Gallium nitride-based semiconductor purple light and ultraviolet light laser

Abstract

The invention discloses a gallium nitride-based semiconductor purple light and ultraviolet light laser which 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 strain photoelectric coupling layer is arranged between the upper waveguide layer and the upper limiting layer. By designing specific thermal expansion coefficient distribution, electron affinity distribution and Al / In element proportion distribution and changing electron nematic property, the strain photoelectric coupling layer eliminates sub-band gap emission states with overlapped spectrums, inhibits mode jump in the vertical direction, generates single-mode laser, obtains a good FFP far-field pattern, enhances exciton response of the active layer, and improves the performance of the FFP far-field pattern. The driving voltage and the excitation threshold of the laser element are reduced, the limiting factor is enhanced, the substrate mode leakage is inhibited, and the lasing power, the slope efficiency and the far-field image quality of the laser element are improved.

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 violet ultraviolet laser. 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 large internal lattice mismatch and strain cause strong polarization effect, and the QCSE quantum confined Stark effect strongly limits the improvement of the laser lasing gain;

[0010] 2) 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.

[0011] 3) The leakage of the light field mode into the substrate to form standing waves will lead to low efficiency of substrate mode suppression and poor far-field pattern FFP. Summary of the invention

[0012] The present invention proposes a gallium nitride-based semiconductor violet ultraviolet laser. By designing a specific thermal expansion coefficient distribution, electron affinity energy distribution and Al / In element ratio distribution, the electron nematicity is changed, so that the strained photoelectric coupling layer eliminates the spectrally overlapping sub-bandgap emission state, suppresses mode hopping in the vertical direction, generates single-mode laser, obtains a good FFP far-field pattern, enhances the exciton response of the active layer, reduces the driving voltage and excitation threshold of the laser element, enhances the confinement factor, suppresses substrate mode leakage, and improves the lasing power, slope efficiency and far-field image quality of the laser element.

[0013] The present invention provides a gallium nitride-based semiconductor ultraviolet laser, 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 strained photoelectric coupling layer is provided between the upper waveguide layer and the upper confinement layer.

[0014] The strained photoelectric coupling 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 deformation potential distribution of the strained photoelectric coupling layer has a function y=kx 3 +m*x 2 +n*x+p(k<0,△=4(m 2 -3kn)<0) curve distribution.

[0016] Preferably, the electron effective mass distribution of the strained photoelectric coupling layer has a function y=ax 3 +bx 2 +cx+d(a<0,△=4(b 2 -3ac)<0) curve distribution.

[0017] Preferably, the thermal expansion coefficient distribution of the strained photoelectric coupling layer has a function y=jx 3 +fx 2 +gx+h(j<0,△=4(f 2 -3eg)<0 curve distribution.

[0018] Preferably, the elastic coefficient distribution of the strained photoelectric coupling layer has a function y=A+B*cotx curve distribution.

[0019] Preferably, the electron affinity energy distribution of the strained photoelectric coupling layer has a function y=C+D*x+E*sinx curve distribution.

[0020] Preferably, the Al / In element ratio distribution of the strained photoelectric coupling layer has a function y=F+G*arccosx curve distribution.

[0021] Preferably, the active layer is a periodic structure composed of a well layer and a barrier layer, the number of periods is 3≥m≥1, and the well layer is any one 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.

[0022] 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.

[0023] 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.

[0024] Compared with the prior art, the gallium nitride-based semiconductor ultraviolet laser provided in the embodiment of the present invention has the following beneficial effects:

[0025] 1. The strain photoelectric coupling layer applies local strain at the interface between the upper confinement layer and the upper waveguide layer by designing a specific deformation potential distribution, elastic coefficient distribution and electron effective mass distribution, creates a strain field, regulates the degree of interface bending, and makes the interface strain-induced polarization modulate the laser, enhances the strain photoelectric coupling effect of piezoelectric polarization and charge transfer, regulates the distribution of electron and hole carriers, reduces the quantum confinement Stark effect, reduces the hole injection barrier, regulates the carrier conduction, generation, recombination and separation process of the active layer, improves the overlap ratio of the electron and hole wave functions in the active layer, and improves the gain uniformity, electro-lasing gain and optical power of the laser.

[0026] 2. The strained photoelectric coupling layer changes the electron nematicity by designing a specific thermal expansion coefficient distribution, electron affinity energy distribution and Al / In element ratio distribution, so that the strained photoelectric coupling layer eliminates the spectrally overlapping sub-bandgap emission state, suppresses mode hopping in the vertical direction, generates single-mode laser, obtains a good FFP far-field pattern, enhances the exciton response of the active layer, reduces the driving voltage and excitation threshold of the laser element, enhances the confinement factor, suppresses substrate mode leakage, and improves the laser element's lasing power, slope efficiency and far-field image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1A schematic structural diagram of a gallium nitride-based semiconductor violet ultraviolet laser provided by the present invention.

[0028] Figure 2 This is a SIMS secondary ion mass spectrum of a gallium nitride-based semiconductor violet ultraviolet laser provided by the present invention.

[0029] 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: strained photoelectric coupling layer. DETAILED DESCRIPTION

[0030] 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.

[0031] In order to solve the above problems, a gallium nitride-based semiconductor ultraviolet laser provided in an embodiment of the present application will be introduced and explained in detail through the following specific embodiments.

[0032] Reference Figure 1-2 The present invention provides a gallium nitride-based semiconductor ultraviolet laser, 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, wherein a strained photoelectric coupling layer 106 is provided between the upper waveguide layer 104 and the upper confinement layer 105.

[0033] The strained photoelectric coupling 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, BN, and diamond.

[0034] The strain potential distribution of the strain photoelectric coupling layer 106 has a function y=kx 3 +m*x 2 +n*x+p(k<0,△=4(m 2 -3kn)<0) curve distribution.

[0035] The electron effective mass distribution of the strained photoelectric coupling layer 106 has a function y=ax 3 +bx 2 +cx+d(a<0,△=4(b 2 -3ac)<0) curve distribution.

[0036] The elastic coefficient distribution of the strained photoelectric coupling layer 106 has a function y=A+B*cotx curve distribution.

[0037] The strain photoelectric coupling layer 106 applies local strain at the interface between the upper confinement layer 105 and the upper waveguide layer 104 by designing a specific deformation potential distribution, elastic coefficient distribution and electron effective mass distribution, creates a strain field, regulates the degree of interface bending, and makes the interface strain-induced polarization modulate the laser, enhances the strain photoelectric coupling effect of piezoelectric polarization and charge transfer, regulates the distribution of electron and hole carriers, reduces the quantum confinement Stark effect, reduces the hole injection barrier, regulates the carrier conduction, generation, recombination and separation process of the active layer, improves the overlap ratio of the electron and hole wave functions in the active layer, and improves the gain uniformity, electro-lasing gain and optical power of the laser.

[0038] The thermal expansion coefficient distribution of the strained photoelectric coupling layer 106 has a function y=jx 3 +fx 2 +gx+h(j<0,△=4(f 2 -3eg)<0 curve distribution.

[0039] The electron affinity energy distribution of the strained photoelectric coupling layer 106 has a function y=C+D*x+E*sinx curve distribution.

[0040] The Al / In element ratio distribution of the strained photoelectric coupling layer 106 has a function y=F+G*arccosx curve distribution.

[0041] The strained photoelectric coupling layer 106 changes the electron nematicity by designing a specific thermal expansion coefficient distribution, electron affinity energy distribution and Al / In element ratio distribution, so that the strained photoelectric coupling layer eliminates the spectrally overlapping sub-bandgap emission state, suppresses mode hopping in the vertical direction, generates single-mode laser, obtains a good FFP far-field pattern, enhances the exciton response of the active layer, reduces the driving voltage and excitation threshold of the laser element, enhances the confinement factor, suppresses substrate mode leakage, and improves the lasing power, slope efficiency and far-field image quality of the laser element.

[0042] The specific data are shown in the following table, which compares the data of the traditional laser and the laser of the present invention.

[0043]

[0044]

[0045] 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 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 one or any combination thereof, 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.

[0046] 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 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.

[0047] In the present invention, 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.

[0048] 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 ultraviolet laser, 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 strained photoelectric coupling layer (106) is provided between the upper waveguide layer (104) and the upper confinement layer (105), The strained photoelectric coupling 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.

2. The gallium nitride-based semiconductor ultraviolet laser according to claim 1, characterized in that: The deformation potential distribution of the strain photoelectric coupling layer (106) has a function y=kx 3 +m*x 2 +n*x+p(k<0,△=4(m 2 -3kn)<0) curve distribution.

3. The gallium nitride-based semiconductor ultraviolet laser according to claim 1, characterized in that: The electron effective mass distribution of the strained photoelectric coupling layer (106) has a function y=ax 3 +bx 2 +cx+d(a<0,△=4(b 2 -3ac)<0) curve distribution.

4. The gallium nitride-based semiconductor ultraviolet laser according to claim 1, characterized in that: The thermal expansion coefficient distribution of the strained photoelectric coupling layer (106) has a function y=jx 3 +fx 2 +gx+h(j<0,△=4(f 2 -3eg)<0 curve distribution.

5. The gallium nitride-based semiconductor ultraviolet laser according to claim 1, characterized in that: The elastic coefficient distribution of the strained photoelectric coupling layer (106) has a function y=A+B*cotx curve distribution.

6. The gallium nitride-based semiconductor violet ultraviolet laser according to claim 1, characterized in that: The electron affinity energy distribution of the strained photoelectric coupling layer (106) has a function y=C+D*x+E*sinx curve distribution.

7. The gallium nitride-based semiconductor violet ultraviolet laser according to claim 1, characterized in that: The Al / In element ratio distribution of the strained photoelectric coupling layer (106) has a function y=F+G*arccosx curve distribution.

8. The gallium nitride-based semiconductor violet ultraviolet laser 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 violet ultraviolet laser 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 ultraviolet laser 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 / 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.

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