A gallium nitride-based semiconductor laser element

Abstract

The application discloses a gallium nitride-based semiconductor laser element, which comprises, from bottom to top, a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper confinement layer, and a polariton lattice layer is arranged between the upper waveguide layer and the upper confinement layer. The polariton lattice layer has a broken space inversion symmetry, forms a three-dimensional topological monopole, controls anisotropic polariton propagation, embeds a vector between an electron hole containing band on a Fermi surface, improves a motion rate of the polariton, induces asymmetric barriers at the top and the bottom of the active layer, improves a tunneling probability of a carrier, enhances a laser confinement factor and optical power, reduces dynamic conductivity caused by band transition, improves transport and injection uniformity of a hole in the active layer, suppresses generation of a non-radiative charged exciton and Auger recombination of an exciton-charge, enhances cascade conversion and spin-orbit coupling between energy bands, reduces a lasing threshold by increasing a high-energy level exciton occupation number inversion.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic device technology, and more particularly to a gallium nitride-based semiconductor laser element. 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 differ significantly from nitride semiconductor light-emitting diodes.

[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 spontaneously emitted, and the output power of a single light-emitting diode is in the mW range.

[0005] 2) The operating current density of the laser reaches KA / cm². 2 The efficiency is more than two orders of magnitude higher than that of nitride light-emitting diodes, resulting 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 quantum wells or pn junctions under the action of external voltage, generating radiative recombination. Lasers, on the other hand, 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:

[0009] 1. Increased In content in the quantum well leads to In content fluctuations and strain, resulting in a broadened laser gain spectrum and a decrease in peak gain. Increased In content in the quantum well also deteriorates thermal stability. High-temperature p-type semiconductor and confinement layer growth can cause thermal degradation of the active layer, reducing the quality of the active layer and the interface quality. High defect density inside the active layer, large inter-solution gap between InN and GaN, InN phase segregation, thermal degradation, and imperfect crystal quality all contribute to imperfect quantum well quality and interface quality, increasing the number of non-radiative recombination centers.

[0010] 2. p-type semiconductors have high Mg acceptor activation energy and low ionization efficiency. The hole concentration is much lower than the electron concentration and the hole mobility is much lower than the electron mobility. In addition, the quantum well polarization electric field raises the hole injection barrier and causes hole overflow from the active layer. Hole injection is uneven and inefficient, resulting in severe electron-hole asymmetry and mismatch in the quantum well. Electron leakage and carrier delocalization make hole transport in the quantum well more difficult, and the carrier injection is uneven. This leads to uneven gain, and at the same time, the laser gain spectrum becomes wider and the peak gain decreases, resulting in an increase in the laser threshold current and a decrease in slope efficiency.

[0011] 3. Increasing the thickness of the lower confinement layer can reduce the refractive index of the confinement layer, but increasing the thickness of the lower confinement layer will also limit the range of composition control, and easily cause problems such as cracking, bending and quality degradation. At the same time, the light field has dissipation, and the light field mode leakage to the substrate to form standing waves will lead to low substrate mode suppression efficiency and poor far-field image FFP quality. Summary of the Invention

[0012] This invention proposes a gallium nitride-based semiconductor laser element that modulates atomic polarization to give atoms electric dipole moments, forming an ordered lattice layer of interacting electric dipole moments, tuning the rotational arrangement of the lattice, suppressing nonradiative recombination, and improving the lasing power and slope efficiency of the laser element.

[0013] The present invention provides a gallium nitride-based semiconductor laser device, which includes, from bottom to top, a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper confinement layer, wherein a polarized exciton lattice layer is provided between the upper waveguide layer and the upper confinement layer.

[0014] Preferably, the polarized exciton lattice 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.

[0015] Preferably, the electron mobility distribution of the polarized exciton lattice layer has a function y = A + B * tanx curve distribution.

[0016] Preferably, the thermal conductivity distribution of the polarized exciton lattice layer has a function y = C + D * cotx curve distribution.

[0017] Preferably, the bandgap distribution of the polarized exciton lattice layer has a function y = ax 3 +bx 2 +cx+d(a<0,△=4(b 2 -3ac)<0) curve distribution.

[0018] Preferably, the dielectric constant distribution of the polarized exciton lattice layer has a function y = e^x. 3 +fx 2 +gx+h(e>0,△=4(f 2 -3eg)<0 curve distribution.

[0019] Preferably, the Al / C element ratio distribution of the polarized exciton lattice layer has a fourth quadrant curve distribution of the function y = E + F*x / lnx.

[0020] Preferably, the active layer is a periodic structure composed of a well layer and a barrier layer, with a period number of 3 ≥ m ≥ 1. The well layer is any one 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. Any combination, with a thickness of 10–100 angstroms, and the barrier layer being 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, with a thickness of 10–200 angstroms.

[0021] Preferably, the lower confinement layer, lower waveguide layer, upper waveguide layer, and upper confinement layer are any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, and BN.

[0022] Preferably, the substrate comprises sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, sapphire / SiNx, sapphire / SiO2 / SiN x The composite substrate, or any one of the following: magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2, and LiGaO2 composite substrate.

[0023] Compared to existing technologies, the gallium nitride-based semiconductor laser element provided in this invention offers the following advantages: The polarized exciton lattice layer exhibits spatial inversion symmetry breaking, forming three-dimensional topological monopoles. This controls the propagation of anisotropic polarons, resulting in interband nesting vectors in electron-hole pairs on the Fermi surface. This enhances the polarized exciton velocity, induces asymmetric barriers at the top and bottom of the active layer, increases carrier tunneling probability, and improves the laser's confinement factor and optical power. Furthermore, it reduces the dynamic conductivity caused by interband transitions, improves the uniformity of hole transport and injection in the active layer, suppresses the generation of nonradiative charged excitons and Auger recombination of excitons and charges, enhances the laser's confinement factor and optical power, strengthens interband cascade conversion and spin-orbit coupling, enhances high-level exciton occupancy inversion, and lowers the lasing threshold. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a gallium nitride-based semiconductor laser element provided by the present invention.

[0025] Figure 2 The present invention provides a SIMS secondary ion mass spectrum of a gallium nitride-based semiconductor laser device.

[0026] The diagram shows: 100: substrate; 101: lower confinement layer; 102: lower waveguide layer; 103: active layer; 104: upper waveguide layer; 105: upper confinement layer; 106: polarized exciton lattice layer. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] To address the aforementioned issues, a gallium nitride-based semiconductor laser element provided in this application will be described in detail and explained through the following specific embodiments.

[0029] Reference Figure 1-2 The present invention provides a gallium nitride-based semiconductor laser device, comprising, from bottom to top, 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. A polarized exciton lattice layer 106 is disposed between the upper waveguide layer 104 and the upper confinement layer 105. The polarized exciton lattice 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, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, and BN.

[0030] In this invention, the electron mobility distribution of the polarized exciton lattice layer 106 exhibits a function y = A + B * tanx curve distribution. By regulating atomic polarization, atoms acquire electric dipole moments, forming an ordered lattice layer with interacting electric dipole moments. This tunes the rotational arrangement of the lattice, suppresses nonradiative recombination, and improves the lasing power and slope efficiency of the laser element.

[0031] In this invention, the thermal conductivity distribution of the polarized exciton lattice layer 106 exhibits a function y = C + D * cotx curve distribution. This controls exciton transport and exciton condensation generated by the excitation of atoms in the active layer lattice, suppresses In composition fluctuations and strain in the active layer, enhances peak gain, and improves thermal stability and thermal degradation.

[0032] In this invention, the bandgap distribution of the polarized exciton lattice layer 106 has a function y = ax 3 +bx 2 +cx+d(a<0,△=4(b 2-3ac)<0) curve distribution. The polariton lattice layer has spatial inversion symmetry broken, forming a three-dimensional topological monopole, which controls the propagation of anisotropic polarons, making the electron-hole space on the Fermi surface contain inter-band nested vectors, increasing the motion speed of polaritons, inducing the formation of asymmetric barriers at the top and bottom of the active layer, increasing the tunneling probability of charge carriers, and enhancing the laser confinement factor and optical power.

[0033] In this invention, the dielectric constant distribution of the polarized exciton lattice layer 106 has a function y = e^x. 3 +fx 2 +gx+h(e>0,△=4(f 2 -3eg)<0 curve distribution. Reduce the dynamic conductivity caused by interband transitions, improve the uniformity of hole transport and injection in the active layer, suppress the generation of nonradiative charged excitons and Auger recombination of excitons and charges, enhance the laser confinement factor and optical power, enhance the cascade conversion between energy bands and spin-orbit coupling, enhance the high-level exciton occupation number inversion, and reduce the lasing threshold.

[0034] In this invention, the Al / C element ratio distribution of the polarized exciton lattice layer 106 has a fourth quadrant curve distribution of the function y = E + F*x / lnx.

[0035] The table below shows a comparison of data between a conventional laser and the laser of this invention.

[0036] Blue laser - Project Traditional lasers Laser of the present invention range of change Slope efficiency (W / A) 0.8 2.13 166％ <![CDATA[Threshold current density (kA / cm 2 )]]> 2.4 0.59 -75％ Optical power (W) 5.2 10.2 96％ Limiting factors 1.40％ 3.28％ 134％

[0037] In this invention, the active layer 103 is a periodic structure composed of a well layer and a barrier layer, with a period number of 3 ≥ m ≥ 1. The well layer is any one 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. The barrier layer can be 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, with a thickness of 10 to 200 angstroms.

[0038] In this invention, 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.

[0039] In this invention, the substrate 100 includes sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, sapphire / SiNx, and sapphire / SiO2 / SiN. x The composite substrate, or any one of the following: magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2, and LiGaO2 composite substrate.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A gallium nitride-based semiconductor laser device, comprising, from bottom to top, 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), characterized in that, A polarized exciton lattice layer (106) is provided between the upper waveguide layer (104) and the upper confinement layer (105); The electron mobility distribution of the polarized exciton lattice layer (106) has a function y = A + B * tanx curve distribution; The thermal conductivity distribution of the polarized exciton lattice layer (106) has a function y = C + D * cotx curve distribution; The bandgap distribution of the polarized exciton lattice layer (106) has the function y = ax 3 +bx 2 +cx+d(a<0,△=4(b 2 -3ac)<0) curve distribution; The dielectric constant distribution of the polarized exciton lattice layer (106) has the function y = e^x. 3 +fx 2 +gx+h(e>0,△=4(f 2 -3eg)<0 curve distribution; The Al / C element ratio distribution of the polarized exciton lattice layer (106) has a fourth quadrant curve distribution of the function y = E + F*x / lnx.

2. The gallium nitride-based semiconductor laser element according to claim 1, characterized in that, The polarized exciton lattice 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.

3. A gallium nitride-based semiconductor laser element according to claim 1, characterized in that, The active layer (103) is a periodic structure composed of a well layer and a barrier layer, with a period number of 3 ≥ m ≥ 1. The well layer is any one 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. Any combination, with a thickness of 10–100 angstroms, and the barrier layer being 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, with a thickness of 10–200 angstroms.

4. A gallium nitride-based semiconductor laser element according to claim 1, characterized in that, The lower confinement layer (101), lower waveguide layer (102), upper waveguide layer (104), and 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.

5. A gallium nitride-based semiconductor laser element according to claim 1, characterized in that, The substrate (100) includes sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, sapphire / SiNx, and sapphire / SiO2 / SiN. x The composite substrate, or any one of the following: magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2, and LiGaO2 composite substrate.

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