A gallium nitride-based semiconductor laser having a graded peak rate electric field waveguide layer

Abstract

This invention proposes a gallium nitride-based semiconductor laser with a gradient peak rate electric field waveguide layer. The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the peak rate electric field distribution, and the fitting curve of the saturated electron drift velocity distribution obtained from SIMS testing of the upper and lower waveguide layers with the gradient peak rate electric field all satisfy any one of the Logistic function, Logistic 5 function, or Nelder function, forming a high electric field barrier. Electrons transporting from the active region to the p-type layer must overcome this barrier height, suppressing electron leakage from the active region to the p-type layer. The low electric field matches the low-velocity transport of holes, avoiding enhanced hole scattering. High injection efficiency allows carriers in the active region to quickly reach the stimulated emission threshold. The saturated electron drift velocity gradually decreases from high to low, and the low saturated electron drift velocity on the active region side avoids punch-through leakage caused by high-speed electrons rushing through the active region.

Description

Technical Field

[0001] This application relates to the field of semiconductor optoelectronic devices, and more particularly to a gallium nitride-based semiconductor laser with a gradient peak rate electric field waveguide layer. 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] Lasers and nitride semiconductor light-emitting diodes (LEDs) differ significantly:

[0004] 1) Lasers are generated by stimulated emission of charge carriers. They have a small half-width at half-maximum and very high brightness. The output power of a single laser can be in the W range. In contrast, nitride semiconductor light-emitting diodes are generated by spontaneous emission. The output power of a single light-emitting diode is in the mW range.

[0005] 2) The operating current density of lasers reaches KA / cm2, which is more than two orders of magnitude higher than that of nitride light-emitting diodes. This results in stronger electron leakage, more severe Auger recombination, stronger polarization effect, and more severe electron-hole mismatch, leading to more severe efficiency degradation and the Droop effect.

[0006] 3) Light-emitting diodes emit spontaneous transition radiation, which is incoherent light that transitions from a high energy level to a low energy level without external influence. In contrast, lasers emit stimulated transition radiation, where the energy of the induced photon should be equal to the energy difference of the electron transition, producing coherent light that is identical to the induced photon.

[0007] 4) Different principles: Light emission diodes emit light by electrons and holes jumping to the active layer or pn junction under the action of external voltage to generate radiative recombination, while lasers require certain lasing conditions to be met before they can emit light. This requires the carriers in the active region to be reversed, the stimulated emission light to oscillate back and forth in the resonant cavity, and the propagation in the gain medium to amplify the light. When the threshold condition is met, the gain is greater than the loss, and finally, laser light is output.

[0008] Nitride semiconductor lasers have the following problems: lasers with traditional uniform waveguide layers suffer from problems such as electric field concentration, premature electron saturation, carrier leakage, and field-induced optical field distortion; electric field concentration in the uniform waveguide layer can cause refractive index distribution distortion, which in turn leads to optical field mode jumps and increased divergence angle; the high electric field in the uniform upper waveguide layer can exacerbate hole scattering, resulting in low hole injection efficiency (30%~40%), electron accumulation in the active region, and enhanced nonradiative recombination. Summary of the Invention

[0009] To address one of the aforementioned technical problems, this invention provides a gallium nitride-based semiconductor laser with a gradient peak rate electric field waveguide layer.

[0010] This invention provides a gallium nitride-based semiconductor laser with a gradient peak rate electric field waveguide layer, comprising, from bottom to top, a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, a first upper confinement layer, an electron blocking layer, a second upper confinement layer, and a contact layer. The lower waveguide layer includes a first lower waveguide layer and a second lower waveguide layer, with the first lower waveguide layer located below the second lower waveguide layer. The first lower waveguide layer is a constant peak rate electric field waveguide layer, and the second lower waveguide layer is a gradient peak rate electric field waveguide layer. The upper waveguide layer includes a first upper waveguide layer and a second upper waveguide layer, with the first upper waveguide layer located below the second upper waveguide layer. The first upper waveguide layer is a gradient peak rate electric field waveguide layer, and the second upper waveguide layer is a constant peak rate electric field waveguide layer.

[0011] The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the peak rate electric field distribution, and the fitting curve of the saturated electron drift velocity distribution of the waveguide layer under the gradient peak rate electric field test all satisfy any one of the Logistic function, Logistic5 function, or Nelder function.

[0012] The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the peak rate electric field distribution, and the fitting curve of the saturated electron drift velocity distribution of the waveguide layer under the SIMS test under the gradually varying peak rate electric field all satisfy any one of the Logistic function, Logistic5 function, or Nelder function.

[0013] Preferably, when the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS on the gradient peak rate electric field satisfies the Logistic function, the Logistic function is y1=A2+(A1-A2) / (1+(x1 / B)^C), where y1 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS on the gradient peak rate electric field; x1 is the thickness of the waveguide layer on the gradient peak rate electric field; A2 is the saturation limit value; A1 is the initial limit value; B is the threshold characteristic parameter; and C is the transition rate parameter, wherein: 1.5E15≤A2≤1.5E26, -3.5E26≤A1≤0, 0.007≤B≤700, and 0.002≤C≤200;

[0014] When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test under the gradient peak rate electric field satisfies the Logistic function, the Logistic function is y2=F2+(F1-F2) / (1+(x2 / G)^H), where y2 is the In ion intensity or In atom concentration of the waveguide layer under the SIMS test under the gradient peak rate electric field; x2 is the thickness of the waveguide layer under the gradient peak rate electric field; F2 is the saturation limit value; F1 is the initial limit value; G is the threshold characteristic parameter; and H is the transition rate parameter, where: -4.9E26≤F2≤0, 1.8E15≤F1≤1.8E26, 0.002≤G≤200, and 0.002≤H≤200.

[0015] Preferably, when the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS on the gradient peak rate electric field satisfies the Logistic 5 function, the Logistic 5 function is y3=J2+(J1-J2) / (1+(K / x1)^M)^N, where y3 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS on the gradient peak rate electric field; x1 is the thickness of the waveguide layer on the gradient peak rate electric field; J2 is the lower asymptote parameter; J1 is the upper asymptote parameter; K is the midpoint characteristic parameter; M is the rise rate parameter; and N is the saturation shape correction parameter, wherein: -4.9E26≤J2≤400, 6.5E15≤J1≤6.5E26, 0.006≤K≤600, 0.01≤M≤10000, and 0.001≤N≤1000;

[0016] When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test under the gradient peak rate electric field satisfies the Logistic5 function, the Logistic5 function is y4=P2+(P1-P2) / (1+(Q / x2)^R)^S, where y4 is the In ion intensity or In atom concentration of the waveguide layer under the SIMS test under the gradient peak rate electric field; x2 is the thickness of the waveguide layer under the gradient peak rate electric field; P2 is the lower asymptote parameter; P1 is the upper asymptote parameter; Q is the midpoint characteristic parameter; R is the rise rate parameter; and S is the saturation shape correction parameter, where: -7E26≤P2≤700, 2E15≤P1≤2E26, 0.001≤Q≤100, -10000≤R≤100, and 0.0006≤S≤6000.

[0017] Preferably, when the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS on the gradient peak rate electric field satisfies the Nelder function, the Nelder function is y5=(x1+T) / (U0+U1*(x1+T)+U2*(x1+T)^2), where y5 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS on the gradient peak rate electric field; x1 is the thickness of the waveguide layer on the gradient peak rate electric field; T is the independent variable offset parameter; U0 is the attenuation coefficient of the low independent variable segment; U1 is the linear gain coefficient; and U2 is the attenuation coefficient of the high independent variable segment; wherein: -4000≤T≤400, 5E-28≤U0≤5E-17, -4E-22≤U1≤400, 1E-27≤U2≤1E-16;

[0018] When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test under the gradient peak rate electric field satisfies the Nelder function, the Nelder function is y6=(x2+V) / (W0+W1*(x2+V)+W2*(x2+V)^2), where y6 is the In ion intensity or In atom concentration of the waveguide layer under the SIMS test under the gradient peak rate electric field; x2 is the thickness of the waveguide layer under the gradient peak rate electric field; V is the independent variable offset parameter; W0 is the attenuation coefficient of the low independent variable segment; W1 is the linear gain coefficient; and W2 is the attenuation coefficient of the high independent variable segment; wherein: -8000≤V≤800, -4E-17≤W0≤400, 5E-27≤W1≤5E-17, and 2E-26≤W2≤2E-16.

[0019] Preferably, when the fitting curve of the peak velocity electric field distribution of the waveguide layer on the gradually varying peak velocity electric field satisfies the Logistic function, the Logistic function is y7=a2+(a1-a2) / (1+(x1 / b)^c), where y7 is the peak velocity electric field of the waveguide layer on the gradually varying peak velocity electric field; x1 is the thickness of the waveguide layer on the gradually varying peak velocity electric field; a2 is the saturation limit value; a1 is the initial limit value; b is the threshold characteristic parameter; and c is the transition rate parameter, wherein: 0.05≤a2≤50000, 0.01≤a1≤100000, 0.0007≤b≤700, and 0.002≤c≤200;

[0020] When the fitted curve of the peak rate electric field distribution of the waveguide layer under the gradient peak rate electric field satisfies the Logistic function, the Logistic function is y8=f2+(f1-f2) / (1+(x2 / g)^h), where y8 is the peak rate electric field of the waveguide layer under the gradient peak rate electric field; x2 is the thickness of the waveguide layer under the gradient peak rate electric field; f2 is the saturation limit value; f1 is the initial limit value; g is the threshold characteristic parameter; and h is the transition rate parameter, where: 0.04≤f2≤400000, 0.04≤f1≤400000, 0.002≤g≤200, and 0.001≤h≤100.

[0021] Preferably, when the fitting curve of the peak velocity electric field distribution of the waveguide layer on the gradient peak velocity electric field satisfies the Logistic5 function, the Logistic5 function is y9=j2+(j1-j2) / (1+(k / x1)^m)^n, where y9 is the peak velocity electric field of the waveguide layer on the gradient peak velocity electric field; x1 is the thickness of the waveguide layer on the gradient peak velocity electric field; j2 is the lower asymptote parameter; j1 is the upper asymptote parameter; k is the midpoint characteristic parameter; m is the rise rate parameter; and n is the saturation shape correction parameter, wherein: 0.02≤j2≤2000000, 0.006≤j1≤60000, 0.00086≤k≤8000, -20000≤m≤200, and 0.002≤n≤20000;

[0022] When the fitted curve of the peak velocity electric field distribution of the waveguide layer under the gradually varying peak velocity electric field satisfies the Logistic5 function, the Logistic5 function is y 10 =p2+(p1-p2) / (1+(q / x2)^r)^s,y 10 denoted as q, where q is the peak velocity electric field of the waveguide layer under a gradient peak velocity electric field; x2 is the thickness of the waveguide layer under a gradient peak velocity electric field; p2 is the lower asymptote parameter; p1 is the upper asymptote parameter; q is the midpoint characteristic parameter; r is the rise rate parameter; and s is the saturation shape correction parameter. Where: 0.004≤p2≤40000, 0.06≤p1≤6000000, 0.001≤q≤1000, 0.00009≤r≤900, and 0.0001≤s≤10000.

[0023] Preferably, when the fitting curve of the peak velocity electric field distribution of the waveguide layer on the gradually varying peak velocity electric field satisfies the Nelder function, the Nelder function is y 11 =(x1+t) / (u0+u1*(x1+t)+u2*(x1+t)^2),y 11Let be the peak velocity electric field of the waveguide layer over the gradually varying peak velocity electric field; x1 be the thickness of the waveguide layer over the gradually varying peak velocity electric field; t be the independent variable offset parameter; u0 be the attenuation coefficient in the low independent variable segment; u1 be the linear gain coefficient; and u2 be the attenuation coefficient in the high independent variable segment. Where: -5000≤t≤500, -1E-3≤u0≤-1E-13, 0.000008≤u1≤800, and 0.000008≤u2≤800.

[0024] When the fitted curve of the peak velocity electric field distribution of the waveguide layer under the gradually varying peak velocity electric field satisfies the Nelder function, the Nelder function is y 12 =(x2+v) / (w0+w1*(x2+v)+w2*(x2+v)^2),y 12 denoted as , where is the peak velocity electric field of the waveguide layer under a gradually varying peak velocity electric field; x2 is the thickness of the waveguide layer under the gradually varying peak velocity electric field; v is the independent variable offset parameter; w0 is the attenuation coefficient in the low independent variable segment; w1 is the linear gain coefficient; and w2 is the attenuation coefficient in the high independent variable segment. Where: -6000≤v≤800, 1E-16≤w0≤1-E3, 0.000008≤w1≤800, -600≤w2≤-0.000006.

[0025] Preferably, when the fitting curve of the saturated electron drift velocity distribution of the waveguide layer on the gradually varying peak rate electric field satisfies the Logistic function, the Logistic function is y 13 =a2'+(a1'-a2') / (1+(x1 / b')^c'),y 13 denoted as saturated electron drift velocity of the waveguide layer under a gradually increasing peak rate electric field; x1 is the thickness of the waveguide layer under the gradually increasing peak rate electric field; a2' is the saturation limit; a1' is the initial limit; b' is the threshold characteristic parameter, i.e., the core critical value of the transition process; and c' is the transition rate parameter that determines the steepness and shape factor of the curve, where: 4E3≤a2'≤4E13, 2E3≤a1'≤2E13, 0.0007≤b'≤700, and 0.002≤c'≤200.

[0026] When the fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually varying peak rate electric field satisfies the Logistic function, the Logistic function is y 14 =f2'+(f1'-f2') / (1+(x2 / g')^h'),y 14denoted as saturated electron drift velocity of the waveguide layer under a gradually varying peak rate electric field; x2 is the thickness of the waveguide layer under a gradually varying peak rate electric field; f2' is the saturation limit; f1' is the initial limit; g' is the threshold characteristic parameter; and h' is the transition rate parameter, where: -1E13≤f2'≤100, 4E3≤f1'≤4E13, 0.002≤g'≤2000, and 0.001≤h'≤100.

[0027] Preferably, when the fitting curve of the saturated electron drift velocity distribution of the waveguide layer on the gradually varying peak rate electric field satisfies the Logistic 5 function, the Logistic 5 function is y 15 =j2'+(j1'-j2') / (1+(k' / x1)^m')^n', y 15 denoted as , where is the saturated electron drift velocity of the waveguide layer under the gradient peak velocity electric field; x1 is the thickness of the waveguide layer under the gradient peak velocity electric field; j2' is the lower asymptote parameter; j1' is the upper asymptote parameter; k' is the midpoint characteristic parameter; m' is the rise rate parameter; and n' is the saturation shape correction parameter, where: 2E3≤j2'≤2E13, 3E3≤j1'≤3E13, 0.0006≤k'≤6000, 0.00001≤m'≤1000, and 0.0001≤n'≤1000.

[0028] When the fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually varying peak rate electric field satisfies the Logistic 5 function, the Logistic 5 function is y 16 =p2'+(p1'-p2') / (1+(q' / x2)^r')^s',y 16 q' is the saturated electron drift velocity of the waveguide layer under a gradient peak rate electric field; x2 is the thickness of the waveguide layer under a gradient peak rate electric field; p2' is the lower asymptote parameter; p1' is the upper asymptote parameter; q' is the midpoint characteristic parameter; r' is the rise rate parameter; and s' is the saturation shape correction parameter, where: -3E13≤p2'≤300, 4E3≤p1'≤4E13, 0.001≤q'≤1000, -1000≤r'≤100, and 0.0006≤s'≤60000.

[0029] Preferably, when the fitting curve of the saturated electron drift velocity distribution of the waveguide layer on the gradually varying peak rate electric field satisfies the Nelder function, the Nelder function is y 17 =(x1+t') / (u0'+u1'*(x1+t')+u2'*(x1+t')^2), y 17denoted as saturated electron drift velocity of the waveguide layer under a gradually increasing peak velocity electric field; x1 is the thickness of the waveguide layer under the gradually increasing peak velocity electric field; t' is the independent variable offset parameter; u0' is the attenuation coefficient in the low independent variable segment; u1' is the linear gain coefficient; u2' is the attenuation coefficient in the high independent variable segment; where: -0.00004≤t'≤4000, 5E-16≤u0'≤5E-3, 3E-13≤u1'≤3E-3, -3E-3≤u2'≤-3E-13;

[0030] When the fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually varying peak rate electric field satisfies the Nelder function, the Nelder function is y 18 =(x2+v') / (w0'+w1'*(x2+v')+w2'*(x2+v')^2), y 18 denoted as saturated electron drift velocity of the waveguide layer under a gradually increasing peak velocity electric field; x2 is the thickness of the waveguide layer under a gradually increasing peak velocity electric field; v' is the independent variable offset parameter; w0' is the attenuation coefficient in the low independent variable segment; w1' is the linear gain coefficient; w2' is the attenuation coefficient in the high independent variable segment; where: -8000≤v'≤800, -2E-8≤w0'≤-2E-19, 3E-13≤w1'≤3E-3, 1E-16≤w2'≤1E-3.

[0031] Preferably, the substrate is a GaN single crystal substrate;

[0032] The lower waveguide layer is any one or any combination of InGaN, GaN / InGaN, GaN / InGaN / GaN, InGaN / GaN, and GaN.

[0033] The active layer is an InGaN / GaN quantum well;

[0034] The upper waveguide layer is any one or any combination of InGaN, GaN / InGaN, GaN / InGaN / GaN, InGaN / GaN, and GaN.

[0035] The electron blocking layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN.

[0036] The lower confinement layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0037] The first upper confinement layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0038] The second upper confinement layer is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0039] The contact layer is any one or any combination of GaN, AlGaN, InGaN, and AlInGaN.

[0040] Preferably, the lower waveguide layer is a combination of GaN and InGaN;

[0041] The upper waveguide layer is an InGaN / GaN combination;

[0042] The upper confinement layer is an AlGaN / AlGaN combination;

[0043] The electron blocking layer is AlGaN;

[0044] The lower confinement layer is a combination of AlGaN / InGaN / AlGaN;

[0045] The first upper confinement layer is AlGaN;

[0046] The second upper confinement layer is an AlGaN / GaN combination;

[0047] The contact layer is a GaN / InGaN combination.

[0048] Preferably, the thickness of the lower waveguide layer is 300 angstroms to 8000 angstroms;

[0049] The thickness of the upper waveguide layer is 300 angstroms to 8000 angstroms;

[0050] The thickness of the upper confinement layer is 500 angstroms to 9000 angstroms;

[0051] The thickness of the electron blocking layer is from 5 angstroms to 800 angstroms;

[0052] The thickness of the lower confinement layer is from 500 angstroms to 80,000 angstroms;

[0053] The thickness of the first upper confinement layer is from 100 angstroms to 50,000 angstroms;

[0054] The thickness of the second upper confinement layer is from 100 angstroms to 50,000 angstroms;

[0055] The thickness of the contact layer is from 5 angstroms to 500 angstroms.

[0056] The beneficial effects of the present invention are as follows: The lower waveguide layer of the gallium nitride-based semiconductor laser in the present invention includes a first lower waveguide layer and a second lower waveguide layer, wherein the first lower waveguide layer is a constant peak rate electric field lower waveguide layer and the second lower waveguide layer is a gradient peak rate electric field lower waveguide layer; the upper waveguide layer includes a first upper waveguide layer and a second upper waveguide layer, wherein the first upper waveguide layer is a gradient peak rate electric field upper waveguide layer and the second upper waveguide layer is a constant peak rate electric field upper waveguide layer. In this invention, the fitting curves of In ion intensity distribution or In atom concentration distribution, peak rate electric field distribution, and saturated electron drift velocity distribution obtained from SIMS tests of the upper and lower waveguide layers under the gradient peak rate electric field all satisfy any one of the Logistic function, Logistic 5 function, or Nelder function, thereby forming a high electric field barrier. When electrons are transported from the active region to the p-type layer, they need to overcome the barrier height, reducing the reverse leakage rate by 70%~80% and suppressing electrons from the active region to the p-type layer in the reverse direction. At the same time, the low electric field matches the low-rate transport of holes, avoiding enhanced hole scattering. Meanwhile, the high injection efficiency enables the charge carriers in the active region to quickly reach the stimulated emission threshold, increasing the radiative recombination efficiency by 25%~40% and the internal quantum efficiency from 60%~70% to 80%~90%. The saturated electron drift velocity gradually decreases from high to low (from the upper waveguide layer towards the quantum well). The low saturated electron drift velocity on the active region side avoids punch-through leakage caused by high-speed electrons rushing through the active region, reducing the carrier leakage rate by 60%~70%. Attached Figure Description

[0057] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0058] Figure 1 This is a schematic diagram of the structure of a gallium nitride-based semiconductor laser with a gradient peak rate electric field waveguide layer according to an embodiment of the present invention;

[0059] Figure 2 The above are the SIMS secondary ion mass spectra and x, y coordinate diagrams of the gallium nitride-based semiconductor laser with a gradient peak rate electric field waveguide layer as described in the embodiments of the present invention.

[0060] Figure 3 The image shows the SIMS secondary ion mass spectrum of the waveguide layer with the gradient peak rate electric field of the gallium nitride-based semiconductor laser with the gradient peak rate electric field waveguide layer described in the embodiment of the present invention, and its Logistic function fitting curve.

[0061] Figure 4The image shows the SIMS secondary ion mass spectrum of the waveguide layer with the gradient peak rate electric field of the gallium nitride-based semiconductor laser with the gradient peak rate electric field waveguide layer described in the embodiment of the present invention, and its Logistic 5 function fitting curve.

[0062] Figure 5 The image shows the SIMS secondary ion mass spectrum of the waveguide layer with the gradient peak rate electric field of the gallium nitride-based semiconductor laser with the gradient peak rate electric field waveguide layer described in the embodiment of the present invention, and its Nelder function fitting curve.

[0063] Figure 6 The image shows the SIMS secondary ion mass spectrum of the waveguide layer of the gallium nitride-based semiconductor laser with a gradient peak rate electric field under the gradient peak rate electric field, as described in the embodiments of the present invention, and its Logistic function fitting curve.

[0064] Figure 7 The image shows the SIMS secondary ion mass spectrum of the waveguide layer of the gallium nitride-based semiconductor laser with a gradient peak rate electric field under the gradient peak rate electric field, as described in the embodiments of the present invention, and its Logistic 5 function fitting curve.

[0065] Figure 8 The image shows the SIMS secondary ion mass spectrum of the waveguide layer of the gallium nitride-based semiconductor laser with a graded peak rate electric field waveguide layer according to an embodiment of the present invention, and its Nelder function fitting curve.

[0066] Figure label:

[0067] 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.

[0068] 102a, First lower waveguide layer; 102b, Second lower waveguide layer;

[0069] 104a, First upper waveguide layer; 104b, Second upper waveguide layer;

[0070] 106a, First upper confinement layer; 106b, Second upper confinement layer. Detailed Implementation

[0071] To make the technical solutions and advantages of the embodiments of this application clearer, the exemplary embodiments of this application will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0072] like Figure 1 and Figure 2 As shown, this embodiment proposes a gallium nitride-based semiconductor laser with a gradient peak rate electric field waveguide layer, including 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 sequentially from bottom to top.

[0073] Specifically, in this embodiment, the gallium nitride-based semiconductor laser with a gradient peak rate electric field waveguide layer is provided from bottom to top 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. The upper confinement layer 106 includes a first upper confinement layer 106a and a second upper confinement layer 106b, which are located below and above the electron blocking layer 105, respectively.

[0074] In this embodiment, the lower waveguide layer 102 includes a first lower waveguide layer 102a and a second lower waveguide layer 102b, with the first lower waveguide layer 102a located below the second lower waveguide layer 102b. The first lower waveguide layer 102a is a constant peak rate electric field lower waveguide layer 102, and the second lower waveguide layer 102b is a gradient peak rate electric field lower waveguide layer. The upper waveguide layer 104 includes a first upper waveguide layer 104a and a second upper waveguide layer 104b, with the first upper waveguide layer 104a located below the second upper waveguide layer 104b. The first upper waveguide layer 104a is a gradient peak rate electric field upper waveguide layer, and the second upper waveguide layer 104b is a constant peak rate electric field upper waveguide layer 104.

[0075] Both the waveguide layer above and below the gradually varying peak rate electric field exhibit the In ion intensity distribution or In atom concentration distribution characteristics, peak rate electric field distribution characteristics, and saturated electron drift velocity distribution characteristics as measured by SIMS. Specifically, they are as follows:

[0076] The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the peak rate electric field distribution, and the fitting curve of the saturated electron drift velocity distribution of the waveguide layer under the gradient peak rate electric field test all satisfy any one of the Logistic function, Logistic5 function, or Nelder function.

[0077] The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the peak rate electric field distribution, and the fitting curve of the saturated electron drift velocity distribution of the waveguide layer under the SIMS test of the gradually varying peak rate electric field all satisfy any one of the Logistic function, Logistic5 function, or Nelder function.

[0078] The standard form of the asymmetric S-shaped growth and decay of the three-parameter Logistic function (3PL) (also often referred to as the extended form of the Sigmoid function).

[0079] The Logistic5 function is an inverse variable extension of the five-parameter Logistic (5PL) model (the independent variable exists in the form of K / x). It is a high-order modified version of the classic S-type Logistic model. Its core feature is to adapt to the nonlinear change characteristics of the dependent variable as x increases, from the initial value J2 to the later saturation to J1. It is a standardized high-order model for handling "rising-saturation" type curves in scientific data fitting.

[0080] The Nelder function is a second-order rational fractional Nelder model (also often called the Nelder-Mead rational fitting model), which belongs to the unimodal inverted U-shaped quasi-Lorentz nonlinear model. Its core fitting characteristic is that as the independent variable increases, the dependent variable first monotonically rises to the peak value and then monotonically decreases, exhibiting an asymmetric unimodal change.

[0081] The upper and lower waveguide layers of GaN-based lasers are the core coupling regions for electric field distribution, electron transport, optical field confinement, and thermal transport. Their gradient peak rate electric field (Ep) and gradient saturation electron drift velocity (vs) are spatially gradient-controlled through AlGaN composition gradients, doping distribution, or superlattice microstructures. This addresses the problems of electric field concentration, premature electron saturation, carrier leakage, and field-induced optical field distortion inherent in traditional uniform waveguide layers by controlling the electric field of carrier transport at its source. The lower waveguide layer, as the main electron transport channel, is the core region for gradient control, directly determining the laser's threshold, efficiency, response speed, and other core performance characteristics. The upper waveguide layer, as an electron leakage blocking layer and hole transport channel, is an auxiliary region for gradient control, its core function being to suppress reverse electron leakage and ensure device reliability. The gradient design of both follows the principle of functional differentiation, ultimately achieving synergistic optimization of electric field distribution, electron drift velocity, carrier injection, and optical field confinement, comprehensively improving laser performance. The low peak rate electric field on the active region side forms a low-field gradient distribution, matching the low mobility of holes, reducing hole transport scattering loss by 30%–40%, bringing the electron-to-hole concentration ratio in the active region closer to 1, reducing Auger recombination velocity by 15%–20%, and further improving internal quantum efficiency by 5%–8%. The peak rate electric field gradient keeps the electron drift velocity within the peak range, and the electron transport time τn increases from 10–15 p.m. The injection rate is reduced to 3-5 ps, the carrier injection rate is increased by 2-3 times, the relaxation oscillation frequency is increased by 2-3 times, and the modulation bandwidth is increased from 500 MHz to 1.5-2 GHz. The lower waveguide layer (the main electron transport channel) maintains the peak drift rate transport of electrons by gradually changing the peak rate electric field from low to high and from high to low, which greatly improves the injection efficiency, reduces the threshold, and improves efficiency and response speed. The upper waveguide layer (the electron leakage barrier layer) forms a high electric field barrier to suppress electron reverse leakage by gradually changing the peak rate electric field from high to low and from low to high. At the same time, the low electric field matches the hole transport, which improves the carrier utilization rate.

[0082] Specifically, in this embodiment, the fitting curves of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the gradient peak rate electric field SIMS test are as follows:

[0083] When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS on a gradually increasing peak rate electric field satisfies the Logistic function, the Logistic function is y1=A2+(A1-A2) / (1+(x1 / B)^C), where y1 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS on a gradually increasing peak rate electric field; x1 is the thickness of the waveguide layer on a gradually increasing peak rate electric field; A2 is the saturation limit; A1 is the initial limit; B is the threshold characteristic parameter, i.e., the core critical value of the transition process; and C is the transition rate parameter, which determines the steepness and shape factor of the curve, where: 1.5E15≤A2≤1.5E26, -3.5E26≤A1≤0, 0.007≤B≤700, and 0.002≤C≤200. Figure 3 As shown, the fitting curves of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test on the gradually increasing peak rate electric field can satisfy the Logistic function as y1=1.58664E21+(-3.50591E20-1.58664E21) / (1+(x1 / 0.70092)^2.62198).

[0084] When the fitted curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS over a gradually increasing peak rate electric field satisfies the Logistic 5 function, the Logistic 5 function is y3=J2+(J1-J2) / (1+(K / x1)^M)^N, where y3 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS over a gradually increasing peak rate electric field; x1 is the thickness of the waveguide layer over a gradually increasing peak rate electric field; J2 is the lower asymptote parameter (initial base value of the dependent variable); and J1... Let J be the upper asymptote parameter (upper limit of saturation for the dependent variable), K be the midpoint characteristic parameter (semi-saturated independent variable), M be the rate of ascent parameter (shape factor on the horizontal axis), which determines the steepness of the ascent segment of the dependent variable, and N be the saturation shape correction parameter (shape factor on the vertical axis), which determines the transition curvature between the ascent segment and the saturation segment. Where: -4.9E26≤J2≤400, 6.5E15≤J1≤6.5E26, 0.006≤K≤600, 0.01≤M≤10000, 0.001≤N≤1000. Figure 4 As shown, the fitting curves of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test on the gradually increasing peak rate electric field can satisfy the Logistic 5 function as y3=-4.90769E20+(6.51327E20+4.90769E20) / (1+(0.68098 / x1)^11.07916)^0.1393.

[0085] When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS on a gradually increasing peak rate electric field satisfies the Nelder function, the Nelder function is y5=(x1+T) / (U0+U1*(x1+T)+U2*(x1+T)^2), where y5 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS on a gradually increasing peak rate electric field; x1 is the thickness of the waveguide layer on a gradually increasing peak rate electric field; T is the independent variable offset parameter, whose core function is to correct the zero-point offset of the original independent variable; U0 is the attenuation coefficient in the low independent variable segment; U1 is the linear gain coefficient; and U2 is the attenuation coefficient in the high independent variable segment; where: -4000≤T≤400, 5E-28≤U0≤5E-17, -4E-22≤U1≤400, and 1E-27≤U2≤1E-16. Figure 5 As shown, the fitting curves of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test on the gradually increasing peak rate electric field can satisfy the Nelder function as y5=(x1-0.39405) / (5.23559E-22-4.16985E-22*(x1-0.39405)+1.17367E-21*(x1-0.39405)^2).

[0086] In this embodiment, the fitting curves of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the gradient peak rate electric field SIMS test are specifically as follows:

[0087] When the fitted curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS under a gradually increasing peak rate electric field satisfies the Logistic function, the Logistic function is y2=F2+(F1-F2) / (1+(x2 / G)^H), where y2 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS under a gradually increasing peak rate electric field; x2 is the thickness of the waveguide layer under a gradually increasing peak rate electric field; F2 is the saturation limit; F1 is the initial limit; G is the threshold characteristic parameter; and H is the transition rate parameter, where: -4.9E26≤F2≤0, 1.8E15≤F1≤1.8E26, 0.002≤G≤200, and 0.002≤H≤200. Figure 6 As shown, the fitting curves of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test under the gradually varying peak rate electric field can satisfy the Logistic function as y2=-4.96011E21+(1.88389E21+4.96011E21) / (1+(x2 / 1.74845)^1.22232).

[0088] When the fitted curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS under a graded peak rate electric field satisfies the Logistic 5 function, the Logistic 5 function is y4=P2+(P1-P2) / (1+(Q / x2)^R)^S, where y4 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS under a graded peak rate electric field; x2 is the thickness of the waveguide layer under a graded peak rate electric field; P2 is the lower asymptote parameter; P1 is the upper asymptote parameter; Q is the midpoint characteristic parameter; R is the rise rate parameter; and S is the saturation shape correction parameter, where: -7E26≤P2≤700, 2E15≤P1≤2E26, 0.001≤Q≤100, -10000≤R≤100, and 0.0006≤S≤6000. Figure 7 As shown, the fitting curves of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test under the gradient peak rate electric field can satisfy the Logistic 5 function as y4=-7.50405E21+(1.99476E21+7.50405E21) / (1+(1.78538 / x2)^(-1.11393))^0.69421.

[0089] When the fitting curves of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS under a graded peak rate electric field satisfy the Nelder function, the Nelder function is y6=(x2+V) / (W0+W1*(x2+V)+W2*(x2+V)^2), where y6 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS under a graded peak rate electric field; x2 is the thickness of the waveguide layer under a graded peak rate electric field; V is the independent variable offset parameter; W0 is the attenuation coefficient in the low independent variable segment; W1 is the linear gain coefficient; and W2 is the attenuation coefficient in the high independent variable segment; where: -8000≤V≤800, -4E-17≤W0≤400, 5E-27≤W1≤5E-17, and 2E-26≤W2≤2E-16. Figure 8 As shown, the fitting curves of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test under the gradually varying peak rate electric field can satisfy the Nelder function as y6=(x2-0.79015) / (-4.24208E-22+5.18262E-22*(x2-0.79015)+2.24813E-21*(x2-0.79015)^2).

[0090] In this embodiment, the fitting curve of the peak velocity electric field distribution of the waveguide layer on the gradually varying peak velocity electric field is specifically represented as follows:

[0091] When the fitted curve of the peak velocity electric field distribution of the waveguide layer under the gradient peak velocity electric field satisfies the Logistic function, the Logistic function is y7=a2+(a1-a2) / (1+(x1 / b)^c), where y7 is the peak velocity electric field of the waveguide layer under the gradient peak velocity electric field; x1 is the thickness of the waveguide layer under the gradient peak velocity electric field; a2 is the saturation limit value; a1 is the initial limit value; b is the threshold characteristic parameter; and c is the transition rate parameter, where: 0.05≤a2≤50000, 0.01≤a1≤100000, 0.0007≤b≤700, and 0.002≤c≤200. The fitting curve of the peak velocity electric field distribution of the waveguide layer under the gradually varying peak velocity electric field can satisfy the Logistic function as y7=45.7273+(173.04054-45.7273) / (1+(x1 / 0.70092)^2.62198).

[0092] When the fitting curve of the peak velocity electric field distribution of the waveguide layer under the gradient peak velocity electric field satisfies the Logistic5 function, the Logistic5 function is y9=j2+(j1-j2) / (1+(k / x1)^m)^n, where y9 is the peak velocity electric field of the waveguide layer under the gradient peak velocity electric field; x1 is the thickness of the waveguide layer under the gradient peak velocity electric field; j2 is the lower asymptote parameter; j1 is the upper asymptote parameter; k is the midpoint characteristic parameter; m is the rise rate parameter; and n is the saturation shape correction parameter, where: 0.02≤j2≤2000000, 0.006≤j1≤60000, 0.00086≤k≤8000, -20000≤m≤200, and 0.002≤n≤20000. The fitting curve of the peak velocity electric field distribution of the waveguide layer on the gradually varying peak velocity electric field can satisfy the Logistic 5 function as y9=64.49753+(173.27772-64.49753) / (1+(0.87474 / x1)^(-2.55106))^1.95898.

[0093] When the fitted curve of the peak velocity electric field distribution of the waveguide layer over a gradually varying peak velocity electric field satisfies the Nelder function, the Nelder function is y. 11 =(x1+t) / (u0+u1*(x1+t)+u2*(x1+t)^2),y 11Let be the peak velocity electric field of the waveguide layer over the gradually varying peak velocity electric field; x1 be the thickness of the waveguide layer over the gradually varying peak velocity electric field; t be the offset parameter; u0 be the attenuation coefficient in the low independent variable segment; u1 be the linear gain coefficient; and u2 be the attenuation coefficient in the high independent variable segment; where: -5000≤t≤500, -1E-3≤u0≤-1E-13, 0.000008≤u1≤800, and 0.000008≤u2≤800. The fitted curve of the peak velocity electric field distribution of the waveguide layer over the gradually varying peak velocity electric field can satisfy the Nelder function y 11 =(x1-0.5791) / (-1.09449E-8+0.00795 *(x1-0.5791)+0.00715*(x1-0.5791)^2).

[0094] The fitting curve of the peak rate electric field distribution of the waveguide layer in the SIMS test of the gradually varying peak rate electric field satisfies any one of the Logistic function, Logistic 5 function or Nelder function, forming a high electric field barrier. When electrons are transported from the active region to the p-type layer, they need to overcome the height of the barrier, reducing the reverse leakage rate by 70%~80% and suppressing the reverse leakage of electrons from the active region to the p-type layer. At the same time, the low electric field matches the low-rate transport of holes, avoiding enhanced hole scattering. Meanwhile, the high injection efficiency enables the charge carriers in the active region to quickly reach the stimulated emission threshold, improving the radiative recombination efficiency by 25%~40% and the internal quantum efficiency from 60%~70% to 80%~90%.

[0095] In this embodiment, the fitting curve of the peak velocity electric field distribution of the waveguide layer under the gradually varying peak velocity electric field is shown as follows:

[0096] When the fitted curve of the peak velocity electric field distribution of the waveguide layer under the gradually varying peak velocity electric field satisfies the Logistic function, the Logistic function is y8=f2+(f1-f2) / (1+(x2 / g)^h), where y8 is the peak velocity electric field of the waveguide layer under the gradually varying peak velocity electric field; x2 is the thickness of the waveguide layer under the gradually varying peak velocity electric field; f2 is the saturation limit value; f1 is the initial limit value; g is the threshold characteristic parameter; and h is the transition rate parameter, where: 0.04≤f2≤400000, 0.04≤f1≤400000, 0.002≤g≤200, and 0.001≤h≤100. The fitting curve of the peak velocity electric field distribution of the waveguide layer under the gradually varying peak velocity electric field can satisfy the Logistic function as y8=441.87686+(39.14257-441.87686) / (1+(x2 / 1.74845)^1.22232).

[0097] When the fitted curve of the peak velocity electric field distribution of the waveguide layer under a gradually varying peak velocity electric field satisfies the Logistic5 function, the Logistic5 function is y. 10 =p2+(p1-p2) / (1+(q / x2)^r)^s,y 10 Let be the peak velocity electric field of the waveguide layer under a gradually varying peak velocity electric field; x2 be the thickness of the waveguide layer under the gradually varying peak velocity electric field; p2 be the lower asymptote parameter; p1 be the upper asymptote parameter; q be the midpoint characteristic parameter; r be the rise rate parameter; and s be the saturation shape correction parameter, where: 0.004≤p2≤40000, 0.06≤p1≤6000000, 0.001≤q≤1000, 0.00009≤r≤900, and 0.0001≤s≤10000. The fitted curve of the peak velocity electric field distribution of the waveguide layer under the gradually varying peak velocity electric field can satisfy the Logistic 5 function y 10 =36.93986+(584.86348-36.93986) / (1+(1.70312 / x2)^0.90835)^1.43445.

[0098] When the fitted curve of the peak velocity electric field distribution of the waveguide layer under a gradually varying peak velocity electric field satisfies the Nelder function, the Nelder function is y. 12 =(x2+v) / (w0+w1*(x2+v)+w2*(x2+v)^2),y 12 Let be the peak velocity electric field of the waveguide layer under a gradually varying peak velocity electric field; x2 be the thickness of the waveguide layer under the gradually varying peak velocity electric field; v be the independent variable offset parameter; w0 be the attenuation coefficient in the low independent variable segment; w1 be the linear gain coefficient; and w2 be the attenuation coefficient in the high independent variable segment. Where: -6000 ≤ v ≤ 800, 1E⁻¹⁶ ≤ w0 ≤ 1-E³, 0.000008 ≤ w1 ≤ 800, and -600 ≤ w2 ≤ -0.000006. The fitted curve of the peak velocity electric field distribution of the waveguide layer under the gradually varying peak velocity electric field can satisfy the Nelder function y = 0. 12 =(x2-0.60416) / (1.1816E-8+0.00791*(x2-0.0.79015)+(-0.00684)*(x2-0.0.79015)^2).

[0099] The fitting curve of the peak velocity electric field distribution of the waveguide layer under the gradient peak velocity electric field satisfies any one of the Logistic function, Logistic5 function or Nelder function, so that electrons are always in the transition region between low field and peak field during transport, avoiding premature entry into the high field saturation region, keeping the drift velocity close to the peak saturation electron drift velocity, and improving injection efficiency. At the same time, the smooth gradient electric field distribution eliminates local electric field concentration, reduces field-induced Auger recombination, and reduces the nonradiative recombination rate by 20%~30%. The gradient peak velocity electric field distribution makes the refractive index of the waveguide layer smoothly gradient, eliminates local refractive index abrupt changes, reduces thermal and field-induced refractive index distortion by 70%~80%, and increases the transverse mode jump threshold power by 60%~80%.

[0100] In this embodiment, the fitting curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually varying peak velocity electric field is specifically as follows:

[0101] When the fitted curve of the saturated electron drift velocity distribution of the waveguide layer under a gradually varying peak rate electric field satisfies the Logistic function, the Logistic function is y. 13 =a2'+(a1'-a2') / (1+(x1 / b')^c'),y 13 Let x1 be the saturated electron drift velocity of the waveguide layer under a gradually increasing peak rate electric field; a2' be the saturation limit; a1' be the initial limit; b' be the threshold characteristic parameter, i.e., the core critical value of the transition process; and c' be the transition rate parameter, which determines the steepness and shape factor of the curve, where: 4E3≤a2'≤4E13, 2E3≤a1'≤2E13, 0.0007≤b'≤700, and 0.002≤c'≤200. The fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually increasing peak rate electric field can satisfy the Logistic function y 13 =4.60756E7+(2.76688E7-4.60756E7) / (1+(x1 / 0.70092)^2.62198).

[0102] When the fitted curve of the saturated electron drift velocity distribution in the waveguide layer under a gradually varying peak velocity electric field satisfies the Logistic 5 function, the Logistic 5 function is y. 15 =j2'+(j1'-j2') / (1+(k' / x1)^m')^n', y 15Let be the saturated electron drift velocity of the waveguide layer under the gradient peak rate electric field; x1 be the thickness of the waveguide layer under the gradient peak rate electric field; j2' be the lower asymptote parameter; j1' be the upper asymptote parameter; k' be the midpoint characteristic parameter; m' be the rise rate parameter; and n' be the saturation shape correction parameter, where: 2E3≤j2'≤2E13, 3E3≤j1'≤3E13, 0.0006≤k'≤6000, 0.00001≤m'≤1000, and 0.0001≤n'≤1000. The fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradient peak rate electric field can satisfy the Logistic 5 function y 15 =2.63369E7+(3.71886E7-2.63369E7) / (1+(0.68098 / x1)^11.07916)^0.13933.

[0103] When the fitted curve of the saturated electron drift velocity distribution of the waveguide layer under a gradually varying peak velocity electric field satisfies the Nelder function, which is y 17 =(x1+t') / (u0'+u1'*(x1+t')+u2'*(x1+t')^2), y 17 Let y be the saturated electron drift velocity of the waveguide layer under a gradually increasing peak velocity electric field; x1 be the thickness of the waveguide layer under the gradually increasing peak velocity electric field; t' be the independent variable offset parameter; u0' be the attenuation coefficient in the low independent variable segment; u1' be the linear gain coefficient; and u2' be the attenuation coefficient in the high independent variable segment. Where: -0.00004 ≤ t' ≤ 4000, 5E-16 ≤ u0' ≤ 5E-3, 3E-13 ≤ u1' ≤ 3E-3, -3E-3 ≤ u2' ≤ -3E-13. The fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually increasing peak velocity electric field can satisfy the Nelder function y = 0. 17 =(x1+0.40423) / (5.42722E-9+(3.46149E-8)*(x1+0.40423)+(-1.14474E-8)*(x1+0.40423)^2).

[0104] The fitting curve of the saturated electron drift velocity distribution of the waveguide layer in the SIMS test of the gradually peaked electric field satisfies any one of the Logistic function, Logistic5 function or Nelder function. The saturated electron drift velocity gradually decreases from high to low (from the upper waveguide layer 104 towards the quantum well). The low saturated electron drift velocity on the active region side avoids the punch-through leakage caused by electrons rushing through the active region at high speed, and the carrier leakage rate is reduced by 60%~70%.

[0105] In this embodiment, the fitting curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually varying peak velocity electric field is specifically as follows:

[0106] When the fitted curve of the saturated electron drift velocity distribution in the waveguide layer under a gradually varying peak velocity electric field satisfies the Logistic function, the Logistic function is y. 14 =f2'+(f1'-f2') / (1+(x2 / g')^h'),y 14 Let x1 be the saturated electron drift velocity of the waveguide layer under a gradually increasing peak velocity electric field; x2 be the thickness of the waveguide layer under the gradually increasing peak velocity electric field; f2' be the saturation limit; f1' be the initial limit; g' be the threshold characteristic parameter; and h' be the transition rate parameter, where: -1E13≤f2'≤100, 4E3≤f1'≤4E13, 0.002≤g'≤2000, and 0.001≤h'≤100. The fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually increasing peak velocity electric field satisfies the Logistic function y1. 14 =-1.11991E7+(4.70276E7+1.11991E7) / (1+(x2 / 1.74845)^1.22232).

[0107] When the fitted curve of the saturated electron drift velocity distribution in the waveguide layer under a gradually varying peak velocity electric field satisfies the Logistic 5 function, the Logistic 5 function is y. 16 =p2'+(p1'-p2') / (1+(q' / x2)^r')^s',y 16 Let be the saturated electron drift velocity of the waveguide layer under a gradually increasing peak velocity electric field; x2 be the thickness of the waveguide layer under the gradually increasing peak velocity electric field; p2' be the lower asymptote parameter; p1' be the upper asymptote parameter; q' be the midpoint characteristic parameter; r' be the rise rate parameter; and s' be the saturation shape correction parameter, where: -3E13≤p2'≤300, 4E3≤p1'≤4E13, 0.001≤q'≤1000, -1000≤r'≤100, and 0.0006≤s'≤60000. The fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually increasing peak velocity electric field can satisfy the Logistic 5 function y 16 =-3.28421E7+(4.79708E7+3.28421E7) / (1+(1.78538 / x2)^(-1.11393))^0.69421.

[0108] When the fitted curve of the saturated electron drift velocity distribution in the waveguide layer under a gradually varying peak velocity electric field satisfies the Nelder function, the Nelder function is y. 18 =(x2+v') / (w0'+w1'*(x2+v')+w2'*(x2+v')^2), y 18Let y0 be the saturated electron drift velocity of the waveguide layer under a gradually increasing peak velocity electric field; x2 be the thickness of the waveguide layer under the gradually increasing peak velocity electric field; v' be the independent variable offset parameter; w0 be the attenuation coefficient in the low independent variable segment; w1 be the linear gain coefficient; and w2 be the attenuation coefficient in the high independent variable segment. Where: -8000≤v'≤800, -2E-8≤w0≤-2E-19, 3E-13≤w1≤3E-3, and 1E-16≤w2≤1E-3. The fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually increasing peak velocity electric field satisfies the Nelder function y0. 18 =(x2-0.78978) / ((-1.59793E-14)+(3.21818E-8)*(x2-0.78978)+(1.75773E-8)*(x2-0.78978)^2).

[0109] The fitting curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually changing peak rate electric field satisfies any one of the Logistic function, Logistic5 function or Nelder function. The saturated electron drift velocity gradually changes from high to low (from the lower waveguide layer 102 towards the quantum well). The low saturated electron drift velocity on the active region side avoids the punch-through leakage caused by electrons rushing through the active region at high speed, and the carrier leakage rate is reduced by 60%~70%.

[0110] In some alternative embodiments, the substrate 100 is a GaN single-crystal substrate;

[0111] The lower waveguide layer 102 is any one or any combination of InGaN, GaN / InGaN, GaN / InGaN / GaN, InGaN / GaN, and GaN;

[0112] The active layer 103 is an InGaN / GaN quantum well;

[0113] The upper waveguide layer 104 is any one or any combination of InGaN, GaN / InGaN, GaN / InGaN / GaN, InGaN / GaN, and GaN;

[0114] The electron blocking layer 105 is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0115] The lower confinement layer 101 is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0116] The first upper confinement layer 106a is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0117] The second upper confinement layer 106b is any one or any combination of AlGaN, GaN, InGaN, AlInGaN, and AlN;

[0118] The contact layer 107 is any one or any combination of GaN, AlGaN, InGaN, and AlInGaN.

[0119] In some alternative embodiments, the lower waveguide layer 102 is a combination of GaN and InGaN;

[0120] The upper waveguide layer 104 is an InGaN / GaN combination;

[0121] The upper confinement layer 106 is an AlGaN / AlGaN combination;

[0122] Electron blocking layer 105 is AlGaN;

[0123] The lower confinement layer 101 is an AlGaN / InGaN / AlGaN combination;

[0124] The first upper confinement layer 106a and the upper confinement layer 106 are AlGaN;

[0125] The second upper confinement layer 106b is an AlGaN / GaN combination;

[0126] The contact layer 107 is a GaN / InGaN combination.

[0127] In some alternative embodiments, the thickness of the lower waveguide layer 102 is from 300 angstroms to 8000 angstroms;

[0128] The thickness of the upper waveguide layer 104 is 300 angstroms to 8000 angstroms;

[0129] The thickness of the upper confinement layer 106 is 500 angstroms to 9000 angstroms;

[0130] The thickness of the electron blocking layer 105 ranges from 5 angstroms to 800 angstroms;

[0131] The thickness of the lower confinement layer 101 is 500 angstroms to 80,000 angstroms;

[0132] The thickness of the first upper confinement layer 106a is 100 angstroms to 50,000 angstroms;

[0133] The thickness of the second upper confinement layer 106b is 100 angstroms to 50,000 angstroms;

[0134] The thickness of the contact layer 107 is from 5 angstroms to 500 angstroms.

[0135] The table below compares the performance of the gallium nitride-based semiconductor laser with a graded peak rate electric field waveguide layer proposed in this embodiment with that of a conventional laser. The comparison is mainly based on several aspects, including threshold current, slope efficiency, maximum output power, relaxation oscillation frequency, temperature coefficient of threshold current, slope efficiency at 100℃, slow-axis divergence angle, fast-axis divergence angle, and output lifetime at 50mW room temperature.

[0136] Traditional lasers Laser in this embodiment Performance improvement <![CDATA[Threshold current I th (mA)]]> 60 40-45 Reduced by 20%-35% <![CDATA[Slope efficiency η slope (W / A)]]> 0.5 0.7-0.85 Increase by 30%-50% Maximum output optical power (mW) 150 250-300 Increase by 60%-100% <![CDATA[Relaxation oscillation frequency f R (GHz)]]> 1 2-3 Increase by 2-3 times <![CDATA[Threshold current temperature coefficient T0 (K)]]> 120 180-220 Increase by 50%-80% Slope efficiency at 100℃ (W / A) 0.35 0.6-0.75 Increase by 70%-110% Slow-axis divergence angle (°) 30 24-26 Reduce by 15%-20% Fast axis divergence angle (°) 60 45-48 Reduce by 20%-25% 50mW output lifespan at room temperature (h) <![CDATA[10 4 ]]> <![CDATA[5*10 4 [End]]> Increased by more than 4 times

[0137] As can be seen from the table above, the gallium nitride-based semiconductor laser with a gradient peak rate electric field waveguide layer proposed in this embodiment improves the slope efficiency, maximum output optical power, relaxation oscillation frequency, threshold current temperature coefficient, high-temperature slope efficiency at 100℃, and output lifetime beam quality factor of 50mW at room temperature compared with traditional lasers. It also reduces the threshold current and decreases the slow-axis divergence angle and fast-axis divergence angle, and its performance is significantly better than that of traditional lasers.

[0138] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A gallium nitride-based semiconductor laser with a gradient peak rate electric field waveguide layer, comprising, from bottom to top, a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, a first upper confinement layer, an electron blocking layer, a second upper confinement layer, and a contact layer, characterized in that, The lower waveguide layer includes a first lower waveguide layer and a second lower waveguide layer. The first lower waveguide layer is located below the second lower waveguide layer. The first lower waveguide layer is a constant peak rate electric field lower waveguide layer, and the second lower waveguide layer is a gradually changing peak rate electric field lower waveguide layer. The upper waveguide layer includes a first upper waveguide layer and a second upper waveguide layer. The first upper waveguide layer is located below the second upper waveguide layer. The first upper waveguide layer is a gradually changing peak rate electric field upper waveguide layer, and the second upper waveguide layer is a constant peak rate electric field upper waveguide layer. The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the peak rate electric field distribution, and the fitting curve of the saturated electron drift velocity distribution of the waveguide layer under the gradient peak rate electric field test all satisfy any one of the Logistic function, Logistic5 function, or Nelder function. The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the peak rate electric field distribution, and the fitting curve of the saturated electron drift velocity distribution of the waveguide layer under the SIMS test under the gradually varying peak rate electric field all satisfy any one of the Logistic function, Logistic5 function, or Nelder function.

2. The gallium nitride-based semiconductor laser with a graded peak rate electric field waveguide layer according to claim 1, characterized in that, When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS on the gradient peak rate electric field satisfies the Logistic function, the Logistic function is y1=A2+(A1-A2) / (1+(x1 / B)^C), where y1 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS on the gradient peak rate electric field; x1 is the thickness of the waveguide layer on the gradient peak rate electric field; A2 is the saturation limit value; A1 is the initial limit value; B is the threshold characteristic parameter; and C is the transition rate parameter, where: 1.5E15≤A2≤1.5E26, -3.5E26≤A1≤0, 0.007≤B≤700, and 0.002≤C≤200; When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test under the gradient peak rate electric field satisfies the Logistic function, the Logistic function is y2=F2+(F1-F2) / (1+(x2 / G)^H), where y2 is the In ion intensity or In atom concentration of the waveguide layer under the SIMS test under the gradient peak rate electric field; x2 is the thickness of the waveguide layer under the gradient peak rate electric field; F2 is the saturation limit value; F1 is the initial limit value; G is the threshold characteristic parameter; and H is the transition rate parameter, where: -4.9E26≤F2≤0, 1.8E15≤F1≤1.8E26, 0.002≤G≤200, and 0.002≤H≤200.

3. A gallium nitride-based semiconductor laser having a graded peak- rate electric field waveguide layer as recited in claim 1, wherein, When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS on the gradient peak rate electric field satisfies the Logistic5 function, the Logistic5 function is y3=J2+(J1-J2) / (1+(K / x1)^M)^N, where y3 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS on the gradient peak rate electric field; x1 is the thickness of the waveguide layer on the gradient peak rate electric field; J2 is the lower asymptote parameter; J1 is the upper asymptote parameter; K is the midpoint characteristic parameter; M is the rise rate parameter; and N is the saturation shape correction parameter, where: -4.9E26≤J2≤400, 6.5E15≤J1≤6.5E26, 0.006≤K≤600, 0.01≤M≤10000, and 0.001≤N≤1000. When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test under the gradient peak rate electric field satisfies the Logistic5 function, the Logistic5 function is y4=P2+(P1-P2) / (1+(Q / x2)^R)^S, where y4 is the In ion intensity or In atom concentration of the waveguide layer under the SIMS test under the gradient peak rate electric field; x2 is the thickness of the waveguide layer under the gradient peak rate electric field; P2 is the lower asymptote parameter; P1 is the upper asymptote parameter; Q is the midpoint characteristic parameter; R is the rise rate parameter; and S is the saturation shape correction parameter, where: -7E26≤P2≤700, 2E15≤P1≤2E26, 0.001≤Q≤100, -10000≤R≤100, and 0.0006≤S≤6000.

4. The gallium nitride-based semiconductor laser with a graded peak rate electric field waveguide layer according to claim 1, characterized in that, When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer measured by SIMS on the gradient peak rate electric field satisfies the Nelder function, the Nelder function is y5=(x1+T) / (U0+U1*(x1+T)+U2*(x1+T)^2), where y5 is the In ion intensity or In atom concentration of the waveguide layer measured by SIMS on the gradient peak rate electric field; x1 is the thickness of the waveguide layer on the gradient peak rate electric field; T is the independent variable offset parameter; U0 is the attenuation coefficient of the low independent variable segment; U1 is the linear gain coefficient; and U2 is the attenuation coefficient of the high independent variable segment. Wherein: -4000≤T≤400, 5E-28≤U0≤5E-17, -4E-22≤U1≤400, 1E-27≤U2≤1E-16. When the fitting curve of the In ion intensity distribution or In atom concentration distribution of the waveguide layer under the SIMS test under the gradient peak rate electric field satisfies the Nelder function, the Nelder function is y6=(x2+V) / (W0+W1*(x2+V)+W2*(x2+V)^2), where y6 is the In ion intensity or In atom concentration of the waveguide layer under the SIMS test under the gradient peak rate electric field; x2 is the thickness of the waveguide layer under the gradient peak rate electric field; V is the independent variable offset parameter; W0 is the attenuation coefficient of the low independent variable segment; W1 is the linear gain coefficient; and W2 is the attenuation coefficient of the high independent variable segment; wherein: -8000≤V≤800, -4E-17≤W0≤400, 5E-27≤W1≤5E-17, and 2E-26≤W2≤2E-16.

5. The gallium nitride-based semiconductor laser with a graded peak rate electric field waveguide layer according to claim 1, characterized in that, When the fitting curve of the peak velocity electric field distribution of the waveguide layer on the gradient peak velocity electric field satisfies the Logistic function, the Logistic function is y7=a2+(a1-a2) / (1+(x1 / b)^c), where y7 is the peak velocity electric field of the waveguide layer on the gradient peak velocity electric field; x1 is the thickness of the waveguide layer on the gradient peak velocity electric field; a2 is the saturation limit value; a1 is the initial limit value; b is the threshold characteristic parameter; and c is the transition rate parameter, where: 0.05≤a2≤50000, 0.01≤a1≤100000, 0.0007≤b≤700, and 0.002≤c≤200; When the fitted curve of the peak rate electric field distribution of the waveguide layer under the gradient peak rate electric field satisfies the Logistic function, the Logistic function is y8=f2+(f1-f2) / (1+(x2 / g)^h), where y8 is the peak rate electric field of the waveguide layer under the gradient peak rate electric field; x2 is the thickness of the waveguide layer under the gradient peak rate electric field; f2 is the saturation limit value; f1 is the initial limit value; g is the threshold characteristic parameter; and h is the transition rate parameter, where: 0.04≤f2≤400000, 0.04≤f1≤400000, 0.002≤g≤200, and 0.001≤h≤100.

6. The gallium nitride-based semiconductor laser with a graded peak rate electric field waveguide layer according to claim 1, characterized in that, When the fitting curve of the peak velocity electric field distribution of the waveguide layer on the gradient peak velocity electric field satisfies the Logistic5 function, the Logistic5 function is y9=j2+(j1-j2) / (1+(k / x1)^m)^n, where y9 is the peak velocity electric field of the waveguide layer on the gradient peak velocity electric field; x1 is the thickness of the waveguide layer on the gradient peak velocity electric field; j2 is the lower asymptote parameter; j1 is the upper asymptote parameter; k is the midpoint characteristic parameter; m is the rise rate parameter; and n is the saturation shape correction parameter, where: 0.02≤j2≤2000000, 0.006≤j1≤60000, 0.00086≤k≤8000, -20000≤m≤200, and 0.002≤n≤20000. When the fitted curve of the peak velocity electric field distribution of the waveguide layer under the gradually varying peak velocity electric field satisfies the Logistic5 function, the Logistic5 function is y 10 =p2+(p1-p2) / (1+(q / x2)^r)^s,y 10 denoted as q, where q is the peak velocity electric field of the waveguide layer under a gradient peak velocity electric field; x2 is the thickness of the waveguide layer under a gradient peak velocity electric field; p2 is the lower asymptote parameter; p1 is the upper asymptote parameter; q is the midpoint characteristic parameter; r is the rise rate parameter; and s is the saturation shape correction parameter. Where: 0.004≤p2≤40000, 0.06≤p1≤6000000, 0.001≤q≤1000, 0.00009≤r≤900, and 0.0001≤s≤10000.

7. The gallium nitride-based semiconductor laser with a graded peak rate electric field waveguide layer according to claim 1, characterized in that, When the fitted curve of the peak velocity electric field distribution of the waveguide layer on the gradually varying peak velocity electric field satisfies the Nelder function, the Nelder function is y 11 =(x1+t) / (u0+u1*(x1+t)+u2*(x1+t)^2),y 11 The peak velocity electric field of the waveguide layer is the gradually varying peak velocity electric field. x1 is the thickness of the waveguide layer under the gradually varying peak velocity electric field, t is the independent variable offset parameter, u0 is the attenuation coefficient in the low independent variable segment, u1 is the linear gain coefficient, and u2 is the attenuation coefficient in the high independent variable segment; where: -5000≤t≤500, -1E-3≤u0≤-1E-13, 0.000008≤u1≤800, 0.000008≤u2≤800; When the fitted curve of the peak velocity electric field distribution of the waveguide layer under the gradually varying peak velocity electric field satisfies the Nelder function, the Nelder function is y 12 =(x2+v) / (w0+w1*(x2+v)+w2*(x2+v)^2),y 12 denoted as , where is the peak velocity electric field of the waveguide layer under a gradually varying peak velocity electric field; x2 is the thickness of the waveguide layer under the gradually varying peak velocity electric field; v is the independent variable offset parameter; w0 is the attenuation coefficient in the low independent variable segment; w1 is the linear gain coefficient; and w2 is the attenuation coefficient in the high independent variable segment. Where: -6000≤v≤800, 1E-16≤w0≤1-E3, 0.000008≤w1≤800, -600≤w2≤-0.000006.

8. The gallium nitride-based semiconductor laser with a graded peak rate electric field waveguide layer according to claim 1, characterized in that, When the fitted curve of the saturated electron drift velocity distribution of the waveguide layer on the gradually varying peak rate electric field satisfies the Logistic function, the Logistic function is y 13 =a2'+(a1'-a2') / (1+(x1 / b')^c'),y 13 denoted as saturated electron drift velocity of the waveguide layer under a gradually increasing peak rate electric field; x1 is the thickness of the waveguide layer under the gradually increasing peak rate electric field; a2' is the saturation limit; a1' is the initial limit; b' is the threshold characteristic parameter, i.e., the core critical value of the transition process; and c' is the transition rate parameter that determines the steepness and shape factor of the curve, where: 4E3≤a2'≤4E13, 2E3≤a1'≤2E13, 0.0007≤b'≤700, and 0.002≤c'≤200. When the fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually varying peak rate electric field satisfies the Logistic function, the Logistic function is y 14 =f2'+(f1'-f2') / (1+(x2 / g')^h'),y 14 denoted as saturated electron drift velocity of the waveguide layer under a gradually varying peak rate electric field; x2 is the thickness of the waveguide layer under a gradually varying peak rate electric field; f2' is the saturation limit; f1' is the initial limit; g' is the threshold characteristic parameter; and h' is the transition rate parameter, where: -1E13≤f2'≤100, 4E3≤f1'≤4E13, 0.002≤g'≤2000, and 0.001≤h'≤100.

9. The gallium nitride-based semiconductor laser with a graded peak rate electric field waveguide layer according to claim 1, characterized in that, When the fitted curve of the saturated electron drift velocity distribution of the waveguide layer on the gradually varying peak rate electric field satisfies the Logistic 5 function, the Logistic 5 function is y 15 =j2'+(j1'-j2') / (1+(k' / x1)^m')^n', y 15 denoted as , where is the saturated electron drift velocity of the waveguide layer under the gradient peak velocity electric field; x1 is the thickness of the waveguide layer under the gradient peak velocity electric field; j2' is the lower asymptote parameter; j1' is the upper asymptote parameter; k' is the midpoint characteristic parameter; m' is the rise rate parameter; and n' is the saturation shape correction parameter, where: 2E3≤j2'≤2E13, 3E3≤j1'≤3E13, 0.0006≤k'≤6000, 0.00001≤m'≤1000, and 0.0001≤n'≤1000. When the fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually varying peak rate electric field satisfies the Logistic 5 function, the Logistic 5 function is y 16 =p2'+(p1'-p2') / (1+(q' / x2)^r')^s',y 16 q' is the saturated electron drift velocity of the waveguide layer under a gradient peak rate electric field; x2 is the thickness of the waveguide layer under a gradient peak rate electric field; p2' is the lower asymptote parameter; p1' is the upper asymptote parameter; q' is the midpoint characteristic parameter; r' is the rise rate parameter; and s' is the saturation shape correction parameter, where: -3E13≤p2'≤300, 4E3≤p1'≤4E13, 0.001≤q'≤1000, -1000≤r'≤100, and 0.0006≤s'≤60000.

10. A gallium nitride based semiconductor laser having a graded peak velocity electric field waveguide layer as claimed in claim 1, wherein, When the fitted curve of the saturated electron drift velocity distribution of the waveguide layer on the gradually varying peak rate electric field satisfies the Nelder function, the Nelder function is y 17 =(x1+t') / (u0'+u1'*(x1+t')+u2'*(x1+t')^2), y 17 denoted as saturated electron drift velocity of the waveguide layer under a gradually increasing peak velocity electric field; x1 is the thickness of the waveguide layer under the gradually increasing peak velocity electric field; t' is the independent variable offset parameter; u0' is the attenuation coefficient in the low independent variable segment; u1' is the linear gain coefficient; u2' is the attenuation coefficient in the high independent variable segment; where: -0.00004≤t'≤4000, 5E-16≤u0'≤5E-3, 3E-13≤u1'≤3E-3, -3E-3≤u2'≤-3E-13; When the fitted curve of the saturated electron drift velocity distribution of the waveguide layer under the gradually varying peak rate electric field satisfies the Nelder function, the Nelder function is y 18 =(x2+v') / (w0'+w1'*(x2+v')+w2'*(x2+v')^2), y 18 denoted as saturated electron drift velocity of the waveguide layer under a gradually increasing peak velocity electric field; x2 is the thickness of the waveguide layer under a gradually increasing peak velocity electric field; v' is the independent variable offset parameter; w0' is the attenuation coefficient in the low independent variable segment; w1' is the linear gain coefficient; w2' is the attenuation coefficient in the high independent variable segment; where: -8000≤v'≤800, -2E-8≤w0'≤-2E-19, 3E-13≤w1'≤3E-3, 1E-16≤w2'≤1E-3.

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