and the Mg doping concentration being greater than 1×10 20 cm -3 , and after the epitaxial growth of the device is completed, through processes such as chip manufacturing, a 450 nm blue laser 100 is fabricated.

[0067] Figure 9 is the AFM image of the semiconductor laser epitaxial wafer according to an embodiment of the present invention.

[0068] Such as Figure 9As shown in the AFM image of the semiconductor laser 100 prepared by the preparation method of the InGaN waveguide layer, the surface of the epitaxial wafer of the semiconductor laser 100 is flat and the defect density is low, indicating that applying the InGaN waveguide layer preparation process to grow the waveguide layer of the semiconductor laser 100 and the entire laser 100 epitaxial structure can obtain a laser 100 with almost no defects, improving the performance and reliability of the device.

[0069] The present application will be further described in detail below in conjunction with specific embodiments.

[0070] In some embodiments, hydrogen, nitrogen, ammonia, and a metal source are introduced into the reaction chamber. The metal source includes an indium source and a gallium source, and the preparation process of the InGaN waveguide layer is divided into a first stage, a second stage, and a third stage. First, the hydrogen partial pressure in the first stage is any value from 50% to 60%, the reaction time is any value from 25 s to 35 s, the growth rate in the first stage is any value from 0.08 μm / h to 0.3 μm / h, the reaction temperature is any value from 650 °C to 880 °C, and the indium source flow rate is any value from 105 sccm to 300 sccm. The hydrogen partial pressure in the second stage is any value from 40% to 50%, the growth rate is any value from 0.04 μm / h to 0.15 μm / h, the reaction temperature is any value from 700 °C to 900 °C, and the indium source flow rate is any value from 70 sccm to 150 sccm. The hydrogen partial pressure, growth rate, indium source flow rate, and reaction temperature in the third stage are the same as the corresponding parameter conditions in the first stage, and the V / III ratio of ammonia to the metal source in the first stage, second stage, and third stage is any value from 500 to 1500:1, and the ammonia flow rate is any value from 15 slm to 40 slm, to prepare an InGaN waveguide layer with a thickness of any value from 200 nm to 320 nm and an In content of any value from 6% to 11%.

[0071] Example 1

[0072] First, in the first stage of the InGaN waveguide layer preparation, the hydrogen partial pressure is 60%, the reaction time is 30 s, the growth rate in the first stage is 0.1 μm / h, the reaction temperature is 700 °C, and the indium source flow rate is 110 sccm. The hydrogen partial pressure in the second stage is 42%, the growth rate is 0.05 μm / h, the reaction temperature is 750 °C, and the indium source flow rate is 70 sccm. The hydrogen partial pressure, growth rate, indium source flow rate, and reaction temperature in the third stage are the same as the corresponding parameter conditions in the first stage, and the V / III ratio of ammonia to the metal source in the first stage, second stage, and third stage is 1062:1, and the ammonia flow rate is 32 slm, to prepare an InGaN waveguide layer with a thickness of 255 nm and an In content of 6.5%.

[0073] Comparative Example 1

[0074] The difference between Comparative Example 1 and Example 1 is only that the hydrogen partial pressure in the first stage and the third stage is the same as that in the second stage, that is, the hydrogen partial pressures in the first stage, the second stage, and the third stage are all 42%.

[0075] Comparative Example 2

[0076] The difference between Comparative Example 2 and Example 1 is only that the hydrogen partial pressure in the second stage is 0 and the V / III ratio of ammonia to the metal source is 2007:1.

[0077] Comparative Example 3

[0078] The difference between Comparative Example 3 and Example 1 is only that the hydrogen partial pressure in the second stage is 25% and the V / III ratio of ammonia to the metal source is 2007:1.

[0079] Comparative Example 4

[0080] The difference between Comparative Example 4 and Example 1 is only that the hydrogen partial pressure in the second stage is 25%.

[0081] Comparative Example 5

[0082] The difference between Comparative Example 5 and Example 1 is only that the hydrogen partial pressure in the second stage is 45% and the V / III ratio of ammonia to the metal source is 2007:1.

[0083] The corresponding InGaN waveguide layers were respectively prepared according to the reaction conditions in Example 1 and Comparative Examples 1 - 5, and the prepared InGaN waveguide layers were characterized by atomic force microscopy to obtain the AFM images as Figures 3 to 8 shown.

[0084] Figure 3 is the AFM image of the InGaN waveguide layer prepared according to Example 1 of the present invention, Figure 4 is the AFM image of the InGaN waveguide layer prepared according to Comparative Example 1 of the present invention, Figure 5 is the AFM image of the InGaN waveguide layer prepared according to Comparative Example 2 of the present invention, Figure 6 is the AFM image of the InGaN waveguide layer prepared according to Comparative Example 3 of the present invention, Figure 7 is the AFM image of the InGaN waveguide layer prepared according to Comparative Example 4 of the present invention, Figure 8 is the AFM image of the InGaN waveguide layer prepared according to Comparative Example 5 of the present invention.

[0085] As Figure 3As shown, the surface of the InGaN waveguide layer obtained in Example 1 is flat, with low roughness, low defect density, and almost no hole defects, indicating that the InGaN waveguide layer obtained by the reaction conditions in Example 1 can not only ensure the thickness and In-rich content of the InGaN waveguide layer, but also ensure the growth quality of the InGaN waveguide layer, preventing phase separation and local In-richness from resulting in a large defect density.

[0086] As Figures 4 to 8 shown, there are many hole defects on the surfaces of the InGaN waveguide layers obtained in Comparative Examples 1-5. The hole depth is relatively deep and the defect density is large, indicating that only by adjusting the hydrogen partial pressure or the V / III ratio of ammonia to metal source in a certain stage in Comparative Examples 1-5 cannot effectively improve the growth quality of the InGaN waveguide layer.

[0087] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0088] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for preparing an InGaN waveguide layer, characterized in that, The InGaN waveguide layer is used for the preparation of a blue laser. The thickness of the InGaN waveguide layer is any value from 200 nm to 320 nm, and the In content is any value from 6% to 11%. The preparation method includes: Introducing hydrogen, nitrogen, ammonia, and a metal source into the reaction chamber and reacting for a first preset time. The first partial pressure of the hydrogen is any value from 50% to 65%. Controlling the second partial pressure of the hydrogen to be any value from 40% to 50% and continuing the reaction for a second preset time. Controlling the third partial pressure of the hydrogen to be any value from 50% to 65% and reacting for a third preset time to obtain the InGaN waveguide layer. Wherein, the V / III ratio of the ammonia to the metal source is any value from 500 to 1500:

1. The growth rate ratio of the InGaN waveguide layer in the first preset time to that in the second preset time is any value from 1.5 to 2.

5. The reaction temperature in the first preset time is lower than that in the second preset time, and the temperature difference is any value from 20 °C to 50 °C. The metal source is a gallium source and an indium source. The flow rate of the indium source in the second preset time is any value from 70 sccm to 150 sccm. The flow rate ratio of the indium source in the first preset time to that in the second preset time is any value from 1.5 to 2.

0. The growth rate, reaction temperature, and the flow rate of the indium source in the third preset time are the same as those in the first preset time. The flow rate of the ammonia is any value from 15 slm to 40 slm. The growth rate of the InGaN waveguide layer in the second preset time is any value from 0.04 μm / h to 0.15 μm / h. The reaction temperature in the second preset time is any value from 700 °C to 900 °C.

2. The preparation method according to claim 1, wherein The first preset time is any value from 25 s to 35 s, and the third preset time is the same as the first preset time.

3. The preparation method according to claim 2, wherein The flow rate ratio of the gallium source in the first preset time to that in the second preset time is any value from 1.5 to 2.5, and the flow rate of the gallium source in the third preset time is the same as that in the first preset time.

4. The preparation method according to claim 3, wherein The flow rate of the gallium source in the second preset time is any value from 50 sccm to 100 sccm.

5. The preparation method according to claim 4, wherein The V / III ratio of the ammonia to the metal source is any value from 1000 to 1300:

1.

6. The preparation method according to claim 5, wherein The flow rate of the nitrogen is any value from 15 slm to 25 slm, and the flow rate of the hydrogen is any value from 10 slm to 40 slm.

7. The preparation method according to claim 6, wherein The gallium source is triethylgallium, and the indium source is trimethylindium.

8. A semiconductor laser, characterized in that, An InGaN waveguide layer obtained by the preparation method according to any one of claims 1-7.

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