Nitride semiconductor laser and single crystal preparation method thereof

Abstract

The embodiment of the invention provides a nitride semiconductor laser and a single crystal preparation method thereof. The laser sequentially comprises a substrate, a lower coating layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper coating layer from bottom to top, a first light absorption loss suppression layer is arranged between the lower coating layer and the lower waveguide layer, and a second light absorption loss suppression layer is arranged between the upper coating layer and the upper waveguide layer. The first light absorption loss suppression layer and the second light absorption loss suppression layer constitute a light absorption loss suppression layer. The first light absorption loss inhibition layer and the second light absorption loss inhibition layer comprise any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, SiC, Ga2O3, BN and diamond.

Description

Technical Field

[0001] This specification relates to the field of semiconductor optoelectronic devices, and in particular to a nitride semiconductor laser and a method for preparing its single crystal. Background Technology

[0002] Lasers are widely used in laser displays, laser TVs, laser projectors, communications, medical applications, weaponry, guidance, ranging, spectral analysis, cutting, precision welding, and high-density optical storage. There are many types of lasers, and they can be classified in various ways, mainly including solid-state, gas, liquid, semiconductor, and dye lasers. Compared with other types of lasers, all-solid-state semiconductor lasers have advantages such as small size, high efficiency, light weight, good stability, long lifespan, simple and compact structure, and miniaturization.

[0003] There are significant differences between lasers and nitride semiconductor light-emitting diodes (LEDs): 1) Lasers generate light through stimulated emission of charge carriers, resulting in a narrow half-width at half-maximum (FW) of the spectrum and very high brightness; a single laser can achieve output power in the W range. In contrast, nitride semiconductor LEDs emit light spontaneously, with a single LED achieving output power in the mW range; 2) Lasers operate at current densities reaching kA / cm². 2 The efficiency of LEDs is more than two orders of magnitude higher than that of nitride LEDs, which may lead to stronger electron leakage, more severe Auger recombination, stronger polarization effect, and more severe electron-hole mismatch, resulting in more severe efficiency degradation and the Droop effect; 3) LEDs emit spontaneous transition radiation without external influence, producing incoherent light from high energy levels to low energy levels, while lasers emit stimulated transition radiation, where the energy of the induced photon must be equal to the energy difference of the electron transition, producing coherent light between the photon and the induced photon; 4) The principles are different: LEDs emit radiative recombination light under the action of external voltage, where electrons and holes transition to quantum wells or pn junctions, while lasers require lasing conditions to be met, which must satisfy the inversion distribution of charge carriers in the active region. The stimulated emission light oscillates back and forth in the resonant cavity, and the propagation in the gain medium amplifies the light. When the threshold condition is met, the gain is greater than the loss, and finally, laser light is output.

[0004] Nitride semiconductor lasers have the following problems: internal optical absorption losses include impurity absorption loss, carrier absorption loss, waveguide sidewall scattering loss, and quantum well absorption loss; high impurity absorption loss in optical waveguides; inherent carbon impurities in p-type semiconductors can compensate for acceptors and destroy p-type properties; low ionization rate of p-type doping (below 10%); a large number of unionized Mg acceptor impurities (above 90%) will produce a self-compensation effect and cause an increase in internal optical loss, resulting in a decrease in laser slope efficiency and an increase in threshold current.

[0005] Therefore, it is necessary to provide a nitride semiconductor laser and its single crystal preparation method, which can improve quantum confinement efficiency and stimulated emission efficiency, reduce the probability of non-radiative recombination such as Auger recombination, thereby reducing the internal optical loss of quantum well absorption loss and improving photoelectric conversion efficiency. Summary of the Invention

[0006] This specification provides one or more embodiments of a nitride semiconductor laser. The laser, from top to bottom, comprises a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper cladding layer, wherein: a first optical absorption loss suppression layer is provided between the lower cladding layer and the lower waveguide layer, and a second optical absorption loss suppression layer is provided between the upper cladding layer and the upper waveguide layer; the first optical absorption loss suppression layer and the second optical absorption loss suppression layer constitute an optical absorption loss suppression layer; the first optical absorption loss suppression layer and the second optical absorption loss suppression layer include any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, SiC, Ga2O3, BN, and diamond.

[0007] One embodiment of this specification provides a method for preparing a single crystal substrate for fabricating a nitride semiconductor laser as described in the embodiments of this specification. The method includes: preparing a single crystal substrate using a multi-step growth process, including: epitaxially growing a seed layer on a sapphire substrate in a metal-organic chemical vapor deposition (MOCVD) reaction chamber; the seed layer comprising multiple layers of GaN, including a GaN buffer layer, a three-dimensional GaN growth layer, and a two-dimensional GaN growth layer; placing the seed layer into a hydride vapor phase epitaxy (HVPE) or chemical vapor deposition (CVD) reaction chamber to grow a single-crystal GaN thick film; and peeling off the seed layer from the sapphire substrate using stress self-separation or laser ablation techniques to form a GaN single-crystal substrate.

[0008] One embodiment of this specification provides a single-crystal fabrication method for preparing a nitride semiconductor laser as described in the embodiments of this specification. The method includes: passing the single-crystal substrate into a MOCVD (Metal-Organic Chemical Vapor Deposition) reaction chamber; performing single-crystal growth of the lower cladding layer using MOCVD; growing a first optical absorption loss suppression layer on the lower cladding layer using MOCVD; growing a lower waveguide layer, an active layer, and an upper waveguide layer above the first optical absorption loss suppression layer using MOCVD; growing a second optical absorption loss suppression layer above the upper waveguide layer using MOCVD; and growing the upper cladding layer above the second optical absorption loss suppression layer using MOCVD, thereby preparing a nitride semiconductor laser with an optical absorption loss suppression layer. Attached Figure Description

[0009] This specification will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein:

[0010] Figure 1 This is a schematic diagram of the structure of a nitride semiconductor laser according to some embodiments of this specification;

[0011] Figure 2 This is a SIMS secondary ion mass spectrum of a nitride semiconductor laser according to some embodiments of this specification;

[0012] Figure 3 This is an exemplary flowchart of a single crystal preparation method according to some embodiments of this specification;

[0013] Figure 4 This is an exemplary flowchart of another single crystal preparation method according to some embodiments of this specification. Detailed Implementation

[0014] To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0015] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one way to distinguish different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0016] As indicated in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0017] Flowcharts are used in this specification to illustrate the operations performed by the system according to embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0018] Figure 1 This is a schematic diagram of the structure of a nitride semiconductor laser according to some embodiments of this specification.

[0019] In some embodiments, such as Figure 1 As shown, the nitride semiconductor laser system 100 may include, from bottom to top, a substrate 100, a lower cladding layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, and an upper cladding layer 105.

[0020] The substrate 100 is the main substrate of the laser, and the substrate 100 is used for growing the various layers of materials of the semiconductor laser. In some embodiments, the substrate 100 may include a semiconductor substrate or a composite substrate.

[0021] In some embodiments, the substrate may be a single-crystal substrate, including any one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, sapphire / SiNx, sapphire / SiO2 / SiNx composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2, and LiGaO2 composite substrate.

[0022] In the embodiments of this specification, the single crystal substrate has advantages such as low defect density, high mobility, and high thermal conductivity. By selecting a substrate 100 with a suitable material, the quality of the laser can be guaranteed to meet different application scenarios.

[0023] The lower cladding layer 101 and the upper cladding layer 105 are functional layers surrounding the waveguide layer, used to confine the optical field and charge carriers, and to ensure efficient laser generation and transmission.

[0024] In some embodiments, the lower cladding layer 101 and the upper cladding layer 105 include any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond.

[0025] In some embodiments, the thickness of the lower cladding layer 101 and the upper cladding layer 105 is 10 angstroms to 90,000 angstroms.

[0026] In some embodiments, the materials or thicknesses of the lower covering layer 101 and the upper covering layer 105 may be the same or different.

[0027] The lower waveguide layer 102 and the upper waveguide layer 104 are functional layers surrounding the active layer, used to guide and regulate the optical field distribution, ensuring that the optical energy is efficiently concentrated in the active region to achieve stimulated emission amplification.

[0028] In some embodiments, the lower waveguide layer 102 and the upper waveguide layer 104 include any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond.

[0029] In some embodiments, the thickness of the lower waveguide layer 102 and the upper waveguide layer 104 is 10 angstroms to 9000 angstroms.

[0030] In some embodiments, the materials or thicknesses of the lower waveguide layer 102 and the upper waveguide layer 104 may be the same or different.

[0031] The active layer 103 refers to the light-emitting region of the laser. Electrons and holes entering the active layer are confined within the active layer due to the heterojunction barrier, resulting in a population inversion distribution. These population-inverted electrons in the active layer can generate spontaneous emission light when they recombine with holes after transitions.

[0032] In some embodiments, the active layer 101 is a periodic structure composed of a well layer and a barrier layer, and the number of periods m satisfies 1 ≤ m ≤ 3. For example, if the number of periods m is 1, it indicates that the active layer 101 is a single-period structure. As another example, if the number of periods m is 2 or 3, it indicates that the active layer 101 is a multi-period structure.

[0033] In some embodiments, the active layer 103 is a quantum well with a periodic structure composed of a well layer and a barrier layer. The quantum well can be periodically arranged with alternating well layers and barrier layers. Under the action of an external electric field, electrons in the quantum well jump from a low-energy band material (e.g., the barrier layer) to a high-energy band material (e.g., the well layer), releasing energy. This energy is converted into photons, thereby generating laser light.

[0034] In some embodiments, the well layer may include any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond.

[0035] In some embodiments, the thickness of the well layer is 10 Å to 100 Å. In some embodiments, the thickness of the well layer may also be one of 10 Å to 80 Å, 10 Å to 50 Å, 20 Å to 100 Å, 20 Å to 80 Å, 40 Å to 100 Å, etc.

[0036] In some embodiments, the barrier layer may include any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond.

[0037] In some embodiments, the thickness of the barrier layer is 10 Å to 150 Å. In some embodiments, the thickness of the barrier layer may also be one of 10 Å to 120 Å, 10 Å to 100 Å, 30 Å to 150 Å, 50 Å to 150 Å, 30 Å to 120 Å, 30 Å to 100 Å, etc.

[0038] In the embodiments of this specification, by selecting appropriate materials for the lower cladding layer 101, lower waveguide layer 102, active layer 103, upper waveguide layer 104 and upper cladding layer 105 to form a laser, and selecting a periodic structure composed of a well layer and a barrier layer as the active layer 103, the laser can have advantages such as high-performance light emission and strong environmental adaptability.

[0039] The structure of a conventional laser element, from bottom to top, includes a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper cladding layer. The structure of the laser element in the embodiments of this specification, from bottom to top, includes a substrate, a lower cladding layer, a first optical absorption loss suppression layer, a lower waveguide layer, an active layer, an upper waveguide layer, a second optical absorption loss suppression layer, and an upper cladding layer.

[0040] In some embodiments, a first optical absorption loss suppression layer 106a may be provided between the lower cladding layer 101 and the lower waveguide layer 102, and a second optical absorption loss suppression layer 106b may be provided between the upper cladding layer 105 and the upper waveguide layer 104. The first optical absorption loss suppression layer 106a and the second optical absorption loss suppression layer 106b may constitute an optical absorption loss suppression layer 106.

[0041] The optical absorption loss suppression layer 106 refers to a functional layer in a laser that minimizes non-radiative absorption loss, thereby improving the light extraction efficiency of the device. The optical absorption loss suppression layer 106 is located at a critical interface in the light propagation path, such as between the waveguide layer and the cladding layer.

[0042] In some embodiments, the first light absorption loss suppression layer 106a and the second light absorption loss suppression layer 106b may include any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, SiC, Ga2O3, BN, and diamond. In some embodiments, the thickness of the first light absorption loss suppression layer 106a and the second light absorption loss suppression layer 106b may be 10 nm to 200 nm.

[0043] In some embodiments, the radiative recombination coefficient of the first optical absorption loss suppression layer is v1, and the radiative recombination coefficient of the second optical absorption loss suppression layer is w1, where: 5*10 -13 (cm 3 / s)≤w1≤v1≤5*10 -9 (cm 3 / s). The radiative recombination coefficient of the first light absorption loss suppression layer is greater than or equal to the radiative recombination coefficient of the second light absorption loss suppression layer.

[0044] The radiative recombination coefficient is a parameter that quantifies the radiative recombination efficiency (i.e., luminous efficiency). It quantitatively reflects the rate of radiative recombination and directly affects the optical output performance and loss characteristics of a device.

[0045] In some embodiments, the radiative recombination coefficient of the first light absorption loss suppression layer and the second light absorption loss suppression layer satisfies: 5*10 -12 (cm 3 / s)≤w1≤v1≤5*10 -9 (cm 3 / s), 5*10 -13 (cm 3 / s)≤w1≤v1≤5*10 -10 (cm 3 / s) or 5*10 -13 (cm 3 / s)≤w1≤v1≤5*10 -9 (cm 3 One of the following: / s). For example, the radiative recombination coefficient of the first or second optical absorption loss suppression layer can be 5*10. -13 (cm 3 / s), 5*10 -12 (cm 3 / s), 5*10 -11 (cm 3 / s), 5*10 -10 (cm 3 / s), 5*10 -9 (cm 3 One of them, such as / s).

[0046] In some embodiments, the radiative recombination coefficient distribution of the first optical absorption loss suppression layer conforms to the first radiation function y = A1 + B1*x -a1 The distribution of the radiative recombination coefficient of the second optical absorption loss suppression layer conforms to the curve distribution of the second radiative function y = C1 + D1 * lnx. Here, a1 > 1 and is an odd number, representing the attenuation rate of the radiative recombination coefficient as x changes. A1, B1, C1, and D1 are constants: A1 represents the background value or asymptotic lower limit of the radiative recombination coefficient; B1 represents the contribution of spatial dependence to radiative recombination; C1 represents the reference value or initial reference value of the radiative recombination coefficient; and D1 represents the sensitivity or modulation intensity of the radiative recombination coefficient as lnx changes. x is a variable representing the thickness from the lower cladding layer to the lower waveguide layer (corresponding to the first radiative function) or the thickness between the upper cladding layer and the upper waveguide layer (corresponding to the second radiative function), and the unit can be angstroms.

[0047] The third quadrant curve distribution refers to the distribution of curves or data points located in the third quadrant (x < 0 and y < 0) in a two-dimensional coordinate system. A third quadrant curve distribution of the first radiation function indicates that x < 0 and y < 0 in the first radiation function.

[0048] In some embodiments, if A1 = 0 and B1 = 1, then the first radiation function can be expressed as y = x -a1 In some embodiments, if C1 = 0 and D1 = 1, the second radiation function can be expressed as y = lnx.

[0049] In the embodiments of this specification, by controlling the radiative recombination coefficient and its distribution of the light absorption loss suppression layer, the quantum confinement efficiency and stimulated emission efficiency can be improved, and the probability of non-radiative recombination such as Auger recombination can be reduced, thereby reducing the internal optical loss of quantum well absorption loss and improving photoelectric conversion efficiency.

[0050] In some embodiments, the hole mobility of the first light absorption loss suppression layer is t1, and the hole mobility of the second light absorption loss suppression layer is u1, where: 5 (cm 2 / V / s)≤u1≤t1≤5000(cm 2 / V / s). The hole mobility of the first light absorption loss suppression layer is greater than or equal to the hole mobility of the second light absorption loss suppression layer.

[0051] Hole mobility is a parameter that measures the efficiency of hole transport in an optical absorption loss suppression layer. Hole mobility affects the current distribution, heat dissipation, and optical absorption suppression effect of the device. High mobility means that holes move faster in the electric field, resulting in lower resistance and reducing Joule heating and carrier accumulation.

[0052] In some embodiments, the hole mobility of the first light absorption loss suppression layer and the second light absorption loss suppression layer satisfies: 10 (cm²) 2 / V / s)≤u1≤t1≤5000(cm 2 / V / s), 100 (cm) 2 / V / s)≤u1≤t1≤5000(cm 2 / V / s), 5 (cm) 2 / V / s)≤u1≤t1≤3000(cm 2 / V / s) or 5 (cm) 2 / V / s)≤u1≤t1≤1000(cm 2 One of / V / s, etc. For example, the hole mobility of the first or second light absorption loss suppression layer can be 5 (cm²). 2 / V / s), 50 (cm) 2 / V / s), 500 (cm) 2 / V / s), 2500 (cm)2 / V / s), 5000 (cm) 2 One of them, such as / V / s).

[0053] In some embodiments, the hole mobility distribution of the first optical absorption loss suppression layer conforms to a first mobility function y = E1 + F1*x -b1 The curve distribution of the first mobility function is in the third quadrant, and the hole mobility distribution of the second optical absorption loss suppression layer conforms to the curve distribution of the second mobility function y = L1 + M1 * lnx. Here, b1 > 1 and is an odd number, representing the decay rate of hole mobility with respect to x. E1, F1, L1, and M1 are constants. E1 represents the background value of hole mobility or the asymptotic value in the high x region, F1 represents the modulation intensity of hole mobility by spatial or field-dependent effects, L1 represents the baseline value or initial reference value of hole mobility, and M1 represents the sensitivity or modulation intensity of hole mobility with respect to lnx. In the first mobility function, x < 0 and y < 0. x is a variable representing the thickness from the lower cladding layer to the lower waveguide layer (corresponding to the first mobility function) or the thickness between the upper cladding layer and the upper waveguide layer (corresponding to the second mobility function), and the unit can be angstroms.

[0054] In some embodiments, if E1 = 0 and F1 = 1, then the first mobility function can be expressed as y = x -b1 In some embodiments, if L1 = 0 and M1 = 1, then the second mobility function can be expressed as y = lnx.

[0055] In the embodiments of this specification, by controlling the hole concentration and its distribution injected into the active layer, the energy of the injected hole carriers is quantized and the sub-bands are filled step by step. This can improve the matching degree of the electron-hole wave function of the active layer, improve the utilization rate of electrons and holes injected into the active layer, reduce the internal optical loss of carrier absorption loss, increase the differential gain, accelerate the population inversion of the laser, and reduce the threshold current density.

[0056] In some embodiments, the density of the first light absorption loss suppression layer is r, and the density of the second light absorption loss suppression layer is s, where: 1 (g / cm³) 3 )≤s≤r≤30(g / cm 3 The density of the first light absorption loss suppression layer is greater than or equal to the density of the second light absorption loss suppression layer.

[0057] Density is a quantitative parameter representing the carrier concentration (electrons and holes) or defect state density in the optical absorption loss suppression layer. Density can be used to minimize non-radiative absorption losses while maintaining necessary electrical performance.

[0058] In some embodiments, the densities of the first light absorption loss suppression layer and the second light absorption loss suppression layer satisfy: 1 ​​(g / cm³)3 )≤s≤r≤20(g / cm 3 ), 1 (g / cm 3 )≤s≤r≤15(g / cm 3 ), 3 (g / cm 3 )≤s≤r≤30(g / cm 3 ) or 10 (g / cm 3 )≤s≤r≤30(g / cm 3 One of the following, etc. For example, the density of the first or second light absorption loss suppression layer can be 1 g / cm³. 3 ), 10 (g / cm 3 ), 15 (g / cm 3 ), 20 (g / cm 3 ), 30 (g / cm 3 One of them, etc.

[0059] In some embodiments, the density distribution of the first light absorption loss suppression layer has a first density function y = G1 + H1*x -c1 The density distribution of the second optical absorption loss suppression layer follows a curve distribution with the third quadrant for the first density function, and the second density distribution follows a curve distribution with the second density function y = J1 + K1 * lnx. Here, c1 > 1 and is an odd number, representing the attenuation rate of density as x changes. G1, H1, J1, and K1 are constants; G1 represents the background or asymptotic value of the density, H1 represents the spatial or concentration-dependent modulation term of the density distribution, J1 represents the baseline or initial reference value of the density, and K1 represents the sensitivity or modulation intensity of the density as lnx changes. In the first density function, x < 0 and y < 0. x is a variable representing the thickness from the lower cladding layer to the lower waveguide layer (corresponding to the first density function) or the thickness between the upper cladding layer and the upper waveguide layer (corresponding to the second density function), and the unit can be angstroms.

[0060] In some embodiments, if G1 = 0 and H1 = 1, then the first density function can be expressed as y = x. -c1 In some embodiments, if J1 = 0 and K1 = 1, then the second density function can be expressed as y = lnx.

[0061] In some embodiments, the radiative recombination coefficient distribution, hole mobility distribution, and density distribution of the first optical absorption loss suppression layer have the following relationship: 0 < b1 < c1 < a1 < 100. For example, a1 = 99, b1 = 1, c1 = 51.

[0062] In the embodiments of this specification, by adjusting the laser density distribution, the steepness of the interface can be increased, the interface state density of the waveguide layer interface can be reduced, the internal optical loss of the waveguide structure sidewall scattering loss can be reduced, and the photoelectric conversion efficiency can be improved.

[0063] In some embodiments, the light absorption coefficient of the first light absorption loss suppression layer is m1, and the light absorption coefficient of the second light absorption loss suppression layer is n1, where 0.2*10 5 (cm -1 )≤m1≤n1≤3*10 5 (cm -1 The light absorption coefficient of the first light absorption loss suppression layer is less than or equal to the light absorption coefficient of the second light absorption loss suppression layer.

[0064] The light absorption coefficient is a physical quantity that describes the attenuation of light due to absorption as it propagates through a material. The light absorption coefficient directly reflects the degree of light loss suppression by the light absorption loss suppression layer and can be used to evaluate the performance of such layers.

[0065] In some embodiments, the light absorption coefficients of the first light absorption loss suppression layer and the second light absorption loss suppression layer satisfy: 0.2*10 5 (cm -1 )≤m1≤n1≤2*10 5 (cm -1 ), 0.5*10 5 (cm -1 )≤m1≤n1≤3*10 5 (cm -1 ), 1*10 5 (cm -1 )≤m1≤n1≤3*10 5 (cm -1 ) or 0.2*10 5 (cm -1 )≤m1≤n1≤2*10 5 (cm -1 One of the following: (e.g., the first or second light absorption loss suppression layer). For example, the light absorption coefficient of the first or second light absorption loss suppression layer can be 0.2*10. 5 (cm -1 ), 1*10 5 (cm -1 ), 1.6*10 5 (cm -1 ), 2*10 5 (cm -1 ), 3*10 5 (cm -1 One of them, etc.

[0066] In some embodiments, the light absorption coefficient of the first light absorption loss suppression layer conforms to the first light absorption function y = N1 + P1 * d1 x The curve distribution shows that the light absorption coefficient distribution of the second light absorption loss suppression layer conforms to the second light absorption function y = Q1 + R1 * g1.x The curve distribution is shown. Where 0 < g1 < 1 < d1, d1 represents the attenuation rate of the optical absorption coefficient as x changes, and g1 represents the attenuation rate of the absorption coefficient as x changes. N1, P1, Q1, and R1 are constants. N1 represents the background value or minimum asymptotic value of the optical absorption coefficient, P1 represents the modulation amplitude or enhancement term intensity of the optical absorption coefficient, Q1 represents the reference value or background absorption term of the optical absorption coefficient, and R1 represents the modulation amplitude or enhancement / suppression term intensity of the optical absorption coefficient. For example, g1 = 0.5, d1 = 3. x is a variable representing the thickness from the lower cladding layer to the lower waveguide layer (corresponding to the first optical absorption function) or the thickness between the upper cladding layer and the upper waveguide layer (corresponding to the second optical absorption function), and the unit can be angstroms.

[0067] In some embodiments, if N1 = 0 and P1 = 1, then the first density function can be expressed as y = d1. x In some embodiments, if Q1 = 0 and R1 = 1, then the second density function can be expressed as y = g1. x .

[0068] In the embodiments of this specification, by controlling the light field distribution of the laser, the longitudinal diffusion of the light field can be reduced, the absorption loss of the light field by the unionized Mg acceptors in the electron blocking layer and the upper cladding layer can be isolated, the recombination of charge carriers with interface states and surface states of the heterojunction can be reduced, the internal optical loss of the laser can be suppressed, the threshold current can be reduced, and the photoelectric conversion efficiency of the laser can be improved.

[0069] In some embodiments, the nitride semiconductor lasers described in this specification can be tested using laser chip testing equipment. The laser is designed with a ridge width of 45µm and a cavity length of 1200µm. The test current is 0-4A pulsed or continuous mode, and the test environment temperature is 25°C. The laser's optical power signal is collected using an integrating sphere to test the photoelectric conversion efficiency (which can be represented by wall-plug efficiency, WPE), thermal decay, internal optical loss, and threshold current density. Thermal decay refers to the significant decrease in optical output power of an optoelectronic device due to increased temperature during continuous operation or in high-temperature environments; it is a short-term, reversible decrease. Threshold current density is the minimum current density at which the laser begins lasing. Lashing refers to the physical phenomenon of light output amplification through stimulated emission. Thermal decay testing can include continuous wave (CW) testing; for example, after encapsulating the laser, it is placed in air at an ambient temperature of 25°C, and the power difference between the laser at 60 seconds and 0 seconds is continuously tested without a heat dissipation device.

[0070] As an example only, the test results are shown in Table 1 below. Table 1 Laser Test Results project Traditional lasers The lasers described in this specification range of change Thermal decay (60s CW test) 84％ 36％ -57％ Photoelectric conversion efficiency (WPE) 41％ 53％ 29％ <![CDATA[Internal optical loss (cm -1 )]]> 11.6 7.3 59％ <![CDATA[Threshold current density (kA / cm 2 )]]> 2.13 0.91 -57％

[0071] As can be seen from Table 1, compared with traditional lasers, the lasers in the embodiments of this specification have lower thermal attenuation, indicating better thermal stability. At the same time, the lasers in the embodiments of this specification have higher photoelectric conversion efficiency, lower internal optical loss, and lower threshold current density, exhibiting better performance in many aspects.

[0072] In some embodiments, the upper waveguide layer is a strain-releasing upper waveguide layer; the strain-releasing upper waveguide layer includes any one or any combination of InGaN, GaN, InN, and AlInGaN; the covalent bond energy distribution of the strain-releasing upper waveguide layer conforms to an arc-shaped distribution.

[0073] A strain-releasing waveguide layer refers to a functional layer that balances lattice mismatch stress while maintaining high-efficiency optical waveguide performance through a controllable strain-releasing mechanism. Strain-releasing waveguide layers can alleviate lattice mismatch stress between the active layer and the cladding layer, for example, compressive strain in InGaN / GaN systems.

[0074] In some embodiments, the thickness of the strain-releasing upper waveguide layer is 50 nm to 200 nm.

[0075] Covalent bond energy distribution refers to the spatial or energy distribution of the binding energy of covalent bonds between atoms in a material. The arc-shaped distribution of covalent bond energy in a strain-released waveguide layer indicates a non-uniform bond energy distribution induced by strain gradients. This arc-shaped distribution is characterized by a continuous and gradual change in bond length and bond angle along the growth direction, forming a smooth transition of the energy barrier and avoiding abrupt energy changes at the interface (between the active layer and the cladding layer).

[0076] In the embodiments described in this specification, the strain-releasing upper waveguide layer can achieve a balance between optical field confinement and strain management, reducing threshold current and optical loss to realize high-performance optoelectronic devices.

[0077] In some embodiments, the covalent bond energy distribution of the strain-released upper waveguide layer conforms to the first covalent bond energy function y = A² + B² * log a2 The curve distribution of ((m2+x) / (m2-x)) is given, with the first covalent bond energy function distributed in the second quadrant. Here, 0 < a2 < 1, m2 > 0, A2 and B2 are constants, and x is a variable representing the thickness of the upper waveguide layer, in units of angstroms. For example, a2 = 0.5, m2 = 1.

[0078] The second quadrant curve distribution refers to the distribution of curves or data points located in the second quadrant (x < 0 and y > 0) in a two-dimensional coordinate system. The second quadrant curve distribution of the first covalent bond energy function represents the distribution of the first covalent bond energy function where x < 0 and y > 0.

[0079] In some embodiments, if A2 = 0 and B2 = 1, then the first covalent bond energy function can be expressed as y = log a2 ((m2+x) / (m2-x)).

[0080] In some embodiments, the density distribution of the strain-released waveguide layer conforms to an arc-shaped distribution; the density distribution of the strain-released waveguide layer conforms to the third density function y = C² + D² * log. b2 The distribution of the density function ((n²+x) / (n²-x)) is represented by a curve, with the third density function distributed in the third quadrant. Here, b² > 1, n² > 0, where b² represents the scale of the logarithmic transformation, and n² represents the saturation threshold of the strain or spatial variable. C² and D² are constants; C² represents the baseline or center of symmetry value of the density, and D² represents the sensitivity of the density to strain or spatial inhomogeneity, or the modulation intensity. For example, b² = 3, n² = 1. x is a variable representing the thickness of the upper waveguide layer, which can be in angstroms.

[0081] An arc-shaped density distribution indicates that the atomic density (or carrier concentration, defect density) in the strain-releasing waveguide layer exhibits a non-linear, gradual change along the growth direction, forming a parabolic spatial distribution. This arc-shaped density distribution avoids interface stress concentration, maximizes strain-releasing efficiency, and enhances optical field manipulation capabilities.

[0082] In some embodiments, if C2 = 0 and D2 = 1, then the third density function can be expressed as y = log b2 ((n2+x) / (n2-x)).

[0083] In some embodiments, the optical absorption coefficient distribution of the strain-released upper waveguide layer conforms to an arc-shaped distribution, and the optical absorption coefficient distribution of the strain-released upper waveguide layer conforms to the third optical absorption function y = E² + F² * log. c2 The distribution of the optical absorption coefficient ((p2+x) / (p2-x)) curve is shown, with the third optical absorption function distributed in the second quadrant. Here, 0 < c2 < 1, p2 > 0, where c2 represents the scale of the logarithmic transformation, and p2 represents the saturation threshold of strain or external variables. E2 and F2 are constants; E2 represents the reference value or center of symmetry value of the optical absorption coefficient, and F2 represents the sensitivity of the optical absorption coefficient to strain or external variables, or the modulation intensity. For example, c2 = 0.5, p2 = 1. x is a variable representing the thickness of the upper waveguide layer, which can be in angstroms.

[0084] An arc-shaped distribution of the optical absorption coefficient indicates that the absorption coefficient of the waveguide layer under strain release exhibits a nonlinear gradual change along the growth direction. This typically manifests as a "concave arc" (lower in the middle and higher on both sides) or a reverse "convex arc" distribution. By synergistically modulating the strain field and optical field transmission, the arc-shaped optical absorption coefficient can significantly improve the performance of optoelectronic devices.

[0085] In some embodiments, if E2 = 0 and F2 = 1, then the third light absorption function can be expressed as y = log c2 ((p2+x) / (p2-x)).

[0086] In some embodiments, the hole mobility distribution of the strain-released upper waveguide layer conforms to an arc-shaped distribution, and the hole mobility distribution of the strain-released upper waveguide layer conforms to the third mobility function y = G² + H² * e x The curve distribution of / x is shown, and the third mobility function is a curve distribution in the third quadrant. Here, G2 and H2 are constants; G2 represents the background value of hole mobility or the asymptotic value in the high x region, and H2 represents the sensitivity of hole mobility to strain or spatial inhomogeneity, or the modulation intensity. In the third mobility function, x < 0 and y < 0. x is a variable representing the thickness of the upper waveguide layer, which can be in angstroms.

[0087] The arc-shaped hole mobility distribution indicates that the hole mobility in the strain-released waveguide layer exhibits a nonlinear gradual change along the growth direction (z-axis). This arc-shaped hole mobility distribution, through synergistic optimization of carrier transport and strain release, can significantly improve the electro-optical conversion efficiency and thermal stability of optoelectronic devices.

[0088] In some embodiments, if G2 = 0 and H2 = 1, then the third density function can be expressed as y = e x / x.

[0089] In some embodiments, the covalent bond energy distribution, density distribution, and optical absorption coefficient distribution of the strain-released waveguide layer have the following relationship: 0 < a2 ≤ c2 < 1 < b2. For example, a2 = 0.3, c2 = 0.5, b2 = 3.

[0090] In some embodiments, a laser chip testing device is used to test the nitride semiconductor lasers of the embodiments in this specification. The tests include aging-induced optical decay, thermal decay, photoelectric conversion efficiency, and internal optical loss. Aging-induced optical decay refers to the gradual decrease in optical output power of an optoelectronic device during long-term operation due to material degradation, structural damage, or environmental factors. Thermal decay refers to the irreversible degradation of the performance of an optoelectronic device under high temperature or long-term operation, including material or structural damage. Thermal decay testing may include isothermal aging testing, temperature cycling testing, and high-temperature and high-humidity testing, with a test duration of 5 minutes. Aging-induced optical decay testing may include accelerated aging testing, with a test duration of 1000 hours.

[0091] As an example only, the test results are shown in Table 2 below. Table 2 Laser Test Results Laser - Project Traditional lasers The lasers described in this specification range of change 1000H aging and light decay 22％ 4％ -84％ Thermal decay (5-minute test) 91％ 26％ -71％ Photoelectric conversion efficiency 34.50％ 43.70％ 27％ <![CDATA[Internal optical loss (cm -1 )]]> 17.2 13.4 -22％

[0092] As can be seen from Table 2, compared with traditional lasers, the lasers in the embodiments of this specification have lower aging light decay, lower thermal decay, higher photoelectric conversion efficiency, and lower internal optical loss, and have better performance in many aspects.

[0093] In the embodiments of this specification, the covalent bond energy distribution of the strain-released upper waveguide layer has a first covalent bond energy function, and the density distribution of the strain-released upper waveguide layer has a third density function, both conforming to an arc-shaped distribution. This can form a strain-released upper waveguide layer, reducing problems such as In clusters and InN segregation in the active layer, achieving a uniform, stable, low-stress, and steeply interfaced InGaN quantum well structure in the active layer. This reduces defects and interface state density in the quantum well, reduces non-radiative recombination centers, and improves the lifetime and reliability of the laser. By controlling the stress distribution throughout the laser structure, spontaneous polarization and piezoelectric polarization effects can be suppressed, as can quantum confinement Stark effects (QCSE). This reduces high-density defects caused by band tilt and stress mismatch during epitaxial growth, reduces defects, thermal decay, and interface state density in the quantum well, and increases the spatial overlap probability of electron-hole wave functions, thereby improving radiative recombination efficiency and reducing optical absorption loss.

[0094] In some embodiments, the upper covering layer 105 includes a first upper covering layer 105a and a second upper covering layer 105b, with an internal light absorption loss suppression layer 107 between the first upper covering layer 105a and the second upper covering layer 105b.

[0095] The internal light absorption loss suppression layer 107 is a functional layer in optoelectronic devices used to minimize parasitic light absorption.

[0096] In some embodiments, the internal light absorption loss suppression layer 107 includes any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond.

[0097] In the embodiments described in this specification, by setting an internal light absorption loss suppression layer and selecting appropriate materials, the materials and structure can be precisely controlled, significantly reducing the light field transmission loss.

[0098] In some embodiments, the angle at which the peak position of the valence band effective density of states in the internal optical absorption loss suppression layer decreases towards the quantum well is α; the angle at which the peak position of the valence band effective density of states in the internal optical absorption loss suppression layer decreases towards the surface is β; the angle at which the peak position of the valence band effective density of states in the first upper cladding layer decreases towards the quantum well is γ; and the angle at which the peak position of the valence band effective density of states in the second upper cladding layer decreases towards the surface is θ, wherein 30°≤α≤β≤γ≤θ≤90°. For example, α=30°, β=45°, γ=60°, θ=90°.

[0099] In some embodiments, the angle at which the valley of the saturated electron drift velocity of the internal optical absorption loss suppression layer rises towards the quantum well is δ, the angle at which the valley of the saturated electron drift velocity of the internal optical absorption loss suppression layer rises towards the surface is σ, and the angle at which the valley of the saturated electron drift velocity of the first upper coating layer rises towards the quantum well is σ. The angle of ascent from the valley of the saturated electron drift velocity of the second upper coating layer towards the surface is ψ, where, For example, δ = 20°, σ = 40°, ψ = 90°.

[0100] In some embodiments, the angle at which the peak position of the deformation potential of the internal light absorption loss suppression layer decreases towards the quantum well is μ, the angle at which the peak position of the deformation potential of the internal light absorption loss suppression layer decreases towards the surface is υ, the angle at which the peak position of the deformation potential of the first upper coating layer decreases towards the quantum well is ρ, and the angle at which the peak position of the deformation potential of the second upper coating layer decreases towards the surface is ω, wherein 10°≤μ≤υ≤ρ≤ω≤90°. For example, μ=10°, υ=30°, ρ=60°, ω=90°.

[0101] In some embodiments, the angle at which the valley of the bulk elastic modulus of the internal light absorption loss suppression layer rises towards the quantum well is ε, the angle at which the valley of the bulk elastic modulus of the internal light absorption loss suppression layer rises towards the surface is η, the angle at which the valley of the bulk elastic modulus of the first upper coating layer rises towards the quantum well is κ, and the angle at which the valley of the bulk elastic modulus of the second upper coating layer rises towards the surface is ζ, wherein 5°≤ε≤η≤κ≤ζ≤90°. For example, ε=5°, η=25°, κ=55°, ζ=90°.

[0102] The angle of ascent and angle of descent refer to the change in the direction of the tangent to the curve at a certain point or the angle between the tangent directions at different points. The angle of ascent and angle of descent can be calculated from the slope of the curve.

[0103] In some embodiments, a laser chip testing device is used to test the nitride semiconductor lasers of the embodiments in this specification. The tests include slope efficiency, threshold current density, optical power, and internal optical loss. Slope efficiency refers to the efficiency of optical power increasing with current after laser lasing, reflecting the efficiency of carrier conversion into photons. Optical power refers to the total output optical power of the laser during continuous operation.

[0104] As an example only, the test results are shown in Table 3 below. Table 3 Laser Test Results Laser - Project Traditional lasers The lasers described in this specification range of change Slope efficiency (W / A) 1.12 1.89 69％ <![CDATA[Threshold current density (kA / cm 2 )]]> 2.4 0.97 -60％ Optical power (W) 4.8 7.12 48％ <![CDATA[Internal optical loss (cm -1 )]]> 17.2 8.47 -51％

[0105] As can be seen from Table 3, compared with traditional lasers, the lasers in the embodiments of this specification have higher slope efficiency, lower threshold current density, higher optical power, and lower internal optical loss, and have better performance in many aspects.

[0106] In the embodiments of this specification, by adjusting the interface change angle of the deformation potential and bulk elastic modulus of the internal light absorption loss suppression layer, the self-compensation effect of Mg can be suppressed, the absorption loss of the upper coating layer on the light field can be reduced, and at the same time, by controlling the interface change angle of the effective density of states of the valence band and the drift rate of saturated electrons, the ionization efficiency and solubility of Mg can be enhanced, the formation energy of Mg-H bonds can be reduced, the hole concentration and injection efficiency can be increased, and the uniformity of the active layer carrier distribution can be improved, thereby improving the luminous efficiency and slope efficiency of the light emitter.

[0107] In some embodiments, 5°≤ε≤η≤μ≤υ≤δ≤σ≤α≤β≤90°. For example, ε=5°, η=30°, μ=40°, υ=50°, δ=60°, σ=70°, α=80°, β=90°.

[0108] In some embodiments, the valence band effective state density distribution of the internal optical absorption loss suppression layer has a valence band effective state density function y = A³ + B³ * lnx - e x The curve distribution; the saturated electron drift velocity distribution of the internal light absorption loss suppression layer has an electron drift velocity function y = C3 + D3*x 2 The curve distribution of +E3*sinx; the deformation potential distribution of the internal light absorption loss suppression layer has a deformation potential function y=F3+H3*lnx-J3*e xThe volumetric elastic modulus distribution of the internal optical absorption loss suppression layer exhibits a curve distribution of the volumetric elastic modulus function y = K3 + L3*x + M3*1 / 2x, with the volumetric elastic modulus function being a curve distribution in the first quadrant. Here, A3, B3, C3, D3, E3, F3, H3, J3, K3, L3, and M3 are constants; A3 represents the baseline value of the effective density of states in the valence band; B3 represents the coefficient of the logarithmic correction term; C3 represents the baseline value of the saturated electron drift velocity; and D3 represents the saturated electron drift velocity as a function of x. 2 The rate of change of E3 represents the coefficient of the periodic modulation term (controlling the amplitude of the sinx term), F3 represents the baseline value of the deformation potential, H3 represents the rate of change of the deformation potential with respect to lnx, and J3 represents the rate of change of the deformation potential with respect to e. x The rate of change of the bulk modulus, where K3 represents the baseline value of the bulk modulus function, L3 represents the linear rate of change of the bulk modulus with respect to spatial coordinate x, and M3 represents the nonlinear rate of change of the bulk modulus. x is a variable representing the thickness between the lower cladding layer and the lower waveguide layer or between the upper cladding layer and the upper waveguide layer, and the unit can be angstroms.

[0109] The first quadrant curve distribution refers to the distribution of curves or data points located in the first quadrant (x>0 and y>0) in a two-dimensional coordinate system. The first quadrant curve distribution of the bulk modulus function represents the distribution of the bulk modulus function where x>0 and y>0.

[0110] The effective state density distribution in the valence band refers to the distribution of quantum states available for hole occupancy in the valence band of a semiconductor as a function of energy.

[0111] In some embodiments, if A3 = 0 and B3 = 1, the valence band effective density of states function can be expressed as y = lnx - e x .

[0112] Electron drift velocity distribution refers to the distribution of the velocity of electrons under the action of an applied electric field.

[0113] In some embodiments, if C3 = 0, D3 = 1, and E3 = 1, the electron drift rate function can be expressed as y = x 2 +sinx.

[0114] Deformation potential distribution refers to the distribution of band edge shift caused by unit lattice strain.

[0115] In some embodiments, if F3 = 0, H3 = 1 and J3 = 1, the deformation potential function can be expressed as y = lnx - e x .

[0116] In some embodiments, if K3 = 0, L3 = 1 and M3 = 1, the bulk modulus function can be expressed as y = x + 1 / 2x.

[0117] In the embodiments of this specification, by adjusting the effective density of valence band states, electron drift rate, deformation potential, and bulk modulus of the internal light absorption loss suppression layer, hole transport can be optimized, Auger recombination can be suppressed, high-frequency performance can be improved, thermal noise can be reduced, non-radiative recombination can be reduced, thermal management can be optimized, crack propagation can be suppressed, and photoelectric efficiency, high-frequency response speed, and thermal stability can be improved.

[0118] Figure 2 This is a SIMS secondary ion mass spectrum of a nitride semiconductor laser according to some embodiments of this specification. The concentration distribution of various elements between different layers can be seen from the SIMS (Secondary Ion Mass Spectrometry) measurements. Figure 2 As shown, the horizontal axis represents the depth of the laser, in μm. From left to right, the layers are: second upper cladding layer 105b, internal optical absorption loss suppression layer 107, first upper cladding layer 105a, second optical absorption loss suppression layer 106b, upper waveguide layer 104, active layer 103, lower waveguide layer 102, first optical absorption loss suppression layer 106a, and lower cladding layer 101. The vertical axis on the left represents the elemental concentration, in atmos / cm³. 3 The right vertical axis represents ionic intensity, in units of au.

[0119] Figure 3 This is an exemplary flowchart of a single crystal preparation method according to some embodiments of this specification. In some embodiments, process 300 may be performed manually. Figure 3 As shown, process 300 includes the following steps.

[0120] In some embodiments, a multi-step method can be used to grow crystals in order to prepare a single-crystal substrate.

[0121] Step 310: Using a sapphire substrate, a seed layer is epitaxially grown in the reaction chamber of metal-organic chemical vapor deposition (MOCVD).

[0122] MOCVD, also known as Metal-Organic Vapor Phase Epitaxy (MOVPE), is a technique for growing high-quality semiconductor single-crystal thin films. MOCVD achieves the epitaxial growth of single-crystal thin films by a chemical reaction between a metal-organic source and a hydride gas on a high-temperature substrate surface.

[0123] In some embodiments, the sapphire substrate can be pretreated before crystal growth, for example, by removing surface contaminants with organic solvents (e.g., acetone, ethanol), acid washing (e.g., a mixture of H2SO4:H3PO4), and deionized water.

[0124] In some embodiments, within the MOCVD reaction chamber, the cleaned sapphire substrate can be annealed at high temperature (e.g., 1000-1100°C) for 5-10 minutes in a hydrogen (H2) or nitrogen (N2) environment to remove the surface oxide layer and achieve atomic-level flatness.

[0125] The seed layer is a key transition layer in semiconductor epitaxial growth, used to provide a lattice-matching template for subsequent functional layers and control defect propagation.

[0126] In some embodiments, the seed layer may include a multilayer GaN, which includes a GaN buffer layer, a GaN three-dimensional growth layer, and a GaN two-dimensional growth layer.

[0127] GaN buffer layers, GaN 3D growth layers, and GaN 2D growth layers refer to functional layers grown using different growth modes. GaN buffer layers can alleviate lattice mismatch between the substrate and GaN, thus improving epitaxial quality. GaN 3D growth layers, formed on top of GaN buffer layers, create a three-dimensional island structure that can absorb thermal mismatch stress, aiding in stress release. GaN 2D growth layers are layered epitaxial layers achieved by optimizing growth conditions after the merging of 3D layers, providing a growth substrate for subsequent functional layers.

[0128] In some embodiments, gallium-containing raw materials (e.g., TMGa, TEGa, TMA, etc.) can be used as gallium sources and hydride gas (e.g., NH3) can be used as nitrogen sources. The gallium source and nitrogen source are reacted under different growth conditions in the MOCVD reaction chamber to generate GaN buffer layers, GaN three-dimensional growth layers and GaN two-dimensional growth layers, respectively.

[0129] In some embodiments, the growth conditions of the GaN buffer layer include: a temperature of 500℃ to 900℃, a pressure of 100 Torr to 500 Torr, and a rotation speed of 600 rpm to 12000 rpm. In some embodiments, the growth conditions of the GaN buffer layer may further include: a temperature of one of 500℃ to 700℃, 700℃ to 900℃, or 600℃ to 800℃; a pressure of one of 100 Torr to 400 Torr, 100 Torr to 300 Torr, or 200 Torr to 400 Torr; and a rotation speed of one of 600 rpm to 10000 rpm, 600 rpm to 8000 rpm, 1000 rpm to 12000 rpm, or 2000 rpm to 12000 rpm. For example, the temperature is one of 500℃, 700℃, 900℃, etc., the pressure is one of 100Torr, 300Torr, 500Torr, etc., and the rotation speed is one of 600 rpm, 6300 rpm, 12000 rpm, etc.

[0130] In some embodiments, the thickness of the GaN buffer layer is 10 nm to 200 nm. In some embodiments, the thickness of the GaN buffer layer may also be one of 10 nm to 200 nm, 10 nm to 150 nm, 10 nm to 100 nm, 50 nm to 200 nm, etc. For example, the thickness of the GaN buffer layer is one of 10 nm, 100 nm, 200 nm, etc.

[0131] In some embodiments, the growth conditions for the GaN three-dimensional growth layer include: a temperature of 900℃ to 1100℃, a pressure of 150 Torr to 500 Torr, and a rotation speed of 600 rpm to 12000 rpm. In some embodiments, the growth conditions for the GaN three-dimensional growth layer may further include: a temperature of one of 900℃ to 1000℃, 950℃ to 1100℃, or 950℃ to 1050℃; a pressure of one of 150 Torr to 400 Torr, 150 Torr to 300 Torr, 200 Torr to 400 Torr, or 200 Torr to 500 Torr; and a rotation speed of one of 600 rpm to 10000 rpm, 600 rpm to 8000 rpm, 1000 rpm to 12000 rpm, or 2000 rpm to 12000 rpm. For example, the temperature is one of 900℃, 1000℃, 1100℃, etc., the pressure is one of 150Torr, 300Torr, 500Torr, etc., and the rotation speed is one of 600 rpm, 6300 rpm, 12000 rpm, etc.

[0132] In some embodiments, the thickness of the GaN three-dimensional growth layer is 200 nm to 5000 nm. In some embodiments, the thickness of the GaN three-dimensional growth layer may also be one of 200 nm to 3000 nm, 200 nm to 5000 nm, 500 nm to 5000 nm, 500 nm to 3000 nm, etc. For example, the thickness of the GaN three-dimensional growth layer is one of 200 nm, 2600 nm, 5000 nm, etc.

[0133] In some embodiments, the growth conditions for the GaN two-dimensional growth layer include: a temperature of 1000℃~1200℃, a pressure of 150Torr~250Torr, and a rotation speed of 600 rpm~12000 rpm. In some embodiments, the growth conditions for the GaN two-dimensional growth layer may further include: a temperature of one of 1000℃~1100℃, 1100℃~1200℃, or 1050℃~1150℃; a pressure of one of 150Torr~200Torr, 200Torr~250Torr, 150Torr~225Torr, or 175Torr~250Torr; and a rotation speed of one of 600 rpm~10000 rpm, 600 rpm~8000 rpm, 1000 rpm~12000 rpm, or 2000 rpm~12000 rpm. For example, the temperature is one of 1000℃, 1100℃, 1200℃, etc., the pressure is one of 150 Torr, 200 Torr, 250 Torr, etc., and the rotation speed is one of 600 rpm, 6300 rpm, 12000 rpm, etc.

[0134] In some embodiments, the thickness of the GaN two-dimensional growth layer is 2000 nm to 10000 nm. In some embodiments, the thickness of the GaN two-dimensional growth layer can also be one of 2000 nm to 8000 nm, 4000 nm to 8000 nm, 4000 nm to 10000 nm, etc. For example, the thickness of the GaN two-dimensional growth layer is one of 2000 nm, 6000 nm, 10000 nm, etc.

[0135] In the embodiments of this specification, by precisely controlling parameters such as temperature, rotation speed and pressure, the quality of GaN buffer layer, GaN three-dimensional growth layer and GaN two-dimensional growth layer can be optimized, thereby improving the crystal quality, surface morphology and electrical or optical properties of epitaxial thin film.

[0136] Step 320: Place the seed crystal layer into a hydride vapor phase epitaxy (HVPE) or chemical vapor deposition (CVD) reaction chamber to grow a single-crystal GaN thick film.

[0137] Single-crystal GaN thick films refer to GaN materials with a single crystal structure prepared by epitaxial growth techniques (e.g., HVPE). Single-crystal GaN thick films can be used as GaN substrates to replace sapphire or SiC substrates for epitaxial growth of device structures.

[0138] In some embodiments, the growth temperature of the single-crystal GaN thick film is 1000℃~1200℃, HCl and GaCl3 are introduced as gallium sources, NH3 is introduced as a nitrogen source, and the thickness of the single-crystal GaN thick film is 5um~500um.

[0139] In some embodiments, the growth temperature of the single-crystal GaN thick film can also be one of 1000℃~1100℃, 1100℃~1200℃, 1050℃~1150℃, etc. For example, the growth temperature of the single-crystal GaN thick film can be one of 1000℃, 1100℃, 1200℃, etc.

[0140] In some embodiments, the thickness of the single-crystal GaN thick film can also be one of 5um to 400um, 5um to 300um, 10um to 500um, 20um to 500um, 50um to 500um, 50um to 400um, 100um to 500um, etc. For example, the thickness of the single-crystal GaN thick film can be one of 5um, 250um, 500um, etc.

[0141] Step 330: The seed crystal layer is peeled off from the sapphire substrate by stress self-separation or laser ablation technology to form a GaN single crystal substrate.

[0142] Stress-induced self-separation technology refers to the technique of peeling GaN and sapphire substrates using the thermal stress generated by the difference in their coefficients of thermal expansion. Laser ablation technology refers to the technique of achieving effective separation using a laser beam of a specific wavelength.

[0143] In some embodiments, the defect density of the GaN single-crystal substrate is less than or equal to 5E6cm. -2 For example, the defect density of a GaN single-crystal substrate is 2E6cm⁻¹. -2 3E6cm -2 5E6cm -2 One of them.

[0144] The GaN single-crystal substrate prepared by the method described in the embodiments of this specification has a low defect density, which can reduce dislocations and microtube defects in the epitaxial layer and provide better current conduction and photoelectric conversion efficiency.

[0145] Figure 4 This is an exemplary flowchart of another single crystal preparation method according to some embodiments of this specification. In some embodiments, process 400 may be performed manually. Figure 4As shown, process 400 includes the following steps.

[0146] Step 410: The single crystal substrate is introduced into the reaction chamber of MOCVD metal-organic chemical vapor deposition, and the single crystal growth of the lower cladding layer is performed using MOCVD metal-organic chemical vapor deposition.

[0147] In some embodiments, the single-crystal substrate may be a GaN single-crystal substrate prepared by process 300.

[0148] In some embodiments, the growth conditions of the lower cladding layer include: a growth temperature of 1000℃~1200℃, a growth pressure of 100Torr~300Torr, reactant elements of TMGa, TEGa, TMAl, TMIn, NH3, N2, and H2, a rotation speed of 1000 rpm~1300 rpm, a growth rate of 0.2µm / h~3µm / h, a V / III ratio of 100~80000, and a dopant element of either SiH4 or silane; the lower cladding layer is grown on a single crystal substrate by controlling the appropriate combination of temperature, pressure, reactant element selection and ratio, rotation speed, growth rate, V / III ratio, and dopant elements.

[0149] The V / III ratio refers to the molar flow ratio of Group V elements to Group III elements in the reaction gas or source material during semiconductor material growth (especially MOCVD technology). Group V elements include N, provided in gaseous form, such as NH3. Group III elements include Ga, Al, In, etc., provided in the form of metal-organic sources (e.g., TMGa, TMIn) or solid-state sources.

[0150] Dopant elements refer to trace amounts of foreign atoms artificially introduced into semiconductor materials to alter the electrical, optical, or structural properties of semiconductors, such as conductivity type, carrier concentration, mobility, and other key characteristics.

[0151] In some embodiments, the growth conditions of the lower coating layer may further include: a growth temperature of one of 1000℃~1100℃, 1100℃~1200℃, 1050℃~1150℃, a growth pressure of one of 100Torr~250Torr, 100Torr~200Torr, 150Torr~300Torr, 150Torr~250Torr, a rotation speed of one of 1000 rpm~1200 rpm, 1100 rpm~1300 rpm, 1100 rpm~1200 rpm, a growth rate of one of 0.2µm / h~2µm / h, 0.5µm / h~3µm / h, 0.5µm / h~2µm / h, 1µm / h~3µm / h, and a V / III ratio of one of 100~60000, 100~40000, 100~20000, 500~80000. For example, the growth temperature is one of 1000℃, 1100℃, 1200℃, etc.; the growth pressure is one of 100Torr, 200Torr, 300Torr, etc.; the rotation speed is one of 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, etc.; the growth rate is one of 0.2um / h, 1um / h, 2um / h, 3um / h, etc.; and the V / III ratio is one of 100, 40000, 80000, etc.

[0152] In the embodiments of this specification, by optimizing the growth conditions of the lower coating layer, the material quality and crystal integrity can be optimized, precise composition and doping control can be achieved, and the lower coating layer can be grown efficiently.

[0153] Step 420: Use MOCVD to grow a first light absorption loss suppression layer on the lower coating layer.

[0154] In some embodiments, the conditions for forming the first light absorption loss suppression layer include: a growth temperature of 1000℃~1150℃, a growth pressure of 100Torr~200Torr, reactant elements of TMGa, TEGa, TMAl, TMIn, NH3, N2, and H2, a rotation speed of 1000 rpm~1300 rpm, a growth rate of 0.5µm / h~5µm / h, a V / III ratio of 100~80000, and a dopant element of either SiH4 or silane; the first light absorption loss suppression layer is grown on a single crystal substrate by controlling the appropriate combination of temperature, pressure, reactant element selection and ratio, rotation speed, growth rate, V / III ratio, and dopant elements.

[0155] In some embodiments, the conditions for forming the first light absorption loss suppression layer may further include: a growth temperature of one of 1000℃~1100℃, 1050℃~1150℃, or 1050℃~1100℃; a growth pressure of one of 100Torr~150Torr, 150Torr~200Torr, or 125Torr~175Torr; a rotation speed of one of 1000 rpm~1200 rpm, 1100 rpm~1300 rpm, or 1100 rpm~1200 rpm; a growth rate of one of 0.5µm / h~4µm / h, 0.5µm / h~3µm / h, 1µm / h~5µm / h, or 2µm / h~5µm / h; and a V / III ratio of one of 100~60000, 100~40000, 100~20000, or 500~80000. For example, the growth temperature is one of 1000℃, 1100℃, 1150℃, etc.; the growth pressure is one of 100Torr, 150Torr, 200Torr, etc.; the rotation speed is one of 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, etc.; the growth rate is one of 0.5um / h, 2.5um / h, 5um / h, etc.; and the V / III ratio is one of 100, 40000, 80000, etc.

[0156] In some embodiments, the temperature change curve is controlled as y = A4 + B4 * p4. x The distribution of the radiative recombination coefficient of the first light absorption loss suppression layer conforms to the third radiation function y = C⁴ + D⁴*x -a4 The curve fraction, and make the light absorption coefficient of the first light absorption loss suppression layer conform to the fourth light absorption function y=E4+F4*d4 x The distribution of the curves is such that the third radiation function is distributed in the third quadrant, where p4 > 1, a4 > 1 and is odd, d4 ​​> 1, and A4, B4, C4, D4, E4, and F4 are constants. For example, p4 = 4, a4 ​​= 3, and d4 = 2.

[0157] Among them, the temperature change curve refers to the curve of the growth temperature change.

[0158] In some embodiments, if A4 = 0 and B4 = 1, the temperature change curve can be represented as y = p4. x .

[0159] In some embodiments, if C4 = 0 and D4 = 1, then the third radiation function can be expressed as y = x -a4 .

[0160] In some embodiments, if E4 = 0 and F4 = 1, then the fourth light absorption function can be expressed as y = d4. x .

[0161] In some embodiments, the curve controlling the Al / Ga element ratio is y = G4 + H4 * q4. x The hole mobility distribution of the first light absorption loss suppression layer conforms to the fourth mobility function y = J4 + K4*x -b4 The curve distribution is such that the density distribution of the first light absorption loss suppression layer conforms to the fourth density function y = L4 + M4*x. -c4 The curve distribution is such that the fourth mobility function and the fourth density function are distributed in the third quadrant, where q4 > 1, b4 > 1 and are odd, c4 > 1 and are odd, and G4, H4, J4, K4, L4, and M4 are constants. For example, q4 = 4, b4 = 3, and c4 = 2.

[0162] The Al / Ga element ratio curve refers to the relationship between the atomic ratio of Al and Ga and the changes in growth parameters (e.g., temperature, V / III ratio, etc.) or growth time / location.

[0163] In some embodiments, if G4 = 0 and H4 = 1, the element ratio change curve can be represented as y = q4. x .

[0164] In some embodiments, if J4 = 0 and K4 = 1, then the fourth mobility function can be expressed as y = x -b4 .

[0165] In some embodiments, if L4 = 0 and M4 = 1, then the fourth density function can be expressed as y = x -c4 .

[0166] In the embodiments of this specification, by controlling the growth conditions, radiative recombination coefficient, optical absorption coefficient, hole mobility distribution and density distribution of the first optical absorption loss suppression layer, the optical extraction efficiency, radiative recombination rate and carrier transport performance of the laser can be significantly improved.

[0167] Step 430: Use MOCVD to epitaxially grow a lower waveguide layer, an active layer, and an upper waveguide layer above the first optical absorption loss suppression layer.

[0168] In some embodiments, the growth conditions of the lower waveguide layer include: a growth temperature of 650℃ to 1000℃, a growth pressure of 100 Torr to 300 Torr, reactants of TMGa, TEGa, TMAl, TMIn, NH3, N2, and H2, a rotation speed of 400 rpm to 900 rpm, a growth rate of 0.05 μm / h to 2 μm / h, a V / III ratio of 1000 to 90000, and doping elements of any one of SiH4 or silane; the lower waveguide layer is grown above the substrate by controlling the appropriate combination of temperature, pressure, reactant selection and ratio, rotation speed, growth rate, V / III ratio, and doping elements.

[0169] In some embodiments, the growth conditions of the lower waveguide layer may further include: a growth temperature of one of 650℃~900℃, 650℃~800℃, 700℃~1000℃, or 700℃~900℃; a growth pressure of one of 100Torr~300Torr, 100Torr~200Torr, 200Torr~300Torr, or 150Torr~250Torr; and a rotation speed of 400 rpm~900 rpm. One of the following: 400-800 rpm, 400-600 rpm, 500-900 rpm; one of the following: growth rate: 0.05 μm / h-1.5 μm / h, 0.1 μm / h-2 μm / h, 0.2 μm / h-2 μm / h, 0.5 μm / h-2 μm / h; one of the following: V / III ratio: 1000-80000, 1000-60000, 2000-90000, 4000-90000. For example, the growth temperature is one of 650℃, 850℃, 1000℃, etc.; the growth pressure is one of 100Torr, 200Torr, 300Torr, etc.; the rotation speed is one of 400 rpm, 650 rpm, 900 rpm, etc.; the growth rate is one of 0.5um / h, 1um / h, 2um / h, etc.; and the V / III ratio is one of 1000, 40000, 90000, etc.

[0170] In some embodiments, the growth conditions of the active layer include: a growth temperature of 600℃ to 950℃, a growth pressure of 100 Torr to 250 Torr, reactant elements of TEGa, TMAl, TMIn, NH3, N2, and H2, a rotation speed of 300 rpm to 800 rpm, a growth rate of 0.002 μm / h to 2 μm / h, a V / III ratio of 1000 to 90000, and a dopant element of either SiH4 or silane; the active layer is grown on the substrate by controlling the appropriate combination of temperature, pressure, reactant element selection and ratio, rotation speed, growth rate, V / III ratio, and dopant elements.

[0171] In some embodiments, the growth conditions of the active layer may further include: a growth temperature of one of 650℃~900℃, 650℃~800℃, 700℃~950℃, or 700℃~900℃; a growth pressure of one of 100Torr~200Torr, 150Torr~250Torr, or 150Torr~200Torr; and a rotation speed of 300 rpm~700 rpm or 300 rpm~600 rpm. One of 400 rpm to 600 rpm, 400 rpm to 800 rpm, etc.; one of 0.002 μm / h to 1.5 μm / h, 0.002 μm / h to 1 μm / h, 0.02 μm / h to 2 μm / h, etc.; one of 0.2 μm / h to 2 μm / h, etc.; and one of 1000 to 80000, 1000 to 60000, 2000 to 90000, 4000 to 90000, etc. For example, the growth temperature is one of 600℃, 800℃, 950℃, etc.; the growth pressure is one of 100Torr, 150Torr, 250Torr, etc.; the rotation speed is one of 300 rpm, 500 rpm, 800 rpm, etc.; the growth rate is one of 0.002um / h, 1um / h, 2um / h, etc.; and the V / III ratio is one of 1000, 40000, 90000, etc.

[0172] In some embodiments, the growth conditions of the upper waveguide layer include: a growth temperature of 650℃ to 1000℃, a growth pressure of 100 Torr to 300 Torr, reactant elements of TMGa, TEGa, TMAl, TMIn, NH3, N2, and H2, a rotation speed of 400 rpm to 900 rpm, a growth rate of 0.05 μm / h to 2 μm / h, a V / III ratio of 1000 to 90000, and doping elements of either SiH4 or silane. The lower waveguide layer is grown above the substrate by controlling the appropriate combination of temperature, pressure, reactant element selection and ratio, rotation speed, growth rate, V / III ratio, and doping elements.

[0173] In some embodiments, the growth conditions of the upper waveguide layer may further include: a growth temperature of one of 650℃~900℃, 650℃~800℃, 700℃~1000℃, or 700℃~900℃; a growth pressure of one of 100Torr~300Torr, 100Torr~200Torr, 200Torr~300Torr, or 150Torr~250Torr; and a rotation speed of 400 rpm~900 rpm. One of the following: 400-800 rpm, 400-600 rpm, 500-900 rpm; one of the following: growth rate: 0.05 μm / h-1.5 μm / h, 0.1 μm / h-2 μm / h, 0.2 μm / h-2 μm / h, 0.5 μm / h-2 μm / h; one of the following: V / III ratio: 1000-80000, 1000-60000, 2000-90000, 4000-90000. For example, the growth temperature is one of 650℃, 800℃, 1000℃, etc.; the growth pressure is one of 100Torr, 200Torr, 300Torr, etc.; the rotation speed is one of 400 rpm, 650 rpm, 900 rpm, etc.; the growth rate is one of 0.05um / h, 1um / h, 2um / h, etc.; and the V / III ratio is one of 1000, 40000, 90000, etc.

[0174] In the embodiments described in this specification, by adjusting the growth conditions of the lower waveguide layer, the active layer, and the upper waveguide layer, the optical field confinement, carrier injection efficiency, radiative recombination rate, device reliability, and output performance of the laser can be affected, thereby obtaining a laser with better performance.

[0175] Step 440: A second optical absorption loss suppression layer is grown above the upper waveguide layer using MOCVD.

[0176] In some embodiments, the growth conditions of the second light absorption loss suppression layer include: a growth temperature of 800℃ to 1050℃, a growth pressure of 100 Torr to 200 Torr, reactant elements of TMGa, TEGa, TMAl, TMIn, NH3, N2, and H2, a rotation speed of 900 rpm to 1300 rpm, a growth rate of 0.5 μm / h to 5 μm / h, a V / III ratio of 200 to 80000, and a dopant element of any one of SiH4, silane, or Cp2Mg; the second light absorption loss suppression layer is grown on the substrate by controlling the appropriate combination of temperature, pressure, reactant element selection and ratio, rotation speed, growth rate, V / III ratio, and dopant elements.

[0177] In some embodiments, the conditions for forming the second light absorption loss suppression layer may further include: a growth temperature of one of 800℃~1000℃, 900℃~1050℃, or 800℃~950℃; a growth pressure of one of 100Torr~150Torr, 150Torr~200Torr, or 125Torr~175Torr; a rotation speed of one of 900 rpm~1200 rpm, 1000 rpm~1300 rpm, or 1000 rpm~1200 rpm; a growth rate of one of 0.5µm / h~4µm / h, 0.5µm / h~3µm / h, 1µm / h~5µm / h, or 2µm / h~5µm / h; and a V / III ratio of one of 200~60000, 200~40000, 200~20000, or 500~80000. For example, the growth temperature is one of 800℃, 950℃, 1050℃, etc.; the growth pressure is one of 100 Torr, 150 Torr, 200 Torr, etc.; the rotation speed is one of 900 rpm, 1100 rpm, 1200 rpm, 1300 rpm, etc.; the growth rate is one of 0.5 μm / h, 2.5 μm / h, 5 μm / h, etc.; and the V / III ratio is one of 200, 40000, 80000, etc.

[0178] In some embodiments, the temperature change curve is controlled as y = N4 + P4 * j4 x The curve distribution causes the radiative recombination coefficient distribution of the second light absorption loss suppression layer to have a curve distribution of the fourth radiation function y = Q⁴ + R⁴ * lnx, and causes the light absorption coefficient distribution of the second light absorption loss suppression layer to have a curve distribution of the fifth light absorption function y = S⁴ + T⁴ * g⁴. x The curve distribution is given by 0 < j4 < 1, 0 < g4 < 1, and N4, P4, Q4, R4, S4, and T4 are constants. For example, j4 = 0.5 and g4 = 0.5.

[0179] In some embodiments, if N4 = 0 and P4 = 1, the temperature change curve can be represented as y = j4. x .

[0180] In some embodiments, if Q4 = 0 and R4 = 1, then the fourth radiation function can be expressed as y = lnx.

[0181] In some embodiments, if S4 = 0 and T4 = 1, then the fifth light absorption function can be expressed as y = g4. x .

[0182] In some embodiments, the curve controlling the Al / Ga element ratio is y = U₄ + V₄ * k₄. xThe hole mobility distribution of the second optical absorption loss suppression layer is made to follow the curve distribution of the fifth mobility function y = W4 + Z4 * lnx, and the density distribution of the second optical absorption loss suppression layer is made to follow the curve distribution of the fifth density function y = O4 + I4 * lnx, where 0 < k4 < 1, and U4, V4, W4, Z4, O4, and I4 are constants. For example, k4 = 0.5.

[0183] In some embodiments, if U4 = 0 and V4 = 1, the element ratio change curve can be represented as y = k4. x .

[0184] In some embodiments, if W4 = 0 and Z4 = 1, then the fifth mobility function can be expressed as y = lnx.

[0185] In some embodiments, if O4 = 0 and I4 = 1, then the fifth density function can be expressed as y = lnx.

[0186] In the embodiments of this specification, by controlling the growth conditions, radiative recombination coefficient, optical absorption coefficient, hole mobility distribution and density distribution of the second optical absorption loss suppression layer, the optical extraction efficiency, radiative recombination rate and carrier transport performance of the laser can be significantly improved.

[0187] Step 450: An overlay layer is grown on top of the second optical absorption loss suppression layer using MOCVD epitaxy to prepare a nitride semiconductor laser with an optical absorption loss suppression layer.

[0188] The growth of the upper coating layer is similar to that of the lower coating layer, and the growth conditions are also similar.

[0189] It should be noted that the above descriptions of processes 300 and 400 are for illustrative purposes only and do not limit the scope of this specification. Those skilled in the art can make various modifications and changes to processes 300 and 400 under the guidance of this specification. However, such modifications and changes remain within the scope of this specification.

[0190] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this specification. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

[0191] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.

[0192] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this specification are not intended to limit the order of the processes and methods described herein. Although various examples have been discussed in the foregoing disclosure of some embodiments of the invention that are currently considered useful, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments; rather, the claims are intended to cover all modifications and equivalent combinations that conform to the spirit and scope of the embodiments described herein. For example, while the system components described above can be implemented using hardware devices, they can also be implemented solely using software solutions, such as installing the described system on existing servers or mobile devices.

[0193] Similarly, it should be noted that, in order to simplify the description disclosed herein and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of embodiments in this specification may sometimes combine multiple features into a single embodiment, drawing, or description thereof. However, this method of disclosure does not imply that the subject matter of this specification requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of a single embodiment disclosed above.

[0194] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this specification are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0195] For each patent, patent application, patent application publication, and other material, such as articles, books, specifications, publications, and documents, referenced in this specification, the entire contents of which are incorporated herein by reference. This excludes historical application documents that are inconsistent with or conflict with the content of this specification, as well as documents that limit the broadest scope of the claims in this specification (currently or subsequently appended to this specification). It should be noted that in the event of any inconsistency or conflict between the descriptions, definitions, and / or terminology used in the supplementary materials to this specification and the content of this specification, the descriptions, definitions, and / or terminology used in this specification shall prevail.

[0196] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and should be considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.

Claims

1. A nitride semiconductor laser, characterized in that, From bottom to top, it includes a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper cladding layer, wherein: A first optical absorption loss suppression layer is provided between the lower cladding layer and the lower waveguide layer, and a second optical absorption loss suppression layer is provided between the upper cladding layer and the upper waveguide layer. The first light absorption loss suppression layer and the second light absorption loss suppression layer constitute a light absorption loss suppression layer; The first light absorption loss suppression layer and the second light absorption loss suppression layer include any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, SiC, Ga2O3, BN and diamond.

2. The nitride semiconductor laser as described in claim 1, characterized in that, The radiative recombination coefficient of the first light absorption loss suppression layer is v1, and the radiative recombination coefficient of the second light absorption loss suppression layer is w1, where: 5*10 -13 (cm 3 / s)≤w1≤v1≤5*10 -9 (cm 3 / s); The radiative recombination coefficient distribution of the first light absorption loss suppression layer conforms to the first radiation function y=A1+B1*x -a1 The curve distribution of the second light absorption loss suppression layer is as follows: the first radiation function is a curve distribution in the third quadrant, and the radiation recombination coefficient distribution of the second radiation function y = C1 + D1 * lnx conforms to the curve distribution of the second radiation function, where a1 > 1 and is an odd number, A1, B1, C1 and D1 are constants, and x is a variable representing the thickness between the lower cladding layer and the lower waveguide layer or the thickness between the upper cladding layer and the upper waveguide layer. The hole mobility of the first light absorption loss suppression layer is t1, and the hole mobility of the second light absorption loss suppression layer is u1, where: 5 (cm 2 / V / s)≤u1≤t1≤5000(cm 2 / V / s); The hole mobility distribution of the first optical absorption loss suppression layer conforms to the first mobility function y=E1+F1*x -b1 The curve distribution of the second light absorption loss suppression layer is such that the first mobility function is the curve distribution of the third quadrant, and the hole mobility distribution of the second light absorption loss suppression layer conforms to the curve distribution of the second mobility function y = L1 + M1 * lnx, where b1 > 1 and is an odd number, and E1, F1, L1 and M1 are constants. The density of the first light absorption loss suppression layer is r, and the density of the second light absorption loss suppression layer is s, where: 1 (g / cm³) 3 )≤s≤r≤30(g / cm 3 The density distribution of the first light absorption loss suppression layer has a first density function y = G1 + H1*x. -c1 The density distribution of the second light absorption loss suppression layer has a curve distribution of the second density function y = J1 + K1 * lnx, where c1 > 1 and is an odd number, and G1, H1, J1 and K1 are constants. The radiative recombination coefficient distribution, hole mobility distribution, and density distribution of the first light absorption loss suppression layer have the following relationship: 0 < b1 < c1 < a1 < 100.

3. A nitride semiconductor laser as described in claim 1, characterized in that, The light absorption coefficient of the first light absorption loss suppression layer is m1, and the light absorption coefficient of the second light absorption loss suppression layer is n1, where 0.2*10 5 (cm -1 )≤m1≤n1≤3*10 5 (cm -1 ); The light absorption coefficient of the first light absorption loss suppression layer conforms to the first light absorption function y = N1 + P1 * d1 x The curve distribution of the light absorption coefficient of the second light absorption loss suppression layer conforms to the second light absorption function y = Q1 + R1 * g1 x The curve distribution is given by , where 0 < g1 < 1 < d1, and N1, P1, Q1, and R1 are constants.

4. A nitride semiconductor laser as described in claim 1, characterized in that, The upper waveguide layer is a strain-release upper waveguide layer; The strain-releasing upper waveguide layer includes any one or any combination of InGaN, GaN, InN, and AlInGaN. The covalent bond energy distribution of the strain-releasing upper waveguide layer conforms to an arc-shaped distribution. The covalent bond energy distribution of the strain-released upper waveguide layer conforms to the first covalent bond energy function y = A² + B² * log a2 The curve distribution of ((m2+x) / (m2-x)) is given, and the first covalent bond energy function is distributed in the second quadrant, where 0 < a2 < 1, m2 > 0, A2 and B2 are constants, and x is a variable. The density distribution of the strain-releasing waveguide layer conforms to an arc-shaped distribution; the density distribution of the strain-releasing waveguide layer conforms to the third density function y = C² + D² * log. b2 The curve distribution of ((n2+x) / (n2-x)) is given by the third density function, which is a curve distribution in the third quadrant, where b2>1, n2>0, and C2 and D2 are constants. The optical absorption coefficient distribution of the strain-release upper waveguide layer conforms to an arc-shaped distribution, and the optical absorption coefficient distribution of the strain-release upper waveguide layer conforms to the third optical absorption function y = E² + F² * log c2 The curve distribution of ((p2+x) / (p2-x)) is given, and the third light absorption function is a curve distribution in the second quadrant, where 0 < c2 < 1, p2 > 0, and E2 and F2 are constants. The hole mobility distribution of the strain-released upper waveguide layer conforms to an arc-shaped distribution, and the hole mobility distribution of the strain-released upper waveguide layer conforms to the third mobility function y = G² + H² * e x The curve distribution of / x, wherein the third mobility function is a curve distribution in the third quadrant, where G2 and H2 are constants; The covalent bond energy distribution, density distribution, and optical absorption coefficient distribution of the strain-released waveguide layer have the following relationship: 0 < a2 ≤ c2 < 1 < b2.

5. A nitride semiconductor laser as described in claim 1, characterized in that, The upper coating layer includes a first upper coating layer and a second upper coating layer, with an internal light absorption loss suppression layer between the first upper coating layer and the second upper coating layer; The internal light absorption loss suppression layer includes any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond. The angle at which the peak position of the valence band effective density of states in the internal optical absorption loss suppression layer decreases towards the quantum well is α; the angle at which the peak position of the valence band effective density of states in the internal optical absorption loss suppression layer decreases towards the surface is β; the angle at which the peak position of the valence band effective density of states in the first upper cladding layer decreases towards the quantum well is γ; and the angle at which the peak position of the valence band effective density of states in the second upper cladding layer decreases towards the surface is θ, wherein 30°≤α≤β≤γ≤θ≤90°; The angle at which the valley of the saturated electron drift velocity of the internal optical absorption loss suppression layer rises towards the quantum well is δ; the angle at which the valley of the saturated electron drift velocity of the internal optical absorption loss suppression layer rises towards the surface is σ; and the angle at which the valley of the saturated electron drift velocity of the first upper coating layer rises towards the quantum well is... The angle of ascent from the valley of the saturated electron drift velocity of the second upper coating layer towards the surface is ψ, where, The peak position of the deformation potential of the internal light absorption loss suppression layer decreases towards the quantum well at an angle of μ, the peak position of the deformation potential of the internal light absorption loss suppression layer decreases towards the surface at an angle of υ, the peak position of the deformation potential of the first upper coating layer decreases towards the quantum well at an angle of ρ, and the peak position of the deformation potential of the second upper coating layer decreases towards the surface at an angle of ω, wherein 10°≤μ≤υ≤ρ≤ω≤90°; The valley position of the bulk elastic modulus of the internal light absorption loss suppression layer rises at an angle ε towards the quantum well, the valley position of the bulk elastic modulus of the internal light absorption loss suppression layer rises at an angle η towards the surface, the valley position of the bulk elastic modulus of the first upper coating layer rises at an angle κ towards the quantum well, and the valley position of the bulk elastic modulus of the second upper coating layer rises at an angle ζ towards the surface, wherein 5°≤ε≤η≤κ≤ζ≤90°.

6. A nitride semiconductor laser as described in claim 5, characterized in that, 5°≤ε≤η≤μ≤υ≤δ≤σ≤α≤β≤90°.

7. A nitride semiconductor laser as described in claim 5, characterized in that, The valence band effective state density distribution of the internal light absorption loss suppression layer has a valence band effective state density function y = A³ + B³ * lnx - e x The curve distribution; The saturated electron drift velocity distribution of the internal light absorption loss suppression layer has an electron drift velocity function y = C³ + D³*x. 2 The curve distribution of +E3*sinx; The deformation potential distribution of the internal light absorption loss suppression layer has a deformation potential function y = F3 + H3 * lnx - J3 * e x The curve distribution; The bulk modulus distribution of the internal light absorption loss suppression layer has a curve distribution of the bulk modulus function y = K3 + L3*x + M3*1 / 2x, and the bulk modulus function is a curve distribution in the first quadrant. Among them, A3, B3, C3, D3, E3, F3, H3, J3, K3, L3 and M3 are constants.

8. A nitride semiconductor laser as described in claim 1, characterized in that, The active layer is a periodic structure composed of a well layer and a barrier layer, and the number of periods m satisfies 1 ≤ m ≤ 3. The well layer comprises any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond, and the thickness of the well layer is 10 angstroms to 100 angstroms. The barrier layer comprises any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond, and the thickness of the barrier layer is 10 angstroms to 150 angstroms. The lower cladding layer, lower waveguide layer, upper waveguide layer, and upper cladding layer include any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond. The substrate is a single-crystal substrate, including any one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, sapphire / SiNx, sapphire / SiO2 / SiNx composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2, and LiGaO2 composite substrate.

9. A single crystal preparation method for preparing a nitride semiconductor laser as described in claim 1, characterized in that, The substrate is a single-crystal substrate, and the single-crystal substrate is prepared by a multi-step growth method, including: A seed layer is epitaxially grown on a sapphire substrate in a metal-organic chemical vapor deposition (MOCVD) reaction chamber. The seed layer comprises multiple GaN layers, including a GaN buffer layer, a three-dimensional GaN growth layer, and a two-dimensional GaN growth layer. The growth conditions for the GaN buffer layer include: a temperature of 500℃–900℃, a pressure of 100 Torr–500 Torr, and a rotation speed of 600 rpm–12000 rpm. The thickness of the GaN buffer layer is 10 nm–200 nm. The growth conditions for the three-dimensional GaN growth layer include: a temperature of 900℃~1100℃, a pressure of 150Torr~500Torr, and a rotation speed of 600 rpm~12000 rpm, with a thickness of 200nm~5000nm; the growth conditions for the two-dimensional GaN growth layer include: a temperature of 1000℃~1200℃, a pressure of 150Torr~250Torr, and a rotation speed of 600 rpm~12000 rpm, with a thickness of 2000nm~10000nm. The seed crystal layer is placed in a hydride vapor phase epitaxy (HVPE) or chemical vapor deposition (CVD) reaction chamber to grow a single-crystal GaN thick film. The growth temperature of the single-crystal GaN thick film is 1000℃~1200℃, HCl is introduced, GaCl3 is used as the gallium source, and NH3 is used as the nitrogen source. The thickness of the single-crystal GaN thick film is 5um~500um. The seed layer is removed from the sapphire substrate using stress self-separation or laser ablation techniques to form a GaN single-crystal substrate; the defect density of the GaN single-crystal substrate is less than or equal to 5E6cm⁻¹. -2 .

10. A single crystal preparation method for preparing a nitride semiconductor laser as described in claim 1, characterized in that, The substrate is a single-crystal substrate, and the method includes: The single-crystal substrate is introduced into the reaction chamber of MOCVD (Metal-Organic Chemical Vapor Deposition) for single-crystal growth of the lower cladding layer. The growth conditions of the lower cladding layer include: a growth temperature of 1000℃~1200℃, a growth pressure of 100Torr~300Torr, reactant elements of TMGa, TEGa, TMAl, TMIn, NH3, N2, and H2, a rotation speed of 1000 rpm~1300 rpm, a growth rate of 0.2µm / h~3µm / h, a V / III ratio of 100~80000, and a dopant element of either SiH4 or silane. The lower cladding layer is grown on the substrate by controlling the appropriate combination of temperature, pressure, reactant element selection and ratio, rotation speed, growth rate, V / III ratio, and dopant elements. A first light absorption loss suppression layer is grown using MOCVD on the lower cladding layer. The formation conditions for the first light absorption loss suppression layer include: a growth temperature of 1000℃~1150℃, a growth pressure of 100Torr~200Torr, reactants of TMGa, TEGa, TMAl, TMIn, NH3, N2, and H2, a rotation speed of 1000 rpm~1300 rpm, a growth rate of 0.5µm / h~5µm / h, a V / III ratio of 100~80000, and a dopant element of either SiH4 or silane. The first light absorption loss suppression layer is grown on the substrate by controlling the appropriate combination of temperature, pressure, reactant selection and ratio, rotation speed, growth rate, V / III ratio, and dopant element. The temperature change curve is controlled as y=A4+B4*p4. x The radiative recombination coefficient distribution of the first light absorption loss suppression layer conforms to the third radiation function y = C⁴ + D⁴*x -a4 The curve distribution is such that the light absorption coefficient of the first light absorption loss suppression layer conforms to the fourth light absorption function y = E4 + F4 * d4. x The curve distribution of the third radiation function is a third quadrant curve distribution, wherein p4 > 1, a4 > 1 and is odd, d4 ​​> 1, and A4, B4, C4, D4, E4, and F4 are constants; the curve controlling the Al / Ga element ratio is y = G4 + H4 * q4. x The hole mobility distribution of the first light absorption loss suppression layer conforms to the fourth mobility function y = J4 + K4*x -b4 The curve distribution is such that the density distribution of the first light absorption loss suppression layer conforms to the fourth density function y = L4 + M4*x. -c4 The curve distribution is such that the fourth mobility function and the fourth density function are curve distributions in the third quadrant, where q4 > 1, b4 > 1 and are odd, c4 > 1 and are odd, and G4, H4, J4, K4, L4, and M4 are constants. The lower waveguide layer, the active layer, and the upper waveguide layer are epitaxially grown on top of the first optical absorption loss suppression layer using MOCVD. The growth conditions for the lower waveguide layer include: a growth temperature of 650℃~1000℃, a growth pressure of 100Torr~300Torr, reactant elements of TMGa, TEGa, TMAl, TMIn, NH3, N2, and H2, a rotation speed of 400 rpm~900 rpm, a growth rate of 0.05 μm / h~2 μm / h, and a V / III ratio of... The dopant concentration is 1000–90000, and the dopant element is any one of SiH4 or silane. The lower waveguide layer is grown above the substrate by controlling the temperature, pressure, selection and ratio of reacting elements, rotation speed, growth rate, V / III ratio, and a suitable combination of dopant elements. The growth conditions for the active layer include: a growth temperature of 600℃–950℃, a growth pressure of 100 Torr–250 Torr, and reacting elements of TEGa, TMAl, TMIn, NH3, N2, and H2. The growth rate is 0.002 μm / h to 2 μm / h, the V / III ratio is 1000 to 90000, and the doping element is either SiH4 or silane. The active layer is grown on the substrate by controlling the temperature, pressure, selection and ratio of reactants, rotation speed, growth rate, V / III ratio, and a suitable combination of doping elements. The growth conditions for the upper waveguide layer include: a growth temperature of 650℃ to 1000℃ and a growth pressure of 100 Torr. The upper waveguide layer is grown on a substrate at a rotation speed of 300 Torr, with reactants being TMGa, TEGa, TMAl, TMIn, NH3, N2, and H2, a rotation speed of 400 to 900 rpm, a growth rate of 0.05 μm / h to 2 μm / h, a V / III ratio of 1000 to 90000, and doping elements being either SiH4 or silane. The upper waveguide layer is grown on a substrate by controlling the temperature, pressure, selection and ratio of reactants, rotation speed, growth rate, V / III ratio, and appropriate combination of doping elements. A second optical absorption loss suppression layer is grown on top of the upper waveguide layer using MOCVD. The growth conditions for the second optical absorption loss suppression layer include: a growth temperature of 800℃~1050℃, a growth pressure of 100Torr~200Torr, reactants of TMGa, TEGa, TMAl, TMIn, NH3, N2, and H2, a rotation speed of 900 rpm~1300 rpm, a growth rate of 0.5µm / h~5µm / h, a V / III ratio of 200~80000, and doping elements of any one of SiH4, silane, or Cp2Mg. The second optical absorption loss suppression layer is grown on the substrate by controlling the appropriate combination of temperature, pressure, reactant selection and ratio, rotation speed, growth rate, V / III ratio, and doping elements. The temperature change curve is controlled as y=N4+P4*j4. x The curve distribution causes the radiative recombination coefficient distribution of the second light absorption loss suppression layer to have a curve distribution of the fourth radiation function y = Q⁴ + R⁴ * lnx, and causes the light absorption coefficient distribution of the second light absorption loss suppression layer to have a curve distribution of the fifth light absorption function y = S⁴ + T⁴ * g⁴. x The curve distribution is given by y = U4 + V4 * k4, where 0 < j4 < 1, 0 < g4 < 1, and N4, P4, Q4, R4, S4, and T4 are constants; the curve controlling the Al / Ga element ratio is given by y = U4 + V4 * k4. x The hole mobility distribution of the second light absorption loss suppression layer is made to have a curve distribution of the fifth mobility function y = W4 + Z4 * lnx, and the density distribution of the second light absorption loss suppression layer is made to have a curve distribution of the fifth density function y = O4 + I4 * lnx, where 0 < k4 < 1, and U4, V4, W4, Z4, O4 and I4 are constants. A nitride semiconductor laser with an optical absorption loss suppression layer is fabricated by using MOCVD epitaxial growth on top of the second optical absorption loss suppression layer.

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