Aluminum-based quantum well laser and in-situ interface processing method thereof

Abstract

The application relates to the technical field of semiconductor electronic devices, and discloses an aluminum-based quantum well laser and an in-situ interface processing method thereof. After a low-aluminum active region with a strain compensation structure is grown, and before a high-aluminum electron blocking layer is grown, the in-situ interface processing method comprises the following steps: maintaining the substrate temperature at a first temperature for a first time under a V-group source atmosphere; reducing the substrate temperature from the first temperature to a third temperature and inputting an aluminum source to perform strain surface pre-adsorption; then inputting the aluminum source and other III-group sources other than the aluminum source to grow a high-aluminum nucleation layer; and raising the substrate temperature from the third temperature to a fourth temperature to grow a main body part. The in-situ interface processing method of the application obtains a low-defect interface through the steps of strain surface relaxation, aluminum atom pre-adsorption, low-temperature nucleation and solid-state epitaxial transformation, so that the high-aluminum electron blocking layer and the low-aluminum active region below with the strain compensation structure are connected in a lattice, and the interface defect density is effectively reduced.

Description

Technical Field

[0001] This invention relates to the technical field of semiconductor electronic devices, and in particular to an aluminum-based quantum well laser and its in-situ interface processing method. Background Technology

[0002] Aluminum-based quantum well lasers (such as AlGaInP red lasers) generally include a low-aluminum active region with a strain-compensated structure and a high-aluminum electron blocking layer, which can ensure carrier confinement capability while avoiding aluminum oxidation in the low-aluminum active region.

[0003] Traditional in-situ interface treatment processes typically employ a two-step method: low-temperature nucleation and high-temperature annealing. Specifically, after growing the low-aluminum active region, the temperature is directly lowered to grow a thin high-aluminum nucleation layer to cover the strained surface. Subsequently, the temperature is raised for high-temperature annealing and the main body of the high-aluminum electron blocking layer continues to grow.

[0004] However, the strain surface of the low-aluminum active region with strain compensation structure is not an ideally flat atomic plane. If a high-aluminum material is grown directly on the strain surface of the low-aluminum active region with strain compensation structure to form a high-aluminum electron blocking layer, it is easy to form a discontinuous, multi-defect layer structure, which reduces the performance of the target device. Summary of the Invention

[0005] Therefore, the purpose of this invention is to overcome the technical problems in the prior art, such as uneven nucleation, increased interface defects, and strain transfer mismatch caused by the distortion of the atomic arrangement on the strain surface when growing a high-aluminum electron blocking layer on the strain surface of a low-aluminum active region with a strain compensation structure using a low-temperature nucleation method. This invention provides an aluminum-based quantum well laser and its in-situ interface treatment method, which obtains a low-defect strain interface through strain surface relaxation, aluminum atom pre-adsorption, low-temperature nucleation, and solid-state epitaxial transformation steps, so that the high-aluminum electron blocking layer and the underlying low-aluminum active region with a strain compensation structure can achieve lattice connection, effectively reducing the interface defect density.

[0006] To address the aforementioned technical problems, this invention provides an aluminum-based quantum well laser and its in-situ interface treatment method. In a metal-organic chemical vapor deposition (MOCVD) apparatus, after growing a low-aluminum active region with a strain-compensated structure and before growing a high-aluminum electron-blocking layer, the method includes the following steps:

[0007] Step A: Under a V-group source atmosphere, the substrate temperature is maintained at a first temperature for a first time; wherein the first temperature is higher than the growth temperature of the low-aluminum active region and lower than the nucleation temperature of the high-aluminum material, and the first time is 10 seconds to 60 seconds.

[0008] Step B: Under a V-group source atmosphere, the substrate temperature is lowered from the first temperature to the third temperature, and an aluminum source is introduced to perform strain surface pre-adsorption.

[0009] Step C: At the third temperature and in a Group V source atmosphere, an aluminum source and other Group III sources besides the aluminum source are introduced to grow a high-alumina nucleation layer;

[0010] Step D: Raise the substrate temperature from the third temperature to the fourth temperature for annealing. After annealing, grow the main body of the high-aluminum electron blocking layer at the fourth temperature.

[0011] Preferably, step A includes:

[0012] Step a1: Under a V-group source atmosphere, maintain the substrate temperature at a first temperature for a first time; wherein, the first temperature includes T low +30℃≤T1≤T low +80℃, where T1 is the first temperature, T low This is the growth temperature for the low-aluminum active region;

[0013] Step a2: When the duration of step a1 is 1 / 2 times the first time, an organosilane precursor is introduced into the reaction chamber of the metal-organic chemical vapor deposition equipment; wherein the introduction time of the organosilane precursor is 2 seconds to 10 seconds.

[0014] Preferably, in step a1, the group V source is phosphine, and the flow rate of the group V source is 1.5 to 3 times that of the group V source flow rate when growing the AlGaInP layer;

[0015] The organosilane precursor is selected from one of tert-butylsilane, diethylsilane and trimethylsilane, and the flow rate of the organosilane precursor is 0.5% to 2% of the flow rate of the group V source in step a1.

[0016] Preferably, step B includes the following steps:

[0017] Step b1: When the duration of step a1 is the first time, the substrate is cooled from the first temperature to the second temperature under the atmosphere of group V source and organosilane precursor; wherein the temperature difference between the second temperature and the first temperature is less than or equal to 50°C.

[0018] Step b2: When the substrate temperature is the second temperature, stop the introduction of organosilane precursor, and under the V-source atmosphere, lower the substrate temperature from the second temperature to the third temperature, and introduce an aluminum source for strain surface pre-adsorption.

[0019] Preferably, in step B, the substrate cooling rate is 5°C / second to 15°C / second;

[0020] The third temperature is 500°C to 580°C;

[0021] In step b2, the flow rate of the aluminum source is 1 / 10 to 1 / 3 of the flow rate of the aluminum source when growing the AlGaInP layer; the pre-adsorption time of the strained surface is 2 to 10 seconds.

[0022] In step b2, the aluminum source is trimethylaluminum.

[0023] Preferably, in step C:

[0024] The group V source is phosphine, and the flow rate of the group V source in step C is 1.5 to 3 times that of the group V source flow rate during the growth of the AlGaInP layer.

[0025] The ratio of the flow of Group V sources to the flow of all Group III sources is 300:1 to 500:1;

[0026] The aluminum source is trimethylaluminum;

[0027] Other Group III sources besides aluminum include trimethylgallium and trimethylindium;

[0028] The target thickness of the high-aluminum nucleation layer is 2 to 5 nanometers.

[0029] Preferably, step D includes:

[0030] Step d1: After growing the high-aluminum nucleation layer, all group III sources are turned off, the substrate temperature is maintained at the third temperature, and silane is introduced simultaneously in a group V source atmosphere to form a silicon passivation layer.

[0031] Step d2: Under a carrier gas atmosphere, the substrate is heated from the third temperature to the fourth temperature, and during the heating process, steps d21 and d22 are repeated.

[0032] Step d21: Turn off the growth pulse gas and introduce a reducing pulse gas for 100 to 300 milliseconds; the reducing pulse gas is phosphine; the growth pulse gas includes trimethylaluminum and triethylaluminum, and the flow rate ratio of trimethylaluminum to triethylaluminum is 1:4;

[0033] Step d22: Turn off the reducing pulse gas, introduce the closed growth pulse gas, and continue for 50 milliseconds to 150 milliseconds;

[0034] Step d3: When the substrate is at the fourth temperature, the main body of the high-aluminum electron blocking layer is grown in a group III source and a group V source atmosphere.

[0035] Preferably, step d1 includes:

[0036] Step d11: After growing the high-aluminum nucleation layer, turn off all group III sources and maintain the substrate temperature at the third temperature in the group V source atmosphere for 5 to 10 seconds; wherein, the flow rate of the group V source in step d11 is 1.5 to 3 times that of the group V source flow rate when growing the AlGaInP layer.

[0037] Step d12: In a group V source atmosphere, silane is simultaneously introduced for a duration of 1 to 3 seconds; wherein, the flow rate of silane in step d12 is 0.01% to 0.1% of the flow rate of group V source in step d11.

[0038] Preferably, the aluminum content in the high-alumina material is >0.8%.

[0039] The main body and the high-aluminum nucleation layer together constitute the high-aluminum electron blocking layer, wherein the aluminum composition of the high-aluminum nucleation layer is higher than that of the main body.

[0040] The fourth temperature is 680°C to 720°C;

[0041] The flow rate of the growth pulse gas is 1 / 20 to 1 / 10 of the aluminum source flow rate during continuous growth of the high-alumina electron blocking layer;

[0042] In step d21, the ratio of the flow rate of the group V source to the flow rate of the group III source in the gas phase boundary layer of the strained surface is greater than 1000.

[0043] The carrier gas is hydrogen or deuterium;

[0044] In step d3, the group V source is phosphine, and the group V source flow rate is the group V source flow rate during the growth of the AlGaInP layer.

[0045] In step d3, the ratio of the flow rate of the V-source to the flow rate of the III-source is 100 to 200.

[0046] In step d3, the group III source includes an aluminum source, a gallium source, and an indium source; wherein the aluminum source is trimethylaluminum, the gallium source is trimethylgallium, and the indium source is trimethylindium;

[0047] In step D, the heating rate is from 10°C / second to 25°C / second.

[0048] On the other hand, the present invention discloses an aluminum-based quantum well laser prepared by an in-situ interface processing method, comprising a substrate, a lower confinement layer, a lower waveguide layer, a low-aluminum active region, a high-aluminum electron blocking layer, an upper waveguide layer, an upper confinement layer, and a contact layer arranged sequentially.

[0049] The low-aluminum active region includes a strain compensation structure, which comprises multiple alternating layers of compressive strain quantum wells and tensile strain barrier layers.

[0050] Compared with the prior art, the above-described technical solution of the present invention has the following advantages:

[0051] The in-situ interface treatment method for aluminum-based quantum well lasers described in this invention obtains a low-defect strain interface through strain surface relaxation, aluminum atom pre-adsorption, low-temperature nucleation, and solid-state epitaxial transformation steps. Specifically: the strain surface relaxation step reduces or even eliminates the lattice distortion of the strain surface, providing a near-ideal surface template for heteroepitaxial growth. The aluminum atom pre-adsorption step guides the nucleation and growth of a high-alumina electron blocking layer. Furthermore, by combining the strain surface relaxation step and the aluminum atom pre-adsorption step, lattice bonding is achieved between the high-alumina electron blocking layer and the underlying low-alumina active region with a strain compensation structure, effectively reducing the defect density at the strain interface. Attached Figure Description

[0052] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0053] Figure 1 This is a schematic diagram of an aluminum-based quantum well laser in an embodiment of the present invention.

[0054] Figure 2 This is a schematic diagram of a low-aluminum active region in an embodiment of the present invention.

[0055] Figure 3 This is a flowchart illustrating an in-situ interface processing method in an embodiment of the present invention.

[0056] Figure 4 This is a schematic diagram of a high-aluminum electron blocking layer in an embodiment of the present invention.

[0057] Figure 5 This is a schematic diagram of an in-situ interface processing system in an embodiment of the present invention.

[0058] Explanation of reference numerals in the accompanying drawings: 11. Substrate; 12. Lower confinement layer; 13. Lower waveguide layer; 14. Low-aluminum active region; 141. Tensile strain barrier layer; 142. Compressive strain quantum well layer; 15. High-aluminum electron blocking layer; 151. High-aluminum nucleation layer; 152. Main body; 16. Upper waveguide layer; 17. Upper confinement layer; 18. Contact layer; 21. Reaction chamber; 22. Pulse sequence generator; 23. Growth pulse pipeline; 231. Valve B; 24. Reduction pulse pipeline; 241. Valve A; 25. Growth pulse gas source; 26. Reduction pulse gas source. Detailed Implementation

[0059] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0060] In the strain-compensated structure of the low-aluminum active region 14 with multiple quantum wells, the lattice constants of the compressive strain quantum well layer 142 and the tensile strain barrier layer 141 are periodically mismatched in the vertical direction. After the growth of the low-aluminum active region 14 with multiple quantum wells and strain compensation structure, the top surface (i.e., the strain surface) is not an ideal atomic plane. Due to the periodic variation of the lattice constants of the underlying compressive strain quantum well layer 142 and tensile strain barrier layer 141, this variation is transmitted to the atomic layers of the strain surface, causing distortion of the atomic arrangement and bond length / bond angle on the strain surface, forming a metastable strain surface with higher energy.

[0061] If high-alumina materials are grown directly on a twisted, high-energy strained surface to form a high-alumina electron blocking layer15, aluminum atoms tend to nucleate at locations with uneven energy, easily leading to three-dimensional island-like growth and the formation of discontinuous, defect-laden layer structures. This not only disrupts the steepness of the interface but also introduces a large number of interface states, which become nonradiative recombination centers for charge carriers, degrading device performance, such as accelerating efficiency decay.

[0062] Some patent documents have addressed band structure setup, strain compensation, and general interface treatment, but they have not recognized the impact of the strained surface itself on the quality of subsequent heteroepitaxial nucleation, and still assume that the strained surface used for growth is ideally flat.

[0063] This invention discloses an aluminum-based quantum well laser and its in-situ interface processing method.

[0064] Example 1: This example discloses an in-situ interface processing method for aluminum-based quantum well lasers.

[0065] The in-situ interface processing method of this embodiment is applicable to aluminum-based quantum well lasers (e.g., AlGaInP-based lasers or AlGaAs-based lasers) that include a low-aluminum active region 14 with a strain-compensated structure and a high-aluminum electron blocking layer 15.

[0066] When applying, refer to Figure 1 The aluminum-based quantum well laser comprises, from bottom to top, a substrate 11, a lower confinement layer 12, a lower waveguide layer 13, a low-aluminum active region 14, a high-aluminum electron blocking layer 15, an upper waveguide layer 16, an upper confinement layer 17, and a contact layer 18. Further, refer to... Figure 2 The low-aluminum active region 14 includes an alternating compressive strain quantum well layer 142 and a tensile strain barrier layer 141, with an alternation cycle of 3-5 for the compressive strain quantum well layer 142 and the tensile strain barrier layer 141.

[0067] In practical applications, to break the original distorted state of the strained surface and relocate and rearrange it into a surface template that is more thermodynamically stable, has a more regular atomic arrangement, and a more uniform chemical potential, this embodiment performs steps A to D in a metal-organic chemical vapor deposition (MOCVD) apparatus after growing the low-aluminum active region 14 with a strain-compensated structure and before growing the high-aluminum electron blocking layer 15. This achieves in-situ interface processing of the aluminum-based quantum well laser. (Refer to...) Figure 3 .

[0068] Step A: Under a V-group source atmosphere, the substrate 11 temperature is maintained at a first temperature for a first time. Through strain surface relaxation and reconstruction, the atomic arrangement distortion caused by the strain compensation structure below the strain surface of the low-aluminum active region 14 is eliminated, and a more thermodynamically stable strain surface is provided for subsequent processing.

[0069] In applications, within the AlGaInP / GaAs system, Group V sources typically refer to phosphine (PH3) and arsine (AsH3), used to provide phosphorus and arsenic elements, respectively. Phosphine is used for the growth of various AlGaInP layers, such as confinement layers, waveguide layers, active regions, and electron blocking layers. Arsenine is used for deoxidation protection of the GaAs substrate 11, growth of the GaAs buffer layer, and growth of the GaAs contact layer 18. Furthermore, the strained surface treated in step A is adjacent to the low-aluminum active region 14 (e.g., the AlGaInP active region). To avoid introducing As contamination, the Group V source in step A of this embodiment is phosphine.

[0070] In addition, in order to ensure sufficient phosphorus pressure in the MOCVD reaction chamber 21, which strongly suppresses the desorption of indium and gallium atoms on the strained surface and allows for thermal etching of any trace amounts of unstable oxides (e.g., phosphorus oxides, metastable gallium oxides, and metastable indium oxides) that may be present at the first temperature, the flow rate of the group V source in step A of this embodiment is 1.5 to 3 times that of the group V source flow rate when growing the AlGaInP layer.

[0071] In practical applications, to avoid premature deposition and without triggering rapid nucleation of high-alumina materials, slightly higher energy is used to promote relaxation and reconstruction of the strain surface of the low-alumina active region 14. In this embodiment, the first temperature is higher than the growth temperature of the low-alumina active region 14 but lower than the nucleation temperature of the high-alumina material. The nucleation temperature of the high-alumina material is the initial growth temperature used in a continuous MOCVD growth process to begin growing the high-alumina material on a flat and stable substrate 11 or buffer layer. The growth temperature of the low-alumina active region 14 is the substrate 11 temperature set during the growth of the compressive strain quantum well layer 142 and the tensile strain barrier layer 141 of the low-alumina active region 14.

[0072] To ensure that the high-alumina electron blocking layer 15 has a sufficiently high conduction band barrier (e.g., a conduction band barrier greater than 300 meV) to effectively confine electrons, when the high-alumina material is high-alumina AlGaInP, the aluminum composition is >0.8; when the high-alumina material is high-alumina AlGaAs, the aluminum composition is >0.9. Preferably, in this embodiment, the high-alumina material is high-alumina AlGaInP, and the aluminum composition is >0.8.

[0073] In actual implementation, in order to meet the time required for the atomic relaxation of the strained surface and to avoid excessive etching, the first time in this embodiment is 10 to 60 seconds.

[0074] The low-aluminum active region 14 is composed of indium-containing materials (such as GaInP or low-aluminum AlGaInP). In AlGaInP crystals, indium, gallium, and aluminum are bonded to phosphorus. Among these, indium has a large atomic radius and low electronegativity, resulting in the lowest In-P bond energy with phosphorus, making it the most easily broken. When strain surface relaxation is performed at the first temperature, the thermal decomposition of group V sources (e.g., phosphine PH3) at higher temperatures intensifies, generating highly reactive phosphorus free radicals. These phosphorus free radicals may over-etch the strain surface, especially for strain surfaces with high indium content, leading to the desorption of indium atoms from the strain surface. The selective removal of indium atoms from the strain surface results in an unintentional decrease in the indium content of several atomic layers, thereby altering the stoichiometry of the strain surface and causing it to deviate from the target value. Since the atomic radius of indium is much larger than that of gallium and aluminum, the strain surface with missing indium atoms and stoichiometric imbalance can lead to increased lattice mismatch and more point defects (such as vacancies) when used as a surface template for epitaxy of high-aluminum materials in subsequent steps (such as steps B and C), which may result in strain surfaces that are not conducive to two-dimensional layered growth.

[0075] In traditional high-temperature processing or low-temperature nucleation, either the initial temperature is higher (generally greater than 750°C) but the initial time is shorter (generally 1 to 5 seconds), resulting in a high rate of phosphorus free radical generation and instantaneous high concentration of phosphorus free radicals; or the initial temperature is lower (generally around 550°C), leading to incomplete decomposition of phosphine and a lower concentration of phosphorus free radicals, thus resulting in insignificant desorption of indium atoms from the strain surface. In this embodiment, the initial temperature is medium and the initial time is relatively long, resulting in a moderate rate of phosphorus free radical generation and continuous generation of phosphorus free radicals. Therefore, the desorption of indium atoms from the strain surface is severe.

[0076] The goal of step A in this embodiment is to reorganize the atoms on the strained surface to obtain a smoother strained surface. However, phosphorus radicals preferentially react with and desorb indium atoms, which have weaker binding energy to the strained surface. Therefore, in some embodiments, in step A, an organosilane precursor competes with excess phosphorus radicals for surface active sites to protect indium atoms. The organosilane precursor can be one of tert-butylsilane ((CH3)3CSiH3), diethylsilane ((C2H5)2SiH2), and trimethylsilane ((CH3)3SiH). Preferably, the organosilane precursor is tert-butylsilane.

[0077] Specifically, step A includes at least step a1 and step a2.

[0078] Step a1: Under a V-group source atmosphere, maintain the temperature of substrate 11 at a first temperature for a first time.

[0079] When applied, the first temperature includes T low +30℃≤T1≤T low +80℃, where T1 is the first temperature, T low The growth temperature of the low-aluminum active region 14 is used. Strain surface relaxation and reconstruction are performed in a temperature range that is slightly higher than the growth temperature of the low-aluminum active region 14 (e.g., the growth temperature of the low-aluminum active region 14 is 650℃), but lower than the nucleation temperature of the high-aluminum material (e.g., the nucleation temperature of the high-aluminum material is 700℃). This allows the surface atoms to have sufficient kinetic energy for migration and recombination (relaxation), but does not induce uncontrolled nucleation of the high-aluminum material.

[0080] In practical applications, the initial time is 10 to 60 seconds, which is sufficient to allow the atoms on the strained surface to complete migration and for the strained surface to achieve stable reconstruction, while avoiding excessive etching and side reactions caused by excessive time.

[0081] In actual implementation, the Group V source in step a1 is phosphine, and the flow rate of the Group V source in step a1 is 1.5 to 3 times that of the Group V source during AlGaInP layer growth, forming a strong protective atmosphere and inhibiting the desorption of indium and gallium atoms from the strained surface. At the same time, the active phosphorus free radicals generated by the decomposition of phosphine at high temperature have a thermal etching cleaning effect on trace unstable impurities (such as phosphorus suboxides) on the strained surface.

[0082] Step a2: When the duration of step a1 is the first time, an organosilane precursor is introduced into the reaction chamber 21 of the metal-organic chemical vapor deposition equipment.

[0083] In application, in order to avoid excessively suppressing the necessary migration of atoms on the strained surface and hindering the relaxation process, at the beginning of step a1 at 1 / 2 of the first time, while keeping the atmosphere of the group V source (e.g., PH3) constant, an organosilane precursor is simultaneously introduced into the MOCVD reaction chamber 21, and the temperature of the substrate 11 is maintained at the first temperature.

[0084] Organosilanes (e.g., tert-butylsilane) decompose at the first temperature to produce silane groups (e.g., -SiH3, -SiH2-), which have high surface mobility. The silane groups rapidly adsorb onto indium atom sites on the strained surface, forming a temporary passivation layer. This temporary passivation layer is a monolayer and metastable.

[0085] The interaction between silane groups and group III atoms (indium and gallium atoms) on the strained surface is mainly a weak interaction such as coordination bonds and van der Waals forces, rather than covalent or ionic bonds. Therefore, the temporary passivation layer does not enter the crystal structure, but occupies sites through physicochemical adsorption, thereby preventing subsequent highly reactive phosphorus radicals from directly attacking and removing indium atoms. This reduces the overall migration rate of atoms on the strained surface, guiding the strained surface reconstruction process to proceed gently and uniformly, and thus avoiding the formation of local rough regions due to rapid desorption of indium atoms.

[0086] In practical applications, the introduction time of the organosilane precursor is the shortest time required for it to reach saturated monolayer adsorption on the strained surface. That is, after the organosilane precursor is introduced, silane adsorption alters the scattering signal on the strained surface. Once the scattering signal stabilizes, it indicates that saturated monolayer adsorption has been completed, forming a temporary passivation layer. At this point, the introduction of the organosilane precursor is stopped. The introduction time of the organosilane precursor is typically 2 to 10 seconds.

[0087] Furthermore, in order to ensure a certain adsorption rate (i.e., to form a temporary passivation layer within the time of introduction of the organosilane precursor to ensure complete coverage and protection) and to avoid the formation of multiple temporary passivation layers, the flow rate of the organosilane precursor in this embodiment is 0.5% to 2% of the flow rate of the group V source in step a1.

[0088] Step B: Under a V-source atmosphere, the temperature of substrate 11 is reduced from the first temperature to the third temperature, and an aluminum source is introduced for strain surface pre-adsorption, so as to pre-adsorb a layer of aluminum atoms on the surface template in an orderly manner, which facilitates the subsequent growth of high-aluminum nucleation layer 151.

[0089] In application, as the temperature decreases from the initial temperature, the adsorption binding energy between the silane and the strain surface decreases. Under the blowing and thermal desorption of the V-source atmosphere, the silane will desorb from the strain surface in an orderly and layer-by-layer manner, and the desorption process will preferentially start from the region with the lowest and most stable surface energy (i.e., the region that is the flattest after reconstruction and whose stoichiometry is closest to the target value), thereby obtaining a strain surface with a stoichiometry closer to the target value.

[0090] However, if the cooling rate is too slow (e.g., less than 5 °C / s), the silane desorption process is too long, increasing the exposure time of the protected strained surface at high temperatures, which may lead to erosion by background impurities. If the cooling rate is too fast (e.g., greater than 15 °C / s), the silane desorption may be uneven, potentially causing disturbances in the atomic arrangement of the strained surface. To ensure orderly and complete desorption of the organosilane precursor while minimizing the adverse effects of the thermal process on the relaxed surface and maintaining the integrity of the surface template, a first cooling rate of 5 °C / s to 15 °C / s is adopted.

[0091] In practical applications, step B may include steps b1 and b2.

[0092] Step b1: When the duration of step a1 is the first time, the substrate 11 is cooled from the first temperature to the second temperature under the atmosphere of group V source and organosilicon precursor.

[0093] In application, after step a1, the substrate 11 is cooled from the first temperature to the second temperature under the atmosphere of a group V source and an organosilane precursor.

[0094] In practical applications, in order to guide the silane to desorb smoothly and layer by layer, the most stable region is preferred to be started first, so as to obtain a strain surface with a stoichiometric ratio closer to the target value and provide a better surface template for subsequent pre-adsorption. In this embodiment, the temperature difference between the second temperature and the first temperature is less than or equal to 50°C, so as to reduce the adsorption binding energy between the silane and the strain surface, while avoiding disturbing the already relaxed surface structure.

[0095] Step b2: When the temperature of substrate 11 is the second temperature, stop the introduction of organosilane precursor, continue to lower the temperature of substrate 11 from the second temperature to the third temperature under the V group source atmosphere, and introduce aluminum source for strain surface pre-adsorption.

[0096] In application, the aluminum source is trimethylaluminum. The third temperature is the temperature of the aluminum atom pre-adsorption step, which must meet two conditions: (1) below the temperature at which silanes can exist stably, to ensure that silanes have been completely desorbed; (2) above the temperature at which the aluminum source can effectively undergo surface adsorption, but without triggering rapid three-dimensional growth. Specifically, the third temperature can be 500℃ to 580℃, so that aluminum atoms have sufficient surface mobility, but the growth rate is relatively slow. This allows for the monolayer ordered pre-spreading of aluminum atoms on the surface template, facilitating the subsequent growth of a high-alumina nucleation layer 151.

[0097] In practical applications, during the cooling process of substrate 11 from the second temperature to the third temperature, or when the substrate 11 reaches the third temperature, an aluminum source is introduced for strain surface pre-adsorption. Introducing the aluminum source for strain surface pre-adsorption during the cooling process or when the third temperature is reached (i.e., when the temperature drops to near the third temperature) ensures that the start of aluminum atom pre-adsorption coincides precisely with the moment when the silane groups are almost completely desorbed and the surface template is just exposed. At this point, the stoichiometry of the strain surface is closer to the target value, the atomic arrangement is more ordered, and aluminum atoms can immediately occupy lattice sites, achieving efficient and uniform adsorption and avoiding the possibility of recontamination or relaxation of the surface template due to prolonged exposure.

[0098] In actual implementation, in order to prevent epitaxial growth during aluminum atom pre-adsorption, the aluminum source flow rate during pre-adsorption is set to 1 / 10 to 1 / 3 of the aluminum source flow rate during AlGaInP layer growth, and the strain surface pre-adsorption time is 2 to 10 seconds. This allows aluminum atoms sufficient time to migrate and occupy lattice sites on the strain surface to cover it, while also preventing aluminum atom accumulation and epitaxial growth due to excessive aluminum source flux.

[0099] Step C: At the third temperature and in a group V source atmosphere, an aluminum source and other group III sources other than the aluminum source are introduced to grow a high-alumina nucleation layer 151.

[0100] In application, a high-alumina nucleation layer 151 (aluminum composition > 0.8%) is grown on a surface template pre-adsorbed with aluminum atoms, serving as a transition between the strain surface and the main body 152 of the high-alumina electron blocking layer 15. If the high-alumina nucleation layer 151 is too thin (e.g., less than 2 nm), the strain surface coverage will be discontinuous and incomplete; if the high-alumina nucleation layer 151 is too thick (e.g., greater than 5 nm), the crystal quality will decrease during low-temperature growth. Therefore, the target thickness of the high-alumina nucleation layer 151 is 2 to 5 nm.

[0101] In practical applications, in step C, the Group V source is phosphine, and the flow rate of the Group V source in step C is 1.5 to 3 times that of the Group V source during AlGaInP layer growth. Furthermore, the aluminum source is trimethylaluminum, and other Group III sources besides aluminum include trimethylgallium and trimethylindium. The flow rate ratio of the Group V source to all Group III sources is 300:1 to 500:1, which can prevent agglomeration on the strained surface due to insufficient low-temperature mobility.

[0102] In actual implementation, the group III source releases metal atoms through thermal decomposition in the MOCVD reaction chamber 21, which react with the group V source to form compound semiconductors (such as AlGaAs crystals and AlGaInP crystals), namely the high-aluminum nucleation layer 151.

[0103] Step D: Raise the temperature of substrate 11 from the third temperature to the fourth temperature for annealing. After annealing, grow the main body 152 of the high-aluminum electron blocking layer 15 at the fourth temperature.

[0104] When applying, refer to Figure 4 The main body 152 and the high-aluminum nucleation layer 151 together constitute the high-aluminum electron blocking layer 15, wherein the aluminum composition of the high-aluminum nucleation layer 151 is higher than that of the main body 152. The fourth temperature is the growth temperature of the main body 152. Specifically, the growth temperature of the main body 152 is the substrate 11 temperature during the growth of the high-aluminum electron blocking layer 15 in MOCVD, without considering special interface treatment, which is generally 680°C to 720°C.

[0105] During the heating process, the high-alumina nucleation layer 151 transforms from a metastable structure grown at low temperatures to a stable crystal structure grown at high temperatures through solid-state diffusion and atomic rearrangement, achieving solid-state epitaxial crystallization. Specifically, solid-state diffusion involves the short-range migration of aluminum, gallium, indium, and phosphorus atoms within the high-alumina nucleation layer 151 via lattice vacancy mechanisms, resulting in a more uniform composition distribution. Atomic rearrangement involves the thermally driven adjustment of the positions of aluminum, gallium, indium, and phosphorus atoms within the high-alumina nucleation layer 151 within the lattice, transforming from a metastable arrangement with potential point defects formed during low-temperature growth to a more stable and perfect crystal arrangement.

[0106] In high-alumina materials (such as high-alumina nucleation layer 151), the aluminum-arsenic (Al-As) bonds or aluminum-phosphorus (Al-P) bonds are relatively weaker at high temperatures. In the early stages of heating, such as from the third temperature to 650°C, if the strain surface group V (i.e., phosphorus atoms) protection is insufficient, aluminum atoms may detach from the lattice and volatilize in the form of low-valence alumina or metallic aluminum clusters, resulting in pores or amorphous regions in the high-alumina nucleation layer 151 and disrupting the continuity of the high-alumina nucleation layer 151.

[0107] To prevent thermal decomposition, an excess of Group V source (phosphine) is typically introduced for protection. However, within a specific temperature window during the heating process (e.g., 500°C to 650°C), the catalytic decomposition of the excess Group V source generates a large number of highly reactive hydrogen atoms (H·). These highly reactive hydrogen atoms have strong reducing properties and can abstract oxygen from H₂O or O₂ to generate hydroxyl radicals (·OH) and water (H₂O). Furthermore, during the heating process, surface aluminum atoms become loose due to intensified thermal vibrations (the binding energy temporarily decreases). The Al-O bond has a high bond energy (approximately 501 kJ / mol) and is very stable. Therefore, hydroxyl radicals (·OH) preferentially combine with the loose aluminum atoms, which are more likely to form stable bonds, to generate Al-O-Al or Al-OH structures that are difficult to remove, causing re-oxidation and resulting in defects in the high-alumina nucleation layer 151. However, in this embodiment, during the solid-state epitaxial crystallization process, the high-alumina nucleation layer 151 has sufficient time to experience the specific temperature window and undergo re-oxidation.

[0108] In some embodiments, the heating rate of substrate 11 in step D is from 10°C / second to 25°C / second. This avoids a heating rate of substrate 11 that is too slow (e.g., less than 10°C / second), causing the high-aluminum nucleation layer 151 to remain in a specific temperature window for too long, increasing the risk of re-oxidation and thermal decomposition; and avoids a heating rate of substrate 11 that is too fast (e.g., greater than 25°C / second), resulting in excessive thermal stress and insufficient time for atoms to complete solid-state epitaxial rearrangement through short-range diffusion.

[0109] In some further embodiments, during the heating process, step D employs periodically alternating reducing pulses and growth pulses to suppress thermal decomposition and re-oxidation in a time-sharing manner. Specifically, step D may include steps d1 to d3.

[0110] Step d1: After growing the high-aluminum nucleation layer 151, all group III sources are turned off, the temperature of the substrate 11 is maintained at the third temperature, and silane is introduced simultaneously in a group V source atmosphere to form a silicon passivation layer.

[0111] When applied, step d1 may include steps d11 and d12.

[0112] Step d11: After growing the high-alumina nucleation layer 151, turn off all group III sources and maintain the substrate 11 at the third temperature in a group V source atmosphere for 5 to 10 seconds to allow the surface of the high-alumina nucleation layer 151 to reach thermal and chemical equilibrium in a stable atmosphere.

[0113] In application, the flow rate of the V-group source in step d11 is 1.5 to 3 times that of the V-group source flow rate during AlGaInP layer growth to provide a strong protective atmosphere.

[0114] Step d12: After step d11, silane (SiH4) is simultaneously introduced into a V-source atmosphere for 1 to 3 seconds to complete the adsorption of sub-monolayer silicon atoms (to avoid the formation of multilayers).

[0115] In application, the silane flow rate in step d12 is 0.01% to 0.1% of the flow rate of the group V source in step d11, in order to avoid excessive silane flow rate leading to silicon doping or the formation of silicides.

[0116] In practical applications, silane decomposes at low temperatures (i.e., the third temperature), and the resulting silicon atoms rapidly adsorb onto the aluminum atoms on the outermost surface of the high-alumina nucleation layer 151, forming a sub-monolayer silicon passivation layer. Furthermore, silicon has a high binding energy with oxygen, allowing it to preemptively occupy the active sites of aluminum atoms in the initial stages of subsequent heating, forming SiO₂. x It acts as a barrier to preferentially resist the invasion of trace oxygen and reduce the formation of Al-O bonds.

[0117] Step d2: Under a carrier gas atmosphere (e.g., hydrogen or deuterium), the substrate 11 is heated from the third temperature to the fourth temperature, and during the heating process, steps d21 and d22 are repeated.

[0118] Step d21: Turn off the growth pulse gas and introduce a reducing pulse gas for 100 to 300 milliseconds. The reducing pulse gas is phosphine.

[0119] In application, all metal sources (e.g., group III sources) are shut off, and a group V source (e.g., phosphine) is introduced. In the gas boundary layer near the strained surface, the flow rate ratio of the group V source to the group III source is greater than 1000, resulting in a transiently high V / III ratio (>1000) locally on the surface. At high temperatures, phosphine decomposes to produce a large number of hydrogen / deuterium atoms, generating a hydrogen / deuterium-rich environment. The hydrogen / deuterium atoms actively etch and remove unstable Al clusters and fragile Al-O bonds generated during heating, carrying them away in the form of H2O / D2O, thus inhibiting re-oxidation. It is worth noting that Si-O bonds are also removed by hydrogen / deuterium atoms, thereby protecting the aluminum atoms in the high-aluminum nucleation layer 151.

[0120] Step d22: Turn off the reducing pulse gas, introduce the closed growth pulse gas, and continue for 50 milliseconds to 150 milliseconds.

[0121] During application, stop the flow of phosphine and introduce growth pulse gas (a mixed aluminum source of trimethylaluminum and triethylaluminum with a flow rate ratio of 1:4), and the flow rate of the growth pulse gas is 1 / 20 to 1 / 10 of the aluminum source flow rate when continuously growing the high-aluminum electron blocking layer 15.

[0122] In practical applications, triethylaluminum is more stable than trimethylaluminum at lower temperatures and decomposes more gradually. Taking advantage of the gradual decomposition of triethylaluminum, selective epitaxial repair of aluminum atoms can be performed on freshly cleaned active aluminum sites (aluminum bond breaks), promoting lattice ordering. Simultaneously, the rapid reactivity of trimethylaluminum ensures repair efficiency, jointly suppressing thermal decomposition.

[0123] By cycling through cleaning in step d21 and repair in step d22, not only is the quality deterioration of the high-alumina nucleation layer 151 avoided during the heating process, but the crystal quality of the high-alumina nucleation layer 151 is also improved by annealing through solid-state epitaxial crystallization, making it comparable to materials grown directly at high temperatures.

[0124] In some embodiments, reference Figure 5 The in-situ interface processing system is equipped with a pulse sequence generator 22, a reducing pulse pipeline 24, and a growth pulse pipeline 23. One end of the reducing pulse pipeline 24 is connected to the reaction chamber 21, and the other end is connected to a reducing pulse gas source 26. One end of the growth pulse pipeline 23 is connected to the reaction chamber 21, and the other end is connected to a growth pulse gas source 25. The pulse sequence generator 22 controls the opening and closing of valve A241 on the reducing pulse pipeline 24 and valve B231 on the growth pulse pipeline 23.

[0125] Step d3: When the substrate 11 is at the fourth temperature, the main body 152 of the high-aluminum electron blocking layer 15 is grown in a group III source and a group V source atmosphere.

[0126] In application, after the temperature of substrate 11 is raised to the growth temperature of the main body portion 152, that is, after the temperature of substrate 11 is raised to the fourth temperature, the temperature of substrate 11 is maintained at the fourth temperature for at least 30 seconds to perform annealing.

[0127] In practical applications, after the temperature of substrate 11 is raised to the growth temperature of the main body portion 152, the continuous growth mode is resumed. Specifically, the flow rate of the group V source (e.g., phosphine) is the same as the group V source flow rate during AlGaInP layer growth; the ratio of the flow rate of the group V source to the flow rate of the group III source (including aluminum, gallium, and indium sources; wherein the aluminum source is trimethylaluminum, the gallium source is trimethylgallium, and the indium source is trimethylindium) is 100 to 200.

[0128] In actual implementation, a p-type doping source (such as dicyclopentadienyl magnesium) is also required for p-type doping. The flow rate of the p-type doping source is such that the hole concentration of the main body portion 152 of the high-alumina electron blocking layer 15 reaches 5 × 10⁻⁶. 17 cm -3 Up to 1×10 18 cm -3 As the standard.

[0129] Example 2: This example discloses an aluminum-based quantum well laser.

[0130] The aluminum-based quantum well laser in this embodiment can be prepared using the in-situ interface treatment method described in Embodiment 1.

[0131] The aluminum-based quantum well laser of this embodiment includes a substrate 11, a lower confinement layer 12, a lower waveguide layer 13, a low-aluminum active region 14, a high-aluminum electron blocking layer 15, an upper waveguide layer 16, an upper confinement layer 17, and a contact layer 18 arranged sequentially.

[0132] In application, the material of the low-aluminum active region 14 is GaInP or low-aluminum AlGaInP (aluminum content < 0.4%). The low-aluminum active region 14 includes a strain compensation structure, which comprises multiple alternating layers of compressive strain quantum well layers 142 and tensile strain barrier layers 141. The alternation cycle of the compressive strain quantum well layers 142 and tensile strain barrier layers 141 is 3 to 5. The compressive strain quantum well layers 142 are GaInP well layers, and the tensile strain barrier layers 141 are low-aluminum AlGaInP layers (aluminum content < 0.4%).

[0133] In practical applications, the material of the high-aluminum electron blocking layer 15 is AlGaInP with a high aluminum content (aluminum content > 0.8%).

[0134] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An in-situ interface treatment method for an aluminum-based quantum well laser, characterized in that, In a metal-organic chemical vapor deposition apparatus, after growing a low-aluminum active region with a strain-compensated structure and before growing a high-aluminum electron blocking layer, the following steps are included: Step A: Under a V-group source atmosphere, the substrate temperature is maintained at a first temperature for a first time; wherein the first temperature is higher than the growth temperature of the low-aluminum active region and lower than the nucleation temperature of the high-aluminum material, and the first time is 10 seconds to 60 seconds. Step B: Under a V-group source atmosphere, the substrate temperature is lowered from the first temperature to the third temperature, and an aluminum source is introduced to perform strain surface pre-adsorption. Step C: At the third temperature and in a Group V source atmosphere, an aluminum source and other Group III sources besides the aluminum source are introduced to grow a high-alumina nucleation layer; Step D: Raise the substrate temperature from the third temperature to the fourth temperature for annealing. After annealing, grow the main body of the high-aluminum electron blocking layer at the fourth temperature. Step A includes: Step a1: Under a V-group source atmosphere, maintain the substrate temperature at a first temperature for a first time; wherein, the first temperature includes T low +30℃≤T1≤T low +80℃, where T1 is the first temperature, T low This is the growth temperature for the low-aluminum active region; Step a2: When the duration of step a1 is 1 / 2 times the first time, an organosilane precursor is introduced into the reaction chamber of the metal-organic chemical vapor deposition equipment; wherein the introduction time of the organosilane precursor is 2 seconds to 10 seconds. In step a1, the group V source is phosphine, and the flow rate of the group V source is 1.5 to 3 times that of the group V source flow rate when growing the AlGaInP layer. The organosilane precursor is selected from one of tert-butylsilane, diethylsilane and trimethylsilane, and the flow rate of the organosilane precursor is 0.5% to 2% of the flow rate of the group V source in step a1.

2. The in-situ interface processing method according to claim 1, characterized in that, Step B includes: Step b1: When the duration of step a1 is the first time, the substrate is cooled from the first temperature to the second temperature under the atmosphere of group V source and organosilane precursor; wherein the temperature difference between the second temperature and the first temperature is less than or equal to 50°C. Step b2: When the substrate temperature is the second temperature, stop the introduction of organosilane precursor, and under the V-source atmosphere, lower the substrate temperature from the second temperature to the third temperature, and introduce an aluminum source for strain surface pre-adsorption.

3. The in-situ interface processing method according to claim 2, characterized in that, In step B, the substrate is cooled at a rate of 5°C / second to 15°C / second. The third temperature is 500°C to 580°C; In step b2, the flow rate of the aluminum source is 1 / 10 to 1 / 3 of the flow rate of the aluminum source when growing the AlGaInP layer; the pre-adsorption time of the strained surface is 2 to 10 seconds. In step b2, the aluminum source is trimethylaluminum.

4. The in-situ interface processing method according to claim 1, characterized in that, In step C: The group V source is phosphine, and the flow rate of the group V source in step C is 1.5 to 3 times that of the group V source flow rate during the growth of the AlGaInP layer. The ratio of the flow of Group V sources to the flow of all Group III sources is 300:1 to 500:1; The aluminum source is trimethylaluminum; Other Group III sources besides aluminum include trimethylgallium and trimethylindium; The target thickness of the high-aluminum nucleation layer is 2 to 5 nanometers.

5. The in-situ interface processing method according to claim 1, characterized in that, Step D includes: Step d1: After growing the high-aluminum nucleation layer, all group III sources are turned off, the substrate temperature is maintained at the third temperature, and silane is introduced at the same time under the group V source atmosphere to form a silicon passivation layer. Step d2: Under a carrier gas atmosphere, the substrate is heated from the third temperature to the fourth temperature, and during the heating process, steps d21 and d22 are repeated. Step d21: Turn off the growth pulse gas and introduce a reducing pulse gas for 100 to 300 milliseconds; the reducing pulse gas is phosphine; the growth pulse gas includes trimethylaluminum and triethylaluminum, and the flow rate ratio of trimethylaluminum to triethylaluminum is 1:4; Step d22: Turn off the reducing pulse gas, introduce the closed growth pulse gas, and continue for 50 milliseconds to 150 milliseconds; Step d3: When the substrate is at the fourth temperature, the main body of the high-aluminum electron blocking layer is grown in a group III source and a group V source atmosphere.

6. The in-situ interface processing method according to claim 5, characterized in that, Step d1 includes: Step d11: After growing the high-aluminum nucleation layer, turn off all group III sources and maintain the substrate temperature at the third temperature in the group V source atmosphere for 5 to 10 seconds; wherein, the flow rate of the group V source in step d11 is 1.5 to 3 times that of the group V source flow rate when growing the AlGaInP layer. Step d12: In a group V source atmosphere, silane is simultaneously introduced for a duration of 1 to 3 seconds; wherein, the flow rate of silane in step d12 is 0.01% to 0.1% of the flow rate of group V source in step d11.

7. The in-situ interface processing method according to claim 5, characterized in that, The aluminum content in the high-alumina material is >0.8%. The main body and the high-aluminum nucleation layer together constitute the high-aluminum electron blocking layer, wherein the aluminum composition of the high-aluminum nucleation layer is higher than that of the main body. The fourth temperature is 680°C to 720°C; The flow rate of the growth pulse gas is 1 / 20 to 1 / 10 of the aluminum source flow rate during continuous growth of the high-alumina electron blocking layer; In step d21, the ratio of the flow rate of the group V source to the flow rate of the group III source in the gas phase boundary layer of the strained surface is greater than 1000. The carrier gas is hydrogen or deuterium; In step d3, the group V source is phosphine, and the group V source flow rate is the group V source flow rate during the growth of the AlGaInP layer. In step d3, the ratio of the flow rate of the V-source to the flow rate of the III-source is 100 to 200. In step d3, the group III source includes an aluminum source, a gallium source, and an indium source; wherein the aluminum source is trimethylaluminum, the gallium source is trimethylgallium, and the indium source is trimethylindium; In step D, the heating rate is from 10°C / second to 25°C / second.

8. An aluminum-based quantum well laser prepared by an in-situ interface treatment method according to any one of claims 1 to 7, characterized in that, It includes a substrate, a lower confinement layer, a lower waveguide layer, a low-aluminum active region, a high-aluminum electron blocking layer, an upper waveguide layer, an upper confinement layer, and a contact layer arranged sequentially. The low-aluminum active region includes a strain compensation structure, which comprises multiple alternating layers of compressive strain quantum wells and tensile strain barrier layers.

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