Group III nitride semiconductor laser epitaxial structure

Abstract

The invention provides a group III nitride semiconductor laser epitaxial structure which comprises a substrate, a lower limiting layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper limiting layer which are sequentially arranged from bottom to top, and a Bessel beam modulation layer is arranged between the active layer and the upper waveguide layer. The Bessel beam modulation layer has an electron affinity distribution characteristic and a piezoelectric polarization coefficient distribution characteristic, the electron affinity of the Bessel beam modulation layer has a function y1 = ax < 3 > + bx < 2 > + cx + d curve distribution, a is greater than 0, 4 (b2-3ac) is less than 0, and the piezoelectric polarization coefficient of the Bessel beam modulation layer has a function y2 = J + x < 2 > + Kex curve distribution. According to the invention, the epitaxial structure performance of the III-group nitride semiconductor laser can be improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor optoelectronic devices, and in particular to a III-nitride semiconductor laser epitaxial structure. 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:

[0009] 1) The optical waveguide has high absorption loss. Intrinsic carbon impurities in p-type semiconductors will compensate for acceptors and destroy p-type. The ionization rate of p-type doping is low. A large amount of unionized Mg acceptor impurities will lead to increased internal optical losses. In addition, the refractive index of the laser is dispersed. The high-concentration carrier concentration fluctuation affects the refractive index of the active layer. The confinement factor decreases with increasing wavelength, resulting in a decrease in the mode gain of the laser.

[0010] 2) The laser light wave can be divided into transverse mode and longitudinal mode. The transverse mode intensity distribution in the cross section perpendicular to the optical axis is determined by the waveguide structure of the semiconductor laser. If the transverse mode is complex and unstable, the coherence of the output light is poor. The longitudinal mode is a standing wave distribution in the propagation direction of the resonant cavity. If many longitudinal modes are simultaneously emitted or there are inter-mode changes, high temporal coherence cannot be obtained, and the far-field image FFP quality is poor.

[0011] 3) After the laser is lased, the carrier concentration in the multi-quantum well active region is saturated, the bipolar conductivity effect is weakened, and the series resistance of the laser increases, causing the laser voltage to rise. Summary of the invention

[0012] To solve one of the above technical problems, the present invention provides a III-nitride semiconductor laser epitaxial structure.

[0013] An embodiment of the present invention provides a III-nitride semiconductor laser epitaxial structure, comprising a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper confinement layer arranged in sequence from bottom to top, wherein a Bessel beam modulation layer is arranged between the active layer and the upper waveguide layer, wherein the Bessel beam modulation layer has an electron affinity distribution characteristic and a piezoelectric polarization coefficient distribution characteristic, and wherein the electron affinity of the Bessel beam modulation layer has a function y1=ax 3 +bx 2 +cx+d curve distribution, and a>0, △=4(b 2 -3ac)<0, the piezoelectric polarization coefficient of the Bessel beam modulation layer has the function y2=J+x 2 +Ke x Curve distribution, x is the depth from the Bessel beam modulation layer to the upper waveguide layer.

[0014] Preferably, the Bessel beam modulation layer also has a lattice constant distribution characteristic, and the lattice constant of the Bessel beam modulation layer has a function y3=ex 3 +fx 2 +gx+h curve distribution, and e>0, △=4(f 2 -3eg)<0.

[0015] Preferably, the Bessel beam modulation layer also has a breakdown field intensity distribution characteristic, and the breakdown field intensity of the Bessel beam modulation layer has a function y4=ix 3+jx 2 +kx+l curve distribution, and i>0, △=4(j 2 -3ik)<0,l≥h≥d≥J.

[0016] Preferably, the active layer and the upper waveguide layer both have electron affinity distribution characteristics, piezoelectric polarization coefficient distribution characteristics, lattice constant distribution characteristics and breakdown field strength distribution characteristics;

[0017] The electron affinity of the active layer is greater than or equal to the electron affinity of the Bessel beam modulation layer and greater than or equal to the electron affinity of the upper waveguide layer;

[0018] The piezoelectric polarization coefficient of the active layer is greater than or equal to the piezoelectric polarization coefficient of the Bessel beam modulation layer and greater than or equal to the piezoelectric polarization coefficient of the upper waveguide layer;

[0019] The lattice constant of the active layer is greater than or equal to the lattice constant of the Bessel beam modulation layer and greater than or equal to the lattice constant of the upper waveguide layer;

[0020] The breakdown field strength of the active layer ≥ the breakdown field strength of the Bessel beam modulation layer ≥ the breakdown field strength of the upper waveguide layer.

[0021] Preferably, the Bessel beam modulation layer further has an In / H element ratio distribution characteristic, an In / C element ratio distribution characteristic and an In / O element ratio distribution characteristic;

[0022] The In / H element ratio of the Bessel beam modulation layer has a function y5=mx 3 +nx 2 +px+q curve distribution, and m>0, △=4(n 2 -3mp)<0;

[0023] The In / C element ratio of the Bessel beam modulation layer has a function y6=Ax 3 +Bx 2 +Cx+D curve distribution, and A>0, △=4(B 2 -3AC)<0;

[0024] The In / O element ratio of the Bessel beam modulation layer has a function y7=Ex 3 +Fx 2 +Gx+H curve distribution, and E>0, △=4(F 2 -3EG)<0;

[0025] Among them, D≥H≥q.

[0026] Preferably, the Bessel beam modulation 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, and BN.

[0027] Preferably, the active layer is a periodic structure consisting of a well layer and a barrier layer, the number of periods is 3≥m≥1, the well layer is any one or any combination of InGaN, InN, AlInN, GaN, and has a thickness of 10 to 100 angstroms, and the barrier layer is any one or any combination of GaN, AlGaN, AlInGaN, AlN, AlInN, and has a thickness of 10 to 200 angstroms.

[0028] Preferably, the lower limiting layer, the lower waveguide layer, the upper waveguide 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, and BN.

[0029] Preferably, the substrate comprises sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, sapphire / SiN x , Sapphire / SiO2 / SiN x Any one of a composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0030] The beneficial effects of the present invention are as follows: the present invention arranges a Bessel beam modulation layer between the active layer and the upper waveguide layer of the III-nitride semiconductor laser epitaxial structure, and designs specific electron affinity energy distribution characteristics and piezoelectric polarization coefficient distribution characteristics in the Bessel beam modulation layer, so that the Bessel beam modulation layer has a single-layer moiré metasurface or a multi-layer moiré metasurface cascade, constructs a resonant plasmon metasurface, continuously generates terahertz Bessel beams of different orders, manipulates the orbital angular momentum and topological charge of the Bessel beam, and enhances nonlinear light at a subwavelength scale. In science, the laser is modulated in a specific phase and diffraction-free distance, the third harmonic is enhanced, the spatiotemporal coherence of the laser is improved, the mode fluctuation and multi-mode of the laser are reduced, the focusing resolution size of the laser is reduced, and the far-field image FFP quality and beam quality factor are improved; at the same time, the Bessel beam modulation layer induces the generation of Stokes light of opposite topological order and spin order and amplifies the pump laser, and the periodic vortex topological array generates several focused vortex lights with equal energy and different topological charges in the longitudinal direction, which enhances laser oscillation and increases the light transmission distance, thereby improving the laser power and quantum efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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:

[0032] Figure 1 It is a schematic structural diagram of the epitaxial structure of the III-nitride semiconductor laser according to an embodiment of the present invention.

[0033] Reference numerals:

[0034] 100. substrate, 101. lower confinement layer, 102. lower waveguide layer, 103. active layer, 104. upper waveguide layer, 105. upper confinement layer, 106. Bessel beam modulation layer. DETAILED DESCRIPTION

[0035] 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.

[0036] like Figure 1As shown, this embodiment proposes a III-nitride semiconductor laser epitaxial structure, including a substrate 100, a lower confinement layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104 and an upper confinement layer 105 arranged in sequence from bottom to top, and a Bessel beam modulation layer 106 is also arranged in the III-nitride semiconductor laser epitaxial structure.

[0037] Specifically, in this embodiment, the III-nitride semiconductor laser epitaxial structure 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 and an upper confinement layer 105 in order from bottom to top. A Bessel beam modulation layer 106 is also provided in the semiconductor laser element. The Bessel beam modulation layer 106 is provided between the active layer 103 and the upper waveguide layer 104. In the Bessel beam modulation layer 106, there are specific electron affinity distribution characteristics and piezoelectric polarization coefficient distribution characteristics, which are specifically manifested as follows:

[0038] The electron affinity of the Bessel beam modulation layer 106 has the function y1=ax 3 +bx 2 +cx+d curve distribution, and a>0, △=4(b 2 -3ac)<0;

[0039] The piezoelectric polarization coefficient of the Bessel beam modulation layer 106 has the function y2=J+x 2 +Ke x Curve distribution;

[0040] Here, x is the depth of the Bessel beam modulation layer 106 toward the upper waveguide layer 104 .

[0041] In this embodiment, a Bessel beam modulation layer 106 is arranged between the active layer 103 and the upper waveguide layer 104 of the III-nitride semiconductor laser epitaxial structure, and specific electron affinity distribution characteristics and piezoelectric polarization coefficient distribution characteristics are designed in the Bessel beam modulation layer 106, so that the Bessel beam modulation layer 106 has a single-layer moiré metasurface or a multi-layer moiré metasurface cascade, a resonant plasmon metasurface is constructed, terahertz Bessel beams of different orders are continuously generated, the orbital angular momentum and topological charge of the Bessel beam are manipulated, and nonlinear enhancement is enhanced on a subwavelength scale. The Bessel beam modulation layer induces Stokes light of opposite topological order and spin order to generate and amplify the pump laser, and the periodic vortex topological array generates several focused vortex lights with equal energy and different topological charges in the longitudinal direction, which enhances laser oscillation and increases light transmission distance, thereby improving laser power and quantum efficiency.

[0042] In some optional embodiments, the Bessel beam modulation layer 106 also has a lattice constant distribution characteristic. Specifically, the lattice constant of the Bessel beam modulation layer 106 has a function y3=ex 3 +fx 2 +gx+h curve distribution, and e>0, △=4(f 2 -3eg)<0.

[0043] In some optional embodiments, the Bessel beam modulation layer 106 also has a breakdown field intensity distribution characteristic. Specifically, the breakdown field intensity of the Bessel beam modulation layer 106 has a function y4=ix 3 +jx 2 +kx+l curve distribution, and i>0, △=4(j 2 -3ik)<0,l≥h≥d≥J.

[0044] In some optional embodiments, the active layer 103 and the upper waveguide layer 104 both have electron affinity distribution characteristics, piezoelectric polarization coefficient distribution characteristics, lattice constant distribution characteristics and breakdown field strength distribution characteristics, and the electron affinity, piezoelectric polarization coefficient, lattice constant and breakdown field strength in the active layer 103, the Bessel beam modulation layer 106 and the upper waveguide layer 104 also have a certain relationship, which is specifically shown as follows:

[0045] The electron affinity of the active layer 103 is greater than or equal to the electron affinity of the Bessel beam modulation layer 106 and greater than or equal to the electron affinity of the upper waveguide layer 104;

[0046] The piezoelectric polarization coefficient of the active layer 103 ≥ the piezoelectric polarization coefficient of the Bessel beam modulation layer 106 ≥ the piezoelectric polarization coefficient of the upper waveguide layer 104;

[0047] The lattice constant of the active layer 103 ≥ the lattice constant of the Bessel beam modulation layer 106 ≥ the lattice constant of the upper waveguide layer 104;

[0048] The breakdown field strength of the active layer 103 ≥ the breakdown field strength of the Bessel beam modulation layer 106 ≥ the breakdown field strength of the upper waveguide layer 104 .

[0049] In some optional embodiments, the Bessel beam modulation layer 106 further has an In / H element ratio distribution characteristic, an In / C element ratio distribution characteristic, and an In / O element ratio distribution characteristic.

[0050] Specifically, the In / H element ratio of the Bessel beam modulation layer 106 has a function y5=mx 3 +nx 2 +px+q curve distribution, and m>0, △=4(n 2 -3mp)<0;

[0051] The In / C element ratio of the Bessel beam modulation layer 106 has a function y6=Ax 3 +Bx 2 +Cx+D curve distribution, and A>0, △=4(B 2 -3AC)<0;

[0052] The In / O element ratio of the Bessel beam modulation layer 106 has a function y7=Ex 3 +Fx 2 +Gx+H curve distribution, and E>0, △=4(F 2 -3EG)<0;

[0053] Among them, D≥H≥q.

[0054] The In / H element ratio, In / C element ratio and In / O element ratio of the Bessel beam modulation layer 106 all have the function y5=mx 3 +nx 2 +px+q curve distribution, and m>0, △=4(n 2 -3mp)<0.

[0055] In some optional embodiments, the Bessel beam modulation layer 106 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, and BN.

[0056] 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, the well layer is any one or any combination of InGaN, InN, AlInN, GaN, and has a thickness of 10 to 100 angstroms, and the barrier layer is any one or any combination of GaN, AlGaN, AlInGaN, AlN, AlInN, and has a thickness of 10 to 200 angstroms.

[0057] In some optional embodiments, the lower confinement layer 101, the lower waveguide layer 102, the upper waveguide layer 104 and the upper confinement layer 105 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, and BN.

[0058] In some optional embodiments, the substrate 100 includes sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, sapphire / SiN x , Sapphire / SiO2 / SiN x Any one of a composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0059] The following table is a parameter comparison between a conventional semiconductor laser element and the III-nitride semiconductor laser epitaxial structure proposed in this embodiment, including beam quality factor, slope efficiency, threshold current density, optical power, and external quantum efficiency, showing the difference between the conventional semiconductor laser element and the III-nitride semiconductor laser epitaxial structure proposed in this embodiment:

[0060]

[0061] It can be seen that the III-nitride semiconductor laser epitaxial structure proposed in this embodiment improves the beam quality factor, slope efficiency, optical power and external quantum efficiency, and reduces the threshold current density compared with traditional semiconductor laser elements, and has obvious advantages over traditional semiconductor laser elements.

[0062] 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. A III-nitride semiconductor laser epitaxial structure, comprising a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper confinement layer arranged in sequence from bottom to top, characterized in that: A Bessel beam modulation layer is arranged between the active layer and the upper waveguide layer. The Bessel beam modulation layer has electron affinity distribution characteristics and piezoelectric polarization coefficient distribution characteristics. The electron affinity of the Bessel beam modulation layer has a function y1=ax 3 +bx 2 +cx+d curve distribution, and a>0, △=4(b 2 -3ac)<0, the piezoelectric polarization coefficient of the Bessel beam modulation layer has the function y2=J+x 2 +Ke x Curve distribution, x is the depth from the Bessel beam modulation layer to the upper waveguide layer.

2. The III-nitride semiconductor laser epitaxial structure according to claim 1, characterized in that: The Bessel beam modulation layer also has a lattice constant distribution characteristic. The lattice constant of the Bessel beam modulation layer has a function y3=ex 3 +fx 2 +gx+h curve distribution, and e>0, △=4(f 2 -3eg)<0.

3. The III-nitride semiconductor laser epitaxial structure according to claim 2, characterized in that: The Bessel beam modulation layer also has a breakdown field intensity distribution characteristic. The breakdown field intensity of the Bessel beam modulation layer has a function y4=ix 3 +jx 2 +kx+l curve distribution, and i>0, △=4(j 2 -3ik)<0,l≥h≥d≥J.

4. The III-nitride semiconductor laser epitaxial structure according to claim 3, characterized in that: The active layer and the upper waveguide layer both have electron affinity distribution characteristics, piezoelectric polarization coefficient distribution characteristics, lattice constant distribution characteristics and breakdown field strength distribution characteristics; The electron affinity of the active layer is greater than or equal to the electron affinity of the Bessel beam modulation layer and greater than or equal to the electron affinity of the upper waveguide layer; The piezoelectric polarization coefficient of the active layer is greater than or equal to the piezoelectric polarization coefficient of the Bessel beam modulation layer and greater than or equal to the piezoelectric polarization coefficient of the upper waveguide layer; The lattice constant of the active layer is greater than or equal to the lattice constant of the Bessel beam modulation layer and greater than or equal to the lattice constant of the upper waveguide layer; The breakdown field strength of the active layer ≥ the breakdown field strength of the Bessel beam modulation layer ≥ the breakdown field strength of the upper waveguide layer.

5. The III-nitride semiconductor laser epitaxial structure according to claim 1, wherein: The Bessel beam modulation layer also has an In / H element ratio distribution characteristic, an In / C element ratio distribution characteristic and an In / O element ratio distribution characteristic; The In / H element ratio of the Bessel beam modulation layer has a function y5=mx 3 +nx 2 +px+q curve distribution, and m>0, △=4(n 2 -3mp)<0; The In / C element ratio of the Bessel beam modulation layer has a function y6=Ax 3 +Bx 2 +Cx+D curve distribution, and A>0, △=4(B 2 -3AC)<0; The In / O element ratio of the Bessel beam modulation layer has a function y7=Ex 3 +Fx 2 +Gx+H curve distribution, and E>0, △=4(F 2 -3EG)<0; Among them, D≥H≥q.

6. The III-nitride semiconductor laser epitaxial structure according to claim 1, wherein: The Bessel beam modulation 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, and BN.

7. The III-nitride semiconductor laser epitaxial structure according to claim 1, wherein: The active layer is a periodic structure composed of a well layer and a barrier layer, the number of periods is 3≥m≥1, the well layer is any one or any combination of InGaN, InN, AlInN, GaN, and has a thickness of 10 to 100 angstroms, and the barrier layer is any one or any combination of GaN, AlGaN, AlInGaN, AlN, and AlInN, and has a thickness of 10 to 200 angstroms.

8. The III-nitride semiconductor laser epitaxial structure according to claim 1, wherein: The lower limiting layer, lower waveguide layer, upper waveguide layer and 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, and BN.

9. The III-nitride semiconductor laser epitaxial structure according to claim 1, wherein: The substrate includes sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, sapphire / SiN x , Sapphire / SiO2 / SiN x Any one of a composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

Images