Gallium nitride-based semiconductor laser element

Abstract

The gallium nitride-based semiconductor laser element sequentially comprises a substrate, a lower limiting layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper limiting layer from bottom to top, and a polarization exciton lattice layer is arranged between the upper waveguide layer and the upper limiting layer. The polariton lattice layer has space inversion symmetry breaking, a three-dimensional topological monopole is formed, anisotropic polaron propagation is controlled, electron holes on the Fermi surface contain inter-band nested vectors, the movement rate of polaritons is increased, asymmetric barriers are formed at the top and the bottom of the active layer, the tunneling probability of carriers is increased, and the tunneling efficiency of the active layer is improved. And the laser limiting factor and the optical power are enhanced. The dynamic conductivity caused by inter-band transition is reduced, the transport and injection uniformity of holes in an active layer is improved, the generation of non-radiative charged excitons and Russhall recombination of excitons-charges are inhibited, the cascade conversion and spin-orbit coupling between energy bands are enhanced, the inversion of high-energy-level exciton occupancy numbers is enhanced, and the lasing threshold value is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor optoelectronic devices, and in particular to a gallium nitride-based semiconductor laser element. 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 significant 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 is up to KA / cm 2 , 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 increase of In component in quantum well will cause In component fluctuation and strain, broaden the gain spectrum of laser, and decrease the peak gain; the increase of In component in quantum well will cause poor thermal stability, and the growth of high-temperature p-type semiconductor and confinement layer will cause thermal degradation of active layer, which will reduce the quality of active layer and interface quality; the high defect density inside active layer, large mutual dissolution gap between InN and GaN, InN phase separation and segregation, thermal degradation, and unsatisfactory crystal quality will lead to unsatisfactory quantum well quality and interface quality, and increase non-radiative recombination centers;

[0010] 2. The activation energy of Mg acceptors in p-type semiconductors is large, the ionization efficiency is low, the hole concentration is much lower than the electron concentration, the hole mobility is much lower than the electron mobility, and the quantum well polarization electric field increases the hole injection barrier, holes overflow the active layer, and other problems. The hole injection is uneven and the efficiency is low, resulting in serious asymmetric mismatch between electrons and holes in the quantum well, electron leakage and carrier delocalization, making it more difficult for holes to transport in the quantum well, uneven carrier injection, and uneven gain. 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 the increase in the thickness of the lower confinement layer will limit the range of component regulation, which is prone to problems such as cracking, bending and quality degradation; at the same time, the light field is dissipated, and the light field mode leaks to the substrate to form a standing wave, which will lead to low substrate mode suppression efficiency and poor far-field image FFP quality. Summary of the invention

[0012] The present invention proposes a gallium nitride-based semiconductor laser element, which regulates atomic polarization so that atoms have electric dipole moments, forms ordered lattice layers of electric dipole moment interaction, tunes the rotational arrangement of the lattice, suppresses non-radiative recombination, and improves the lasing power and slope efficiency of the laser element.

[0013] The present invention provides 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, wherein a polariton lattice layer is provided between the upper waveguide layer and the upper confinement layer.

[0014] Preferably, the polaritonic lattice layer is 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, Ga 2 O 3, BN or any combination thereof.

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

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

[0017] Preferably, the bandgap width distribution of the polaritonic 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 polaritonic lattice layer has a function y=ex 3 +fx 2 +gx+h(e>0,△=4(f 2 -3eg)<0 curve distribution.

[0019] Preferably, the Al / C element ratio distribution of the polaritonic 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, the number of periods is 3≥m≥1, and the well layer is 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, Ga 2 O 3 , BN, any one or any combination thereof, with a thickness of 10 to 100 angstroms, and a barrier layer 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, Ga 2 O 3 , BN, any one or any combination thereof, with a thickness of 10 to 200 angstroms.

[0021] Preferably, the lower limiting layer, the lower waveguide layer, the upper waveguide layer, and the upper limiting layer are 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, Ga 2 O 3 , any one or any combination of BN.

[0022] Preferably, the substrate comprises sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO 2 Composite substrate, sapphire / AlN composite substrate, sapphire / SiNx, sapphire / SiO 2 / SiN x Composite substrate, magnesium aluminum spinel MgAl 2 O 4 、MgO、ZnO、ZrB 2 、LiAlO 2 and LiGaO 2 Any type of composite substrate.

[0023] Compared with the prior art, the gallium nitride-based semiconductor laser element provided by the embodiment of the present invention has the following beneficial effects: the polariton lattice layer has a broken spatial inversion symmetry, forming a three-dimensional topological monopole, controlling the propagation of anisotropic polaritons, making the electron-hole on the Fermi surface contain inter-band nesting vectors, increasing the movement rate of polaritons, inducing the formation of asymmetric potential barriers at the top and bottom of the active layer, increasing the tunneling probability of carriers, and enhancing the laser confinement factor and optical power. Reduce the dynamic conductivity caused by inter-band transitions, improve the transport and injection uniformity of holes in the active layer, inhibit the generation of non-radiative charged excitons and the Auger recombination of excitons and charges, enhance the laser confinement factor and optical power, and enhance the cascade conversion and spin-orbit coupling between energy bands, enhance the inversion of the high-energy-level exciton occupancy number, and reduce the lasing threshold. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0025] Figure 2 This is a SIMS secondary ion mass spectrum of a gallium nitride-based semiconductor laser element provided by the present invention.

[0026] In the figure, markings are as follows: 100: substrate; 101: lower confinement layer; 102: lower waveguide layer; 103: active layer; 104: upper waveguide layer, 105: upper confinement layer, 106: polariton lattice layer. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In order to solve the above problems, a gallium nitride-based semiconductor laser element provided in an embodiment of the present application will be introduced and explained in detail through the following specific embodiments.

[0029] Reference Figure 1-2 The present invention provides a gallium nitride-based semiconductor laser element, which includes, 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 polariton lattice layer 106 is provided between the upper waveguide layer 104 and the upper confinement layer 105. The polariton lattice layer 106 is 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, Ga 2 O 3 , BN or any combination thereof.

[0030] In the present invention, the electron mobility distribution of the polaritonic lattice layer 106 has a function y=A+B*tanx curve distribution. The atomic polarization is regulated to make the atoms have electric dipole moments, forming an orderly lattice layer of electric dipole moment interaction, tuning the rotational arrangement of the lattice, suppressing non-radiative recombination, and improving the lasing power and slope efficiency of the laser element.

[0031] In the present invention, the thermal conductivity distribution of the polaritonic lattice layer 106 has a function y=C+D*cotx curve distribution, which controls the exciton transport and exciton aggregation generated by the atoms in the active layer lattice being excited, suppresses the In component fluctuation and strain of the active layer, increases the peak gain, and improves thermal stability and thermal degradation.

[0032] In the present invention, the bandgap width distribution of the polariton 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 a broken spatial inversion symmetry, forming a three-dimensional topological monopole, controlling the propagation of anisotropic polaritons, making the electron-hole interband nesting vector on the Fermi surface, increasing the movement rate of polaritons, inducing the formation of asymmetric potential barriers at the top and bottom of the active layer, increasing the tunneling probability of carriers, and enhancing the laser confinement factor and optical power.

[0033] In the present invention, the dielectric constant distribution of the polaritonic lattice layer 106 has a function y=ex 3 +fx 2 +gx+h(e>0,△=4(f 2 -3eg)<0 curve distribution. Reduce the dynamic conductivity caused by inter-band transition, improve the transport and injection uniformity of holes in the active layer, inhibit the generation of non-radiative charged excitons and the Auger recombination of excitons and charges, enhance the laser confinement factor and optical power, enhance the cascade conversion and spin-orbit coupling between energy bands, enhance the inversion of high-energy-level exciton occupancy number, and reduce the lasing threshold.

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

[0035] The specific data are shown in the following table, which compares the data of the traditional laser and the laser of the present invention.

[0036] Blue Laser Project Conventional laser 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 Factor 1.40％ 3.28％ 134％

[0037] In the present invention, the active layer 103 is a periodic structure composed of a well layer and a barrier layer, the number of periods is 3≥m≥1, and the well layer is 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, Ga 2 O 3, BN, any one or any combination thereof, with a thickness of 10 to 100 angstroms, and a barrier layer 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, Ga 2 O 3 , BN, any one or any combination thereof, with a thickness of 10 to 200 angstroms.

[0038] In the present invention, the lower confinement layer 101, the lower waveguide layer 102, the upper waveguide layer 104, and the upper confinement layer 105 are 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, Ga 2 O 3 , any one or any combination of BN.

[0039] In the present invention, the substrate 100 includes sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO 2 Composite substrate, sapphire / AlN composite substrate, sapphire / SiNx, sapphire / SiO 2 / SiN x Composite substrate, magnesium aluminum spinel MgAl 2 O 4 、MgO、ZnO、ZrB 2 、LiAlO 2 and LiGaO 2 Any type of composite substrate.

[0040] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A gallium nitride-based semiconductor laser element, 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 polariton lattice layer (106) is provided between the upper waveguide layer (104) and the upper confinement layer (105).

2. The gallium nitride-based semiconductor laser device according to claim 1, characterized in that: The polariton 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. The gallium nitride-based semiconductor laser device according to claim 1, characterized in that: The electron mobility distribution of the polariton lattice layer (106) has a function y=A+B*tanx curve distribution.

4. The gallium nitride-based semiconductor laser device according to claim 1, characterized in that: The thermal conductivity distribution of the polaritonic lattice layer (106) has a function y=C+D*cotx curve distribution.

5. The gallium nitride-based semiconductor laser device according to claim 1, characterized in that: The bandgap width distribution of the polariton lattice layer (106) has a function y=ax 3 +bx 2 +cx+d(a<0,△=4(b 2 -3ac)<0) curve distribution.

6. The gallium nitride-based semiconductor laser device according to claim 1, characterized in that: The dielectric constant distribution of the polaritonic lattice layer (106) has a function y=ex 3 +fx 2 +gx+h(e>0,△=4(f 2 -3eg)<0 curve distribution.

7. The gallium nitride-based semiconductor laser device according to claim 1, characterized in that: The Al / C element ratio distribution of the polariton lattice layer (106) has a fourth quadrant curve distribution of the function y=E+F*x / lnx.

8. The gallium nitride-based semiconductor laser device according to claim 1, characterized in that: The active layer (103) is a periodic structure composed of a well layer and a barrier layer, the number of periods is 3≥m≥1, and 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, BN or Any combination, with a thickness of 10 to 100 angstroms, and the barrier layer is any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, and BN, with a thickness of 10 to 200 angstroms.

9. The gallium nitride-based semiconductor laser device according to claim 1, characterized in that: 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.

10. The gallium nitride-based semiconductor laser device 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, sapphire / SiO2 / SiN x Any one of a composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

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