Epitaxial structure of nitride semiconductor laser with kink suppression layer

Abstract

The invention provides an epitaxial structure of a nitride semiconductor laser with a kink suppression layer, which comprises a substrate, a lower limiting layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, an upper limiting layer and a contact layer which are sequentially arranged from bottom to top, and is characterized in that a first kink suppression layer is arranged between the lower limiting layer and the substrate; and a second kink suppression layer is arranged between the upper limiting layer and the contact layer. The kink suppression layer is arranged in the epitaxial structure of the nitride semiconductor laser, and the change angles of the Al element concentration, the In element concentration, the H element concentration, the C element concentration and the O element concentration in the kink suppression layer are set, so that the uniformity of the structure and the interface uniformity of the Al element concentration, the H element concentration, the C element concentration and the O element concentration are improved; the disturbance of minority carriers is reduced, the probability that stimulated radiation has a high-order transverse mode is reduced, the problem of gain reduction of a fundamental mode is inhibited, the kink of a PI curve is improved, and the divergence angle of a slow axis is reduced.

Description

Technical Field

[0001] The present application relates to the field of semiconductor optoelectronic devices, and in particular to an epitaxial structure of a nitride semiconductor laser with a kink suppression layer. Background Art

[0002] Lasers are widely used in laser display, laser TV, laser projector, communication, medical treatment, weapons, guidance, ranging, spectral analysis, cutting, precision welding, high-density optical storage and other fields. There are many types of lasers, and the classification methods are also diverse, mainly including solid, gas, liquid, semiconductor and dye types of lasers; compared with other types of lasers, all-solid-state semiconductor lasers have the advantages of small size, high efficiency, light weight, good stability, long life, simple and compact structure, and miniaturization.

[0003] There are big differences between lasers and nitride semiconductor light-emitting diodes:

[0004] 1) Laser is generated by stimulated radiation of carriers, the spectrum half-width is small, the brightness is very high, and the output power of a single laser can be in the W level, while nitride semiconductor light-emitting diodes are spontaneously radiated, and the output power of a single light-emitting diode is in the mW level;

[0005] 2) The current density of the laser reaches KA / cm2, which is more than 2 orders of magnitude higher than that of nitride light-emitting diodes, resulting in stronger electron leakage, more serious Auger recombination, stronger polarization effect, more serious electron-hole mismatch, and more serious efficiency attenuation Droop effect;

[0006] 3) The spontaneous transition radiation of the light-emitting diode is incoherent light that transitions from a high energy level to a low energy level without any external influence, while the laser is stimulated transition radiation, and the energy of the induced photon should be equal to the difference in the energy level of the electron transition, producing the same coherent light as the photon and the induced photon;

[0007] 4) Different principles: When an external voltage is applied to a light-emitting diode, electron holes jump to a quantum well or a pn junction to generate radiative recombination light, while a laser can only emit when the lasing conditions are met. The carrier distribution in the active region must be reversed, and the stimulated radiation light oscillates back and forth in the resonant cavity. The propagation in the gain medium amplifies the light, and the threshold condition is met so that the gain is greater than the loss, and finally the laser is output.

[0008] Nitride semiconductor lasers have the following problems: Kink kink means that high-order transverse (side) modes begin to appear or the polarization state changes in the propagation direction, and the radiation mode jumps from the base side mode to the higher-order mode or changes from the TE mode to the TM mode. Material inhomogeneity or structural inhomogeneity causes minority carrier disturbances in the active region. The lateral distribution shape concentrated on the base side mode reduces the carrier concentration in the center of the active region, causing the local gain distribution to flatten, weakening the junction plane waveguide effect and changing the mode distribution, enhancing the penetration and diffusion of carriers into the passive region, and ultimately leading to increased radiation loss, reduced base mode gain, and kinks in the emission characteristics. At the same time, the optical mode moves relative to the center along the junction plane, and the radiation self-focusing effect also causes the PI curve to kink. As the current increases, the imaginary and real parts of the refractive index change, causing the shape of the radiation mode spectrum to be distorted, the external differential quantum efficiency of the base side mode decreases, and the emission characteristics begin to bend, causing the kink critical current to decrease. Summary of the invention

[0009] To solve one of the above technical problems, the present invention provides an epitaxial structure of a nitride semiconductor laser having a kink suppression layer.

[0010] An embodiment of the present invention provides an epitaxial structure of a nitride semiconductor laser with a kink suppression layer, comprising a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, an upper confinement layer and a contact layer arranged in sequence from bottom to top, a first kink suppression layer is arranged between the lower confinement layer and the substrate, a second kink suppression layer is arranged between the upper confinement layer and the contact layer, a peak position of an Al element concentration of the first kink suppression layer has a decreasing angle of 15° to 60° toward the substrate, a peak position of an H element concentration of the first kink suppression layer has a decreasing angle of 30° to 90° toward the substrate, a peak position of an C element concentration of the first kink suppression layer has a decreasing angle of 0° to 45° toward the substrate, and a peak position of an H element concentration of the first kink suppression layer has a decreasing angle of 0° to 45° toward the substrate. The O element concentration peak position of the first kink suppression layer has a descending angle of 0° to 45° toward the substrate, the Al element concentration peak position of the second kink suppression layer has a descending angle of 45° to 90° toward the contact layer, the In element concentration valley position of the second kink suppression layer has a rising angle of 45° to 90° toward the contact layer, the H element concentration valley position of the second kink suppression layer has a rising angle of 30° to 90° toward the contact layer, the C element concentration valley position of the second kink suppression layer has a rising angle of 0° to 45° toward the contact layer, and the O element concentration valley position of the second kink suppression layer has a rising angle of 30° to 90° toward the contact layer, and the angles are tangent inclination angles along the curve.

[0011] Preferably, the descending angle of the Al element concentration peak position of the first kink suppression layer toward the substrate is ≤ the descending angle of the Al element concentration peak position of the second kink suppression layer toward the contact layer is ≤ the rising angle of the In element concentration valley position of the second kink suppression layer toward the contact layer.

[0012] Preferably, the descending angle of the peak position of the C element concentration of the first kink suppression layer toward the substrate is ≤ the descending angle of the peak position of the O element concentration of the first kink suppression layer toward the substrate is ≤ the descending angle of the peak position of the Al element concentration of the first kink suppression layer toward the substrate is ≤ the descending angle of the peak position of the H element concentration of the first kink suppression layer toward the substrate;

[0013] The rising angle of the valley value position of the C element concentration of the second kink suppression layer toward the contact layer is ≤ the rising angle of the valley value position of the H element concentration of the second kink suppression layer toward the contact layer is ≤ the rising angle of the valley value position of the O element concentration of the second kink suppression layer toward the contact layer is ≤ the falling angle of the peak position of the Al element concentration of the second kink suppression layer toward the contact layer is ≤ the rising angle of the valley value position of the In element concentration of the second kink suppression layer toward the contact layer.

[0014] Preferably, the first kink suppression layer, the second kink suppression layer, the upper confinement layer and the lower confinement layer all have electron effective mass characteristics, the decrease angle α of the peak position of the electron effective mass of the first kink suppression layer toward the substrate is: 15°≤α≤60°, the decrease angle β of the peak position of the electron effective mass of the second kink suppression layer toward the contact layer is: 45°≤β≤90°, the decrease angle γ of the peak position of the electron effective mass of the upper confinement layer toward the active layer is: 0°≤γ≤30°, the decrease angle θ of the peak position of the electron effective mass of the lower confinement layer toward the substrate is: 0°≤θ≤30°, and θ≤γ≤α≤β.

[0015] Preferably, the first kink suppression layer, the second kink suppression layer, the upper confinement layer and the lower confinement layer all have bandgap width characteristics, the descending angle ω of the peak position of the bandgap width of the first kink suppression layer toward the substrate direction is: 15°≤ω≤60°, the descending angle δ of the peak position of the bandgap width of the second kink suppression layer toward the contact layer direction is: 45°≤δ≤90°, the descending angle ψ of the peak position of the bandgap width of the upper confinement layer toward the active layer direction is: 0°≤ψ≤30°, the descending angle ε of the peak position of the bandgap width of the lower confinement layer toward the substrate direction is: 0°≤ε≤30°, and ε≤ψ≤ω≤δ.

[0016] Preferably, the first kink suppression layer, the second kink suppression layer, the upper confinement layer and the lower confinement layer all have peak rate electric field characteristics, the decreasing angle μ of the peak position of the peak rate electric field of the first kink suppression layer toward the substrate is: 15°≤μ≤60°, the decreasing angle ρ of the peak position of the peak rate electric field of the second kink suppression layer toward the contact layer is: 45°≤ρ≤90°, the decreasing angle υ of the peak position of the peak rate electric field of the upper confinement layer toward the active layer is: 0°≤υ≤30°, the decreasing angle χ of the peak position of the peak rate electric field of the lower confinement layer toward the substrate is: 0°≤χ≤30°, and χ≤υ≤μ≤ρ.

[0017] Preferably, the first kink suppression layer, the second kink suppression layer, the upper confinement layer and the lower confinement layer all have separation energy characteristics, the decrease angle κ of the peak position of the separation energy of the first kink suppression layer toward the substrate direction is: 15°≤κ≤60°, the decrease angle ζ of the peak position of the separation energy of the second kink suppression layer toward the contact layer direction is: 45°≤ζ≤90°, the decrease angle τ of the peak position of the separation energy of the upper confinement layer toward the active layer direction is: 0°≤τ≤30°, the decrease angle π of the peak position of the separation energy of the lower confinement layer toward the substrate direction is: 0°≤π≤30°, and π≤τ≤ζ≤κ.

[0018] Preferably, the relationship among the decreasing angle α of the peak position of the electron effective mass of the first kink suppression layer toward the substrate, the decreasing angle ω of the peak position of the bandgap width of the first kink suppression layer toward the substrate, the decreasing angle μ of the peak position of the peak rate electric field of the first kink suppression layer toward the substrate, and the decreasing angle κ of the peak position of the separation energy of the first kink suppression layer toward the substrate is: 15°≤κ≤α≤ω≤μ≤60°;

[0019] The relationship between the decreasing angle β of the peak position of the electron effective mass of the second kink suppression layer toward the contact layer, the decreasing angle δ of the peak position of the bandgap width of the second kink suppression layer toward the contact layer, the decreasing angle ρ of the peak position of the peak rate electric field of the second kink suppression layer toward the contact layer, and the decreasing angle ζ of the peak position of the separation energy of the second kink suppression layer toward the contact layer is: 45°≤ζ≤β≤δ≤ρ≤90°.

[0020] Preferably, the electron effective mass of the first kink suppression layer has the function y1=A+B*sinx1 / x1 2 The curve distribution in the third quadrant, the electron effective mass of the second kink suppression layer has the function y2=C+D*lnx2+x2 curve distribution, and the band gap width of the first kink suppression layer has the function y3=E+F*sinx1 / x1 2The third quadrant curve distribution, the bandgap width of the second kink suppression layer has a function y4 = G + H * lnx2 + x2 curve distribution, the peak rate electric field of the first kink suppression layer has a function y5 = J + K * sinx1 / x1 2 The third quadrant curve distribution, the peak rate electric field of the second kink suppression layer has a function y6 = L + M * lnx2 + x2 curve distribution, the separation energy of the first kink suppression layer has a function y7 = N + P * sinx1 / x1 2 The third quadrant curve distribution, the separation energy of the second kink suppression layer has a function y8=Q+R*lnx2+x2 curve distribution, wherein x1 is the depth of the first kink suppression layer toward the lower limiting layer, x2 is the depth of the second kink suppression layer toward the contact layer, A≤E≤N≤J, C≤G≤Q≤L, and A≤C≤E≤G≤N≤Q≤J≤L.

[0021] Preferably, the first kink suppression layer and the second kink suppression layer are any one or any combination of InGaN, InN, AlInGaN, GaN, AlGaN, InGaN / GaN superlattice, InGaN / AlInN superlattice, InGaN / AlGaN superlattice, InGaN / AlInGaN superlattice, GaN / AlInN superlattice, GaN / AlGaN superlattice, InGaN / InGaN superlattice, AlInGaN / AlInGaN superlattice or any combination with GaN.

[0022] Preferably, the active layer is a periodic structure composed of a well layer and a barrier layer, the number of periods is 3≥m≥1, and the well layer is any one or any 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, diamond combination, with a thickness of 10 angstroms to 150 angstroms; the barrier layer is 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, with a thickness of 10 angstroms to 200 angstroms.

[0023] Preferably, the lower limiting layer, the lower waveguide layer, the upper waveguide layer, the electron blocking layer and the upper limiting layer are 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.

[0024] Preferably, the substrate is a single crystal substrate, such as sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, sapphire / SiN x , Sapphire / SiO2 / SiN x Composite substrate, sapphire / SiN x Any one of a / SiO2 composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0025] The beneficial effects of the present invention are as follows: the present invention sets a kink suppression layer in the epitaxial structure of a nitride semiconductor laser, and sets the variation angles of the Al element concentration, the In element concentration, the H element concentration, the C element concentration and the O element concentration in the kink suppression layer, thereby improving the uniformity of the structure and the interface uniformity of the Al element concentration, the H element concentration, the C element concentration and the O element concentration, reducing the disturbance of minority carriers, reducing the probability of the occurrence of high-order transverse modes in stimulated radiation, suppressing the gain reduction problem of the fundamental mode, improving the kink of the PI curve and reducing the slow axis divergence angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0027] Figure 1 A schematic structural diagram of an epitaxial structure of a nitride semiconductor laser with a kink suppression layer according to an embodiment of the present invention;

[0028] Figure 2 A SIMS secondary ion mass spectrum of an epitaxial structure of a nitride semiconductor laser with a kink suppression layer according to an embodiment of the present invention;

[0029] Figure 3 A locally enlarged SIMS secondary ion mass spectrum of the first kink suppression layer of the epitaxial structure of the nitride semiconductor laser with a kink suppression layer according to an embodiment of the present invention;

[0030] Figure 4 A SIMS secondary ion mass spectrum of a second kink suppression layer of a partially enlarged portion of the epitaxial structure of a nitride semiconductor laser with a kink suppression layer according to an embodiment of the present invention.

[0031] Reference numerals:

[0032] 100. Substrate, 101. Lower confinement layer, 102. Lower waveguide layer, 103. Active layer, 104. Upper waveguide layer, 105. Electron blocking layer, 106. Upper confinement layer, 107. Contact layer, 108. Kink suppression layer; 108a. First kink suppression layer, 108b. Second kink suppression layer. DETAILED DESCRIPTION

[0033] In order to make the technical solutions and advantages in the embodiments of the present application more clearly understood, the exemplary embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0034] like Figures 1 to 4 As shown, this embodiment provides an epitaxial structure of a nitride semiconductor laser with a kink suppression layer, comprising a substrate 100, a lower confinement layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, an electron blocking layer 105, an upper confinement layer 106 and a contact layer 107 arranged in sequence from bottom to top. A kink suppression layer 108 is also arranged in the epitaxial structure of the nitride semiconductor laser with a kink suppression layer.

[0035] Specifically, in this embodiment, the epitaxial structure of the nitride semiconductor laser with a kink suppression layer is provided with a substrate 100, a lower confinement layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, an electron blocking layer 105, an upper confinement layer 106 and a contact layer 107 in order from bottom to top. A first kink suppression layer 108a is provided between the lower confinement layer 101 and the substrate 100. A second kink suppression layer 108b is provided between the upper confinement layer 106 and the contact layer 107. The first kink suppression layer 108a and the second kink suppression layer 108b constitute a kink suppression layer 108.

[0036] In this embodiment, the first kink suppression layer 108a has Al element concentration characteristics, H element concentration characteristics, C element concentration characteristics and O element concentration characteristics, and the Al element concentration, H element concentration, C element concentration and O element concentration in the first kink suppression layer 108a also have a certain change trend toward the substrate 100, which is specifically manifested as follows:

[0037] The peak position of the Al element concentration of the first kink suppression layer 108a shows a gradual downward trend toward the substrate 100;

[0038] The peak position of the H element concentration of the first kink suppression layer 108a shows a sudden downward trend toward the substrate 100;

[0039] The peak position of the C element concentration of the first kink suppression layer 108a shows a gradual downward trend toward the substrate 100;

[0040] The peak position of the O element concentration of the first kink suppression layer 108a shows a gradual downward trend toward the substrate 100;

[0041] where angle is the inclination angle of the tangent line along the curve.

[0042] Furthermore, the decreasing angle of the peak position of the Al element concentration of the first kink suppression layer 108a toward the substrate 100 is 15° to 60°, the decreasing angle of the peak position of the H element concentration of the first kink suppression layer 108a toward the substrate 100 is 30° to 90°, the decreasing angle of the peak position of the C element concentration of the first kink suppression layer 108a toward the substrate 100 is 0° to 45°, and the decreasing angle of the peak position of the O element concentration of the first kink suppression layer 108a toward the substrate 100 is 0° to 45°.

[0043] In addition, in this embodiment, the second kink suppression layer 108 b has Al element concentration characteristics, In element concentration characteristics, H element concentration characteristics, C element concentration characteristics, and O element concentration characteristics, and the Al element concentration, In element concentration, H element concentration, C element concentration, and O element concentration in the second kink suppression layer 108 b also have a certain change trend toward the contact layer 107, which is specifically manifested as follows:

[0044] The peak position of the Al element concentration in the second kink suppression layer 108b shows a sudden downward trend toward the contact layer 107;

[0045] The In element concentration valley position of the second kink suppression layer 108b shows a sudden upward trend toward the contact layer 107;

[0046] The H element concentration valley position of the second kink suppression layer 108b shows a sudden upward trend toward the contact layer 107;

[0047] The C element concentration valley position of the second kink suppression layer 108b shows a sudden upward trend toward the contact layer 107;

[0048] The O element concentration valley position of the second kink suppression layer 108 b shows a gradually increasing trend toward the contact layer 107 .

[0049] Furthermore, the descending angle of the peak position of the Al element concentration of the second kink suppression layer 108b toward the contact layer 107 is 45° to 90°, the rising angle of the valley position of the In element concentration of the second kink suppression layer 108b toward the contact layer 107 is 45° to 90°, the rising angle of the valley position of the H element concentration of the second kink suppression layer 108b toward the contact layer 107 is 30° to 90°, the rising angle of the valley position of the C element concentration of the second kink suppression layer 108b toward the contact layer 107 is 0° to 45°, and the rising angle of the valley position of the O element concentration of the second kink suppression layer 108b toward the contact layer 107 is 30° to 90°.

[0050] In this embodiment, a kink suppression layer 108 is provided in the epitaxial structure of the nitride semiconductor laser, and the variation angles of the Al element concentration, the In element concentration, the H element concentration, the C element concentration and the O element concentration in the kink suppression layer 108 are set to improve the uniformity of the structure and the interface uniformity of the Al element concentration, the H element concentration, the C element concentration and the O element concentration, reduce the disturbance of minority carriers, reduce the probability of the occurrence of high-order transverse modes by stimulated radiation, suppress the gain reduction problem of the fundamental mode, improve the kink of the PI curve and reduce the slow axis divergence angle.

[0051] In some optional embodiments, the descending angle of the peak position of the Al element concentration of the first kink suppression layer 108a toward the substrate 100, the descending angle of the peak position of the Al element concentration of the second kink suppression layer 108b toward the contact layer 107, and the rising angle of the valley position of the In element concentration of the second kink suppression layer 108b toward the contact layer 107 have the following relationship:

[0052] The descending angle of the peak Al concentration position of the first kink suppression layer 108a toward the substrate 100 is ≤ the descending angle of the peak Al concentration position of the second kink suppression layer 108b toward the contact layer 107 is ≤ the rising angle of the valley In concentration position of the second kink suppression layer 108b toward the contact layer 107.

[0053] This embodiment designs the relationship between the descending angle of the Al element concentration peak position of the first kink suppression layer 108a toward the substrate 100, the descending angle of the Al element concentration peak position of the second kink suppression layer 108b toward the contact layer 107, and the rising angle of the In element concentration valley position of the second kink suppression layer 108b toward the contact layer 107. It is possible to regulate the movement position of the optical mode along the junction plane relative to the active layer 103, improve the uniformity of the carrier concentration in the center of the active layer 103, reduce the distortion of the radiation mode spectrum shape, improve the radiation self-focusing effect, regulate the lateral distribution shape of the base side mode of the laser, improve the linearity of the external differential quantum efficiency of the base side mode, suppress the bending of the emission characteristics, and improve the kink critical current and thermal reversal current density.

[0054] In some optional embodiments, the descending angle of the peak position of the C element concentration of the first kink suppression layer 108a toward the substrate 100, the descending angle of the peak position of the O element concentration of the first kink suppression layer 108a toward the substrate 100, the descending angle of the peak position of the Al element concentration of the first kink suppression layer 108a toward the substrate 100, and the descending angle of the peak position of the H element concentration of the first kink suppression layer 108a toward the substrate 100 have the following relationship:

[0055] The descending angle of the peak position of the C element concentration of the first kink suppression layer 108a toward the substrate 100 is ≤ the descending angle of the peak position of the O element concentration of the first kink suppression layer 108a toward the substrate 100 is ≤

[0056] The descending angle of the peak position of the Al element concentration of the first kink suppression layer 108 a toward the substrate 100 is ≤ the descending angle of the peak position of the H element concentration of the first kink suppression layer 108 a toward the substrate 100 .

[0057] In some optional embodiments, the rising angle of the C element concentration valley position of the second kink suppression layer 108b toward the contact layer 107, the rising angle of the H element concentration valley position of the second kink suppression layer 108b toward the contact layer 107, the rising angle of the O element concentration valley position of the second kink suppression layer 108b toward the contact layer 107, the falling angle of the Al element concentration peak position of the second kink suppression layer 108b toward the contact layer 107, and the rising angle of the In element concentration valley position of the second kink suppression layer 108b toward the contact layer 107 have the following relationship:

[0058] The rising angle of the valley value position of the C element concentration of the second kink suppression layer 108b toward the contact layer 107 is ≤ the rising angle of the valley value position of the H element concentration of the second kink suppression layer 108b toward the contact layer 107 is ≤ the rising angle of the valley value position of the O element concentration of the second kink suppression layer 108b toward the contact layer 107 is ≤ the falling angle of the peak position of the Al element concentration of the second kink suppression layer 108b toward the contact layer 107 is ≤ the rising angle of the valley value position of the In element concentration of the second kink suppression layer 108b toward the contact layer 107.

[0059] In some optional embodiments, the first kink suppression layer 108a, the second kink suppression layer 108b, the upper confinement layer 106 and the lower confinement layer 101 all have electron effective mass characteristics, and the electron effective mass in the first kink suppression layer 108a, the second kink suppression layer 108b, the upper confinement layer 106 and the lower confinement layer 101 also has a certain variation trend, which is specifically manifested as follows:

[0060] The peak position of the electron effective mass of the first kink suppression layer 108a shows a gradual downward trend toward the substrate 100;

[0061] The peak position of the electron effective mass of the second kink suppression layer 108b shows a sudden downward trend toward the contact layer 107;

[0062] The peak position of the electron effective mass of the upper confinement layer 106 shows a slowly decreasing trend toward the active layer 103;

[0063] The peak position of the electron effective mass of the lower confinement layer 101 shows a gradually decreasing trend toward the substrate 100 .

[0064] Furthermore, the decreasing angle α of the peak position of the electron effective mass of the first kink suppression layer 108a toward the substrate 100 is: 15°≤α≤60°, the decreasing angle β of the peak position of the electron effective mass of the second kink suppression layer 108b toward the contact layer 107 is: 45°≤β≤90°, the decreasing angle γ of the peak position of the electron effective mass of the upper confinement layer 106 toward the active layer 103 is: 0°≤γ≤30°, the decreasing angle θ of the peak position of the electron effective mass of the lower confinement layer 101 toward the substrate 100 is: 0°≤θ≤30°, and θ≤γ≤α≤β.

[0065] In some optional embodiments, the first kink suppression layer 108a, the second kink suppression layer 108b, the upper confinement layer 106 and the lower confinement layer 101 all have a bandgap width characteristic, and the bandgap widths in the first kink suppression layer 108a, the second kink suppression layer 108b, the upper confinement layer 106 and the lower confinement layer 101 also have a certain variation trend, which is specifically manifested as follows:

[0066] The peak position of the bandgap width of the first kink suppression layer 108a shows a gradual downward trend toward the substrate 100;

[0067] The peak position of the bandgap width of the second kink suppression layer 108b shows a sudden downward trend toward the contact layer 107;

[0068] The peak position of the bandgap width of the upper confinement layer 106 shows a slowly decreasing trend toward the active layer 103;

[0069] The peak position of the bandgap width of the lower confinement layer 101 shows a gradually decreasing trend toward the substrate 100 .

[0070] Furthermore, the descending angle ω of the peak position of the bandgap width of the first kink suppression layer 108a toward the substrate 100 is: 15°≤ω≤60°, the descending angle δ of the peak position of the bandgap width of the second kink suppression layer 108b toward the contact layer 107 is: 45°≤δ≤90°, the descending angle ψ of the peak position of the bandgap width of the upper confinement layer 106 toward the active layer 103 is: 0°≤ψ≤30°, the descending angle ε of the peak position of the bandgap width of the lower confinement layer 101 toward the substrate 100 is: 0°≤ε≤30°, and ε≤ψ≤ω≤δ.

[0071] In some optional embodiments, the first kink suppression layer 108a, the second kink suppression layer 108b, the upper confinement layer 106 and the lower confinement layer 101 all have peak rate electric field characteristics, and the peak rate electric field in the first kink suppression layer 108a, the second kink suppression layer 108b, the upper confinement layer 106 and the lower confinement layer 101 also has a certain variation trend, which is specifically manifested as follows:

[0072] The peak position of the peak rate electric field of the first kink suppression layer 108a shows a gradual downward trend toward the substrate 100;

[0073] The peak position of the peak rate electric field of the second kink suppression layer 108b shows a sudden downward trend toward the contact layer 107;

[0074] The peak position of the peak rate electric field of the upper confinement layer 106 shows a slowly decreasing trend toward the active layer 103;

[0075] The peak position of the peak rate electric field of the lower confinement layer 101 shows a gradually decreasing trend toward the substrate 100 .

[0076] Furthermore, the decreasing angle μ of the peak position of the peak rate electric field of the first kink suppression layer 108a toward the substrate 100 is: 15°≤μ≤60°, the decreasing angle ρ of the peak position of the peak rate electric field of the second kink suppression layer 108b toward the contact layer 107 is: 45°≤ρ≤90°, the decreasing angle υ of the peak position of the peak rate electric field of the upper confinement layer 106 toward the active layer 103 is: 0°≤υ≤30°, the decreasing angle χ of the peak position of the peak rate electric field of the lower confinement layer 101 toward the substrate 100 is: 0°≤χ≤30°, and χ≤υ≤μ≤ρ.

[0077] In some optional embodiments, the first kink suppression layer 108a, the second kink suppression layer 108b, the upper confinement layer 106 and the lower confinement layer 101 all have separation energy characteristics, and the separation energy in the first kink suppression layer 108a, the second kink suppression layer 108b, the upper confinement layer 106 and the lower confinement layer 101 also has a certain variation trend, which is specifically manifested as follows:

[0078] The peak position of the separation energy of the first kink suppression layer 108a shows a gradual downward trend toward the substrate 100;

[0079] The peak position of the separation energy of the second kink suppression layer 108b shows a sudden downward trend toward the contact layer 107;

[0080] The peak position of the separation energy of the upper confinement layer 106 shows a slowly decreasing trend toward the active layer 103;

[0081] The peak position of the separation energy of the lower confinement layer 101 shows a gradually decreasing trend toward the substrate 100 .

[0082] Furthermore, the decreasing angle κ of the peak position of the separation energy of the first kink suppression layer 108a toward the substrate 100 is: 15°≤κ≤60°, the decreasing angle ζ of the peak position of the separation energy of the second kink suppression layer 108b toward the contact layer 107 is: 45°≤ζ≤90°, the decreasing angle τ of the peak position of the separation energy of the upper confinement layer 106 toward the active layer 103 is: 0°≤τ≤30°, the decreasing angle π of the peak position of the separation energy of the lower confinement layer 101 toward the substrate 100 is: 0°≤π≤30°, and π≤τ≤ζ≤κ.

[0083] Furthermore, the relationship among the decreasing angle α of the peak position of the electron effective mass of the first kink suppression layer 108a toward the substrate 100, the decreasing angle ω of the peak position of the bandgap width of the first kink suppression layer 108a toward the substrate 100, the decreasing angle μ of the peak position of the peak rate electric field of the first kink suppression layer 108a toward the substrate 100, and the decreasing angle κ of the peak position of the separation energy of the first kink suppression layer 108a toward the substrate 100 is: 15°≤κ≤α≤ω≤μ≤60°.

[0084] The relationship between the decreasing angle β of the peak position of the electron effective mass of the second kink suppression layer 108b toward the contact layer 107, the decreasing angle δ of the peak position of the bandgap width of the second kink suppression layer 108b toward the contact layer 107, the decreasing angle ρ of the peak position of the peak rate electric field of the second kink suppression layer 108b toward the contact layer 107, and the decreasing angle ζ of the peak position of the separation energy of the second kink suppression layer 108b toward the contact layer 107 is: 45°≤ζ≤β≤δ≤ρ≤90°.

[0085] In some optional embodiments, the electron effective mass distribution characteristics, the bandgap width distribution characteristics, the peak rate electric field distribution characteristics and the separation energy distribution characteristics are further set in the first kink suppression layer 108a and the second kink suppression layer 108b, which are specifically manifested as follows:

[0086] The electron effective mass of the first kink suppression layer 108a has the function y1=A+B*sinx1 / x1 2 The third quadrant curve distribution;

[0087] The electron effective mass of the second kink suppression layer 108b has a curve distribution of function y2=C+D*lnx2+x2;

[0088] The bandgap of the first kink suppression layer 108a has the function y3=E+F*sinx1 / x1 2 The third quadrant curve distribution;

[0089] The bandgap of the second kink suppression layer 108b has a function y4=G+H*lnx2+x2 curve distribution;

[0090] The peak rate electric field of the first kink suppression layer 108a has the function y5=J+K*sinx1 / x1 2 The third quadrant curve distribution;

[0091] The peak rate electric field of the second kink suppression layer 108b has a function y6=L+M*lnx2+x2 curve distribution;

[0092] The separation energy of the first kink suppression layer 108a has the function y7=N+P*sinx1 / x1 2 The third quadrant curve distribution;

[0093] The separation energy of the second kink suppression layer 108b has a function y8=Q+R*lnx2+x2 curve distribution;

[0094] Wherein, x1 is the depth of the first kink suppression layer 108a toward the lower limiting layer 101, x2 is the depth of the second kink suppression layer 108b toward the contact layer 107, A≤E≤N≤J, C≤G≤Q≤L, and A≤C≤E≤G≤N≤Q≤J≤L.

[0095] This embodiment can control the lateral confinement and lateral expansion confinement of the carriers injected into the active layer 103 by designing the electron effective mass distribution characteristics, the bandgap width distribution characteristics, the peak rate electric field distribution characteristics and the separation energy distribution characteristics in the first kink suppression layer 108a and the second kink suppression layer 108b, thereby improving the light field confinement of the stimulated radiation field, suppressing the fluctuation of the polarization state in the propagation direction, reducing the probability of the radiation mode jumping from the fundamental mode to the higher-order mode, reducing the inter-mode variation of the longitudinal mode, improving the temporal coherence of the laser, improving the far-field image quality, reducing the vertical divergence angle, making the far-field light spot elliptical, and improving the beam quality factor.

[0096] In some optional embodiments, the first kink suppression layer 108a and the second kink suppression layer 108b are any one or any combination of InGaN, InN, AlInGaN, GaN, AlGaN, InGaN / GaN superlattice, InGaN / AlInN superlattice, InGaN / AlGaN superlattice, InGaN / AlInGaN superlattice, GaN / AlInN superlattice, GaN / AlGaN superlattice, InGaN / InGaN superlattice, AlInGaN / AlInGaN superlattice or any combination with GaN.

[0097] In some optional embodiments, the active layer 103 is a periodic structure composed of a well layer and a barrier layer, the number of periods is 3≥m≥1, and m can be 1, 2, or 3.

[0098] Specifically, the well layer is 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 has a thickness of 10 to 150 angstroms.

[0099] The barrier layer is 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, with a thickness of 10 to 200 angstroms.

[0100] Preferably, the lower confinement layer 101, the lower waveguide layer 102, the upper waveguide layer 104, the electron blocking layer 105, and the upper confinement layer 106 are 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.

[0101] Preferably, the substrate 100 is a single crystal substrate, such as sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, sapphire / SiN x , Sapphire / SiO2 / SiN x Composite substrate, sapphire / SiNx Any one of a / SiO2 composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0102] The following table is a parameter comparison of the epitaxial structure of a conventional semiconductor laser and the nitride semiconductor laser with a kink suppression layer proposed in this embodiment, including thermal inversion current density, kink critical current, beam quality factor, and slow axis divergence angle, showing the difference between the epitaxial structure of a conventional semiconductor laser and the nitride semiconductor laser with a kink suppression layer proposed in this embodiment:

[0103]

[0104] It can be seen that the epitaxial structure of the nitride semiconductor laser with a kink suppression layer proposed in this embodiment improves the thermal reversal current density, kink critical current, and beam quality factor compared with traditional semiconductor lasers, and the slow axis divergence angle is also well improved, which has obvious advantages over traditional semiconductor lasers.

[0105] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. An epitaxial structure of a nitride semiconductor laser with a kink suppression layer, comprising a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, an upper confinement layer and a contact layer arranged in sequence from bottom to top, characterized in that: A first kink suppression layer is arranged between the lower restriction layer and the substrate, and a second kink suppression layer is arranged between the upper restriction layer and the contact layer. The peak position of the Al element concentration of the first kink suppression layer decreases at an angle of 15° to 60° toward the substrate, the peak position of the H element concentration of the first kink suppression layer decreases at an angle of 30° to 90° toward the substrate, the peak position of the C element concentration of the first kink suppression layer decreases at an angle of 0° to 45° toward the substrate, the peak position of the O element concentration of the first kink suppression layer decreases at an angle of 0° to 45° toward the substrate, and the second kink suppression layer decreases at an angle of 15° to 60° toward the substrate. The descending angle of the peak position of the Al element concentration of the second kink suppression layer toward the contact layer is 45° to 90°, the rising angle of the valley value position of the In element concentration of the second kink suppression layer toward the contact layer is 45° to 90°, the rising angle of the valley value position of the H element concentration of the second kink suppression layer toward the contact layer is 30° to 90°, the rising angle of the valley value position of the C element concentration of the second kink suppression layer toward the contact layer is 0° to 45°, and the rising angle of the valley value position of the O element concentration of the second kink suppression layer toward the contact layer is 30° to 90°, and the angles are the tangent inclination angles along the curve.

2. The epitaxial structure of a nitride semiconductor laser having a kink suppression layer according to claim 1, wherein: The descending angle of the Al element concentration peak position of the first kink suppression layer toward the substrate is ≤ the descending angle of the Al element concentration peak position of the second kink suppression layer toward the contact layer is ≤ the rising angle of the In element concentration valley position of the second kink suppression layer toward the contact layer.

3. The epitaxial structure of a nitride semiconductor laser having a kink suppression layer according to claim 1, wherein: The descending angle of the peak position of the C element concentration of the first kink suppression layer toward the substrate is ≤ the descending angle of the peak position of the O element concentration of the first kink suppression layer toward the substrate is ≤ the descending angle of the peak position of the Al element concentration of the first kink suppression layer toward the substrate is ≤ the descending angle of the peak position of the H element concentration of the first kink suppression layer toward the substrate; The rising angle of the valley value position of the C element concentration of the second kink suppression layer toward the contact layer is ≤ the rising angle of the valley value position of the H element concentration of the second kink suppression layer toward the contact layer is ≤ the rising angle of the valley value position of the O element concentration of the second kink suppression layer toward the contact layer is ≤ the falling angle of the peak position of the Al element concentration of the second kink suppression layer toward the contact layer is ≤ the rising angle of the valley value position of the In element concentration of the second kink suppression layer toward the contact layer.

4. The epitaxial structure of a nitride semiconductor laser having a kink suppression layer according to claim 1, wherein: The first kink suppression layer, the second kink suppression layer, the upper confinement layer and the lower confinement layer all have electron effective mass characteristics. The decreasing angle α of the peak position of the electron effective mass of the first kink suppression layer toward the substrate is: 15°≤α≤60°, the decreasing angle β of the peak position of the electron effective mass of the second kink suppression layer toward the contact layer is: 45°≤β≤90°, the decreasing angle γ of the peak position of the electron effective mass of the upper confinement layer toward the active layer is: 0°≤γ≤30°, the decreasing angle θ of the peak position of the electron effective mass of the lower confinement layer toward the substrate is: 0°≤θ≤30°, and θ≤γ≤α≤β.

5. The epitaxial structure of a nitride semiconductor laser having a kink suppression layer according to claim 4, characterized in that: The first kink suppression layer, the second kink suppression layer, the upper confinement layer and the lower confinement layer all have bandgap width characteristics, the descending angle ω of the peak position of the bandgap width of the first kink suppression layer toward the substrate direction is: 15°≤ω≤60°, the descending angle δ of the peak position of the bandgap width of the second kink suppression layer toward the contact layer direction is: 45°≤δ≤90°, the descending angle ψ of the peak position of the bandgap width of the upper confinement layer toward the active layer direction is: 0°≤ψ≤30°, the descending angle ε of the peak position of the bandgap width of the lower confinement layer toward the substrate direction is: 0°≤ε≤30°, and ε≤ψ≤ω≤δ.

6. The epitaxial structure of a nitride semiconductor laser having a kink suppression layer according to claim 5, characterized in that: The first kink suppression layer, the second kink suppression layer, the upper confinement layer and the lower confinement layer all have peak rate electric field characteristics. The decreasing angle μ of the peak position of the peak rate electric field of the first kink suppression layer toward the substrate is: 15°≤μ≤60°, the decreasing angle ρ of the peak position of the peak rate electric field of the second kink suppression layer toward the contact layer is: 45°≤ρ≤90°, the decreasing angle υ of the peak position of the peak rate electric field of the upper confinement layer toward the active layer is: 0°≤υ≤30°, the decreasing angle χ of the peak position of the peak rate electric field of the lower confinement layer toward the substrate is: 0°≤χ≤30°, and χ≤υ≤μ≤ρ.

7. The epitaxial structure of a nitride semiconductor laser having a kink suppression layer according to claim 6, characterized in that: The first kink suppression layer, the second kink suppression layer, the upper confinement layer and the lower confinement layer all have separation energy characteristics. The decreasing angle κ of the peak position of the separation energy of the first kink suppression layer toward the substrate is: 15°≤κ≤60°, the decreasing angle ζ of the peak position of the separation energy of the second kink suppression layer toward the contact layer is: 45°≤ζ≤90°, the decreasing angle τ of the peak position of the separation energy of the upper confinement layer toward the active layer is: 0°≤τ≤30°, the decreasing angle π of the peak position of the separation energy of the lower confinement layer toward the substrate is: 0°≤π≤30°, and π≤τ≤ζ≤κ.

8. The epitaxial structure of a nitride semiconductor laser having a kink suppression layer according to claim 7, characterized in that: The relationship between the decreasing angle α of the peak position of the electron effective mass of the first kink suppression layer toward the substrate, the decreasing angle ω of the peak position of the bandgap width of the first kink suppression layer toward the substrate, the decreasing angle μ of the peak position of the peak rate electric field of the first kink suppression layer toward the substrate, and the decreasing angle κ of the peak position of the separation energy of the first kink suppression layer toward the substrate is: 15°≤κ≤α≤ω≤μ≤60°; The relationship between the decreasing angle β of the peak position of the electron effective mass of the second kink suppression layer toward the contact layer, the decreasing angle δ of the peak position of the bandgap width of the second kink suppression layer toward the contact layer, the decreasing angle ρ of the peak position of the peak rate electric field of the second kink suppression layer toward the contact layer, and the decreasing angle ζ of the peak position of the separation energy of the second kink suppression layer toward the contact layer is: 45°≤ζ≤β≤δ≤ρ≤90°.

9. The epitaxial structure of a nitride semiconductor laser having a kink suppression layer according to claim 1, wherein: The electron effective mass of the first kink suppression layer has the function y1=A+B*sinx1 / x1 2 The curve distribution in the third quadrant, the electron effective mass of the second kink suppression layer has the function y2=C+D*lnx2+x2 curve distribution, and the band gap width of the first kink suppression layer has the function y3=E+F*sinx1 / x1 2 The third quadrant curve distribution, the bandgap width of the second kink suppression layer has a function y4 = G + H * lnx2 + x2 curve distribution, the peak rate electric field of the first kink suppression layer has a function y5 = J + K * sinx1 / x1 2 The third quadrant curve distribution, the peak rate electric field of the second kink suppression layer has a function y6 = L + M * lnx2 + x2 curve distribution, the separation energy of the first kink suppression layer has a function y7 = N + P * sinx1 / x1 2 The third quadrant curve distribution, the separation energy of the second kink suppression layer has a function y8=Q+R*lnx2+x2 curve distribution, wherein x1 is the depth of the first kink suppression layer toward the lower limiting layer, x2 is the depth of the second kink suppression layer toward the contact layer, A≤E≤N≤J, C≤G≤Q≤L, and A≤C≤E≤G≤N≤Q≤J≤L.

10. The epitaxial structure of a nitride semiconductor laser having a kink suppression layer according to claim 1, wherein: The first kink suppression layer and the second kink suppression layer are any one or any combination of InGaN, InN, AlInGaN, GaN, AlGaN, InGaN / GaN superlattice, InGaN / AlInN superlattice, InGaN / AlGaN superlattice, InGaN / AlInGaN superlattice, GaN / AlInN superlattice, GaN / AlGaN superlattice, InGaN / InGaN superlattice, AlInGaN / AlInGaN superlattice or any combination with GaN; The active layer is a periodic structure composed of a well layer and a barrier layer, the number of periods is 3≥m≥1, and the well layer is 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 , with a thickness of 10 angstroms to 150 angstroms; the barrier layer is 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, with a thickness of 10 angstroms to 200 angstroms; The lower confinement layer, the lower waveguide layer, the upper waveguide layer, the electron blocking layer, and the upper confinement layer are 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, such as sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, sapphire / SiN x , Sapphire / SiO2 / SiN x Composite substrate, sapphire / SiN x Any one of a / SiO2 composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

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