A semiconductor laser element

Abstract

The present invention relates to the technical field of semiconductor optoelectronic devices, and in particular to a semiconductor laser element, which comprises, from bottom to top, a substrate, an n-layer cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, a p-type cladding layer and a p-type semiconductor, wherein the active layer is In b Ga 1‑b N / In c Al d Ga 1‑c‑d N, n-type cladding layer has at least 3 Al gradient layers Al e Ga 1‑e N / A f In g Ga 1‑f‑g N / A h Ga 1‑ h N, there is an Al composition gradient between the n-type cladding layers and an Al composition gradient between the active layer: Al composition e>h>f≥d, Al f In g Ga 1‑f‑g The In component gradient formed by N and the active layer, upper waveguide layer, and lower wave layer constitutes the In component gradient. The polarization effect is regulated by the double gradient combination, the fluctuation and strain of the In component in the active layer are reduced, the gain spectrum width of the laser element is reduced, the exciton oscillator strength and peak gain are enhanced, the thermal stability of the active layer is improved, and the strong coupling of exciton-photons at room temperature is achieved, ultimately forming stable exciton-polariton lasing.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor optoelectronic devices, and in particular to a semiconductor laser element with an n-type cladding layer for improving exciton-polariton lasing. Background Art

[0002] Lasers are widely used in display, communication, medical treatment, weapons, guidance, ranging, cutting, welding 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, semiconductor lasers have the advantages of small size, light weight, long life and simple structure. There are big differences between lasers and nitride semiconductor light-emitting diodes. 1) Lasers are generated by stimulated radiation of carriers, with a small half-width of the spectrum and high brightness. The output power of a single laser can be in the W level, while nitride semiconductor light-emitting diodes are spontaneous radiation, and the output power of a single light-emitting diode is in the mW level; 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; 3) Light-emitting diodes The tube spontaneously radiates, without any external influence, and it is incoherent light that transitions from high energy level to low energy level, while the laser is stimulated transition radiation, and the energy of the induced photon should be equal to the difference in energy levels of the electron transition, producing photons and induced photons that are completely coherent light; 4) Different principles: Under the action of external voltage, the light-emitting diode produces radiation recombination and luminescence when electron holes transition to the quantum well or pn junction, while the laser needs the lasing conditions to be met before it can be lased. The carrier inversion distribution in the active area must be met, and the stimulated radiation light oscillates back and forth in the resonant cavity. The propagation in the gain medium amplifies the light, meets the threshold condition so that the gain is greater than the loss, and finally outputs the laser.Nitride semiconductor lasers have the following problems: 1) Large internal lattice mismatch and strain cause strong polarization effect, and the strong QCSE quantum confinement Stark effect limits the improvement of laser electro-lasing gain; 2) High internal defect density and unsatisfactory crystal quality; 3) 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, and the hole mobility is much lower than the electron mobility, resulting in serious asymmetric mismatch between electrons and holes in quantum wells; 4) Electron leakage; 5) Low hole injection efficiency; 6) Carrier delocalization; 7) Strong Auger recombination; 8) High optical waveguide absorption loss; 9) Low quantum well luminescence efficiency; 10) Poor p-type resistance and ohmic contact, etc. The following difficulties exist in the production of traditional nitride semiconductor lasers: 1) The increase of In component in quantum well will produce In component fluctuation and strain, the gain spectrum of laser will become wider, and the peak gain will decrease; 2) The increase of In component in quantum well will deteriorate the thermal stability; 3) In is easy to produce segregation; 4) The step difference of valence band of laser will increase, the hole transport in quantum well will be more difficult, the carrier injection will be uneven, and the gain will be uneven; 5) The refractive index dispersion of laser will decrease with the increase of wavelength, resulting in the decrease of mode gain of laser; 6) After laser lasing, the carrier concentration in active region of multi-quantum well will be saturated, the bipolar conductivity effect will be weakened, the series resistance of laser will increase, resulting in the increase of laser voltage; 7) High dislocation density will reduce the life of laser; 8) Intrinsic carbon impurities in p-type semiconductor will compensate acceptors and destroy p-type, etc. Summary of the invention

[0003] In order to solve the above technical problems, the Al composition gradient between the Al gradient layers of the n-type cladding layer and the active layer is provided. f In g Ga 1-f-g The In component gradient formed by N and the active layer, the upper waveguide layer and the lower waveguide layer constitutes a double gradient combination of Al component and In component, forming an exciton polariton lasing structure and a gain waveguide structure.

[0004] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0005] A semiconductor laser element, comprising, from bottom to top, a substrate, an n-type cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, a p-type cladding layer, and a p-type semiconductor, wherein the n-type cladding layer has an exciton polariton lasing structure and a gain waveguide structure, wherein the active layer is In b Ga 1-b N / In c Al d Ga 1-c-d N composed of a periodic structure, in which the well layer is In b Ga 1- b N, the barrier layer is In cAl d Ga 1-c-d N; the n-type cladding layer has at least 3 Al gradient layers Al e Ga 1-e N / A f In g Ga 1-f-g N / A h Ga 1- h N, the n-type cladding layer has an Al composition gradient between the layers and the barrier layer In of the active layer c Al d Ga 1-c-d An Al composition gradient is also formed between N: Al composition e>h>f≥d.

[0006] In the above technical solution, the n-type cladding layer has at least three Al gradient layers Al e Ga 1-e N / A f In g Ga 1-f-g N / A h Ga 1-h N, Al ion intensity gradient measured by SIMS secondary ion mass spectrometry: 20≥e / h≥4, 200≥e / f≥50, 50≥g / f≥10.

[0007] In the above technical solution, the n-type cladding layer has at least three Al gradient layers Al e Ga 1-e N / A f In g Ga 1-f-g N / A h Ga 1-h N, the Al ion intensity gradients tested by SIMS secondary ion mass spectrometry are 1E20~5E20 (au), 5E17~5E18 (au), and 1E19~5E19 (au), respectively.

[0008] In the above technical solution, the n-type cladding layer has at least three Al gradient layers Al e Ga 1-e N / A f In g Ga 1-f-g N / A h Ga 1-h N, among which Al f In g Ga 1-f-g The In component of the N layer is g, and the upper waveguide layer is In y Ga 1-y N, the lower waveguide layer is In z Ga1- z N, Al in the n-type cladding layer f In g Ga 1-f-g N and the well layer In of the active layer b Ga 1-b N. The upper waveguide layer and the lower waveguide layer form an In composition gradient: b≥g≥z≥y.

[0009] In the above technical solution, the n-type cladding layer has at least three Al gradient layers Al e Ga 1-e N / A f In g Ga 1-f-g N / A h Ga 1-h N, among which Al f In g Ga 1-f-g The In ion intensity of the N layer measured by SIMS secondary ion mass spectrometry is 2E20~5E20 (au).

[0010] In the above technical solution, the Al gradient layers of the n-type cladding layer have an Al composition gradient and are connected to the barrier layer In of the active layer. c Al d Ga 1-c-d N also forms an Al composition gradient: Al composition e>h>f≥d; the Al in the n-type cladding layer f In g Ga 1-f-g N and the well layer In of the active layer b Ga 1-b N. The upper waveguide layer and the lower waveguide layer form an In component gradient: b≥g≥z≥y, and the two constitute a double gradient combination of Al component and In component.

[0011] In the above technical solution, the Al gradient layer between the n-type cladding layer and the barrier layer In c Al d Ga 1-c-d The Al composition gradient between N and Al in the n-type cladding layer f In g Ga 1-f-g N and the well layer In of the active layer b Ga 1-bN. The In component gradients formed by the upper waveguide layer and the lower wave layer together constitute a double gradient combination of Al component and In component, and finally form an exciton-polariton lasing structure. The polarization effect is regulated by the double gradient combination, the fluctuation and strain of the In component in the active layer are reduced, the gain spectrum width of the laser element is reduced, the exciton oscillator strength and peak gain are enhanced, the thermal stability of the active layer is improved, and the strong coupling of excitons and photons at room temperature is realized, finally forming a stable exciton-polariton lasing.

[0012] In the above technical solution, the Al gradient layer between the n-type cladding layer and the barrier layer In c Al d Ga 1-c-d The Al composition gradient between N and Al in the n-type cladding layer f In g Ga 1-f-g N and the well layer In of the active layer b Ga 1-b N, the In component gradient formed by the upper waveguide layer and the lower waveguide layer together constitutes a double gradient combination of Al component and In component, which together form a gain waveguide structure, enhance the optical confinement effect, limit the internal loss by more than 50%, and at the same time, reduce the room temperature threshold voltage to 5.5V, and the threshold current to 5KA / cm 2 , the slope efficiency rises to 0.6W / A, and the continuous working life at room temperature can be increased to 10,000 hours.

[0013] In the above technical scheme, the n-layer cladding layer, the lower waveguide layer, the active layer, the upper waveguide layer, the electron blocking layer, the p-type cladding layer, and the p-type semiconductor include any one or any combination of GaN, AlGaN, InGaN, AlInGaN, AlN, InN, AlInN, SiC, Ga2O3, BN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, AlInAs, AlInP, AlGaP, and InGaP.

[0014] In the above technical scheme, the substrate includes any one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, sapphire / SiNx, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0015] Compared with the prior art, the invention has the advantages that the Al composition gradient between the Al gradient layers of the n-type cladding layer and the active layer is f In g Ga 1-f-gThe In component gradient formed by N and the active layer, upper waveguide layer, and lower waveguide layer constitutes a double gradient combination of Al component and In component, forming an exciton polariton lasing structure and a gain waveguide structure. The double gradient combination is used to regulate the polarization effect, reduce the fluctuation and strain of the In component in the active layer, reduce the gain spectrum width of the laser element, increase the exciton oscillator strength and peak gain, improve the thermal stability of the active layer, achieve strong coupling of excitons and photons at room temperature, and finally form stable exciton polariton lasing; the double gradient combination also forms a gain waveguide structure, enhances the optical confinement effect, limits the internal loss by more than 50%, and at the same time, reduces the room temperature threshold voltage to 5.5V and the threshold current to 5KA / cm 2 , the slope efficiency rises to 0.6W / A, and the continuous working life at room temperature can be increased to 10,000 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of a semiconductor laser element having an n-type cladding layer for improving exciton polaritons according to an embodiment of the present invention;

[0017] Figure 2 is a SIMS secondary ion mass spectrum of a semiconductor laser element having an n-type cladding layer for improving exciton polaritons according to an embodiment of the present invention;

[0018] Reference numerals:

[0019] 100: substrate; 101: n-type cladding layer; 101a: Al e Ga 1-e N; 101b:Al f In g Ga 1-f-g N; 101c:Al h Ga 1-h N; 102: lower waveguide layer; 103: active layer; 104: upper waveguide layer, 105: electron blocking layer, 106: p-type cladding layer, 107: p-type semiconductor. DETAILED DESCRIPTION

[0020] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0021] Please refer to Figure 1 A semiconductor laser element according to an embodiment of the present invention includes, from bottom to top, a substrate 100, an n-type cladding layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, an electron blocking layer 105, a p-type cladding layer 106, and a p-type semiconductor 107.

[0022] Among them, the substrate 100 is a substrate on which nitride semiconductor crystals can be epitaxially grown, which is used to support the epitaxial materials of each layer of the semiconductor laser element, and can be selected to use a substrate that has a high transmittance in the wavelength range of light emitted by the semiconductor light-emitting element (for example, the transmittance of the light is above 50%). For example, the substrate 100 includes but is not limited to any one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, sapphire / SiNx, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrates.

[0023] The n-type cladding layer 101 is made on the substrate 100, and its lattice constant matches the lattice constant of the substrate 100. The so-called lattice constant matching means that the lattice constant of the epitaxial material is consistent with the lattice constant of the substrate, and there is no stress between the two during epitaxial growth. The n-type cladding layer 101 limits the light emitted from the active area, so that the light emitted from the active area propagates along the waveguide axis. Preferably, the growth thickness of the n-type cladding layer 101 is 0-3000nm, and the n-type cladding layer has an exciton polariton lasing structure and a gain waveguide structure. The exciton polariton lasing structure consists of the following structures: the active layer is In b Ga 1-b N / In c Al d Ga 1-c-d N composed of a periodic structure, in which the well layer is In b Ga 1-b N, the barrier layer is In c Al d Ga 1-c-d N; the n-type cladding layer has at least 3 Al gradient layers Al e Ga 1-e N101a / Al f In g Ga 1-f-g N101b / Al h Ga 1-h N101c, the n-type cladding layer has an Al composition gradient between the layers and the barrier layer In of the active layer c Al d Ga 1-c-dN also forms an Al component gradient: Al component e>h>f≥d; Preferably, the growth temperature of the n-type cladding layer 101 is 700℃~1200℃, the growth pressure is 200mbar~500mbar, and the growth rate is 0.01nm / s~0.5nm / s. When the growth temperature is lower than 700℃, although the low temperature is conducive to the incorporation of the indium element, the migration length of the aluminum atoms at low temperature is very small, resulting in the deterioration of the material morphology and the decrease of the material quality; when the temperature is higher than 900℃, the high temperature will make the indium content extremely low or even disappear; when the growth temperature is lower than 700℃, the indium content will be very low or even disappear. When the pressure is lower than 200 mbar, the carbon impurity content in the material increases sharply, causing the electrical quality of the crystal to deteriorate; when the growth pressure is higher than 500 mbar, the TMAl introduced during the growth process will undergo severe pre-reaction with ammonia in the gas phase, resulting in reduced growth efficiency; and when the growth rate is lower than 0.01 nm / s, the lower growth rate will help improve the material quality, but the production efficiency will be reduced, and it may take dozens of hours to grow an n-type cladding layer 101 of sufficient thickness; when the growth rate is higher than 0.5 nm / s, high-speed growth will reduce the material quality.

[0024] As a preferred embodiment of the above technical solution, the n-type cladding layer 101 has at least three layers of Al gradient layers Al stacked in sequence. e Ga 1-e N101a / Al f In g Ga 1-f-g N101b / Al h Ga 1-h N101c, Al ion intensity gradient measured by SIMS secondary ion mass spectrometry: 20≥e / h≥4, 200≥e / f≥50, 50≥g / f≥10.

[0025] In a specific implementation of the above technical solution, please refer to Figure 2 The n-type cladding layer has three layers of Al gradient layers stacked in sequence. e Ga 1-e N101a / Al f In g Ga 1-f-g N101b / Al h Ga 1-h N101c, the Al ion intensity gradients tested by SIMS secondary ion mass spectrometry are 1E20~5E20 (au), 5E17~5E18 (au), and 1E19~5E19 (au), respectively.

[0026] The lower waveguide layer 102 is made on the n-type cladding layer 101, and its lattice constant matches the lattice constant of the substrate 100. It serves as a carrier confinement layer for light conduction, improving the electron-hole recombination efficiency, and increasing the operating temperature of the laser element. Preferably, the lower waveguide layer 102 is grown to a thickness of 30-2000nm.

[0027] The active layer 103 is made on the lower waveguide layer 102 and is the light-emitting region of the device. It can be an active region structure of various semiconductor inter-band and inter-sub-band light-emitting regions. In the present invention, the active layer 103 is In b Ga 1-b N / In c Al d Ga 1-c-d N composed of a periodic structure, in which the well layer is In b Ga 1-b N, the barrier layer is In c Al d Ga 1-c-d N.

[0028] The upper waveguide layer 104 is made on the active layer 103, and its lattice constant matches the lattice constant of the substrate 100. As a carrier confinement layer, the carriers are confined in the active layer 103, thereby improving the electron-hole recombination efficiency and the operating temperature of the laser element; preferably, the growth thickness of the upper waveguide layer 104 is 30-2000nm.

[0029] The electron blocking layer 105 is made on the upper waveguide layer 104. Since the effective mass of electrons is small and the movement speed is high under the action of the electric field, they can easily escape from the quantum well area of ​​the luminous active layer 103. Setting up the electron blocking layer 105 near the p-side can effectively prevent the escape of electrons. When the semiconductor element is working, electrons are injected into the n-side and holes are injected into the p-side. The electrons and holes meet and recombine in the quantum well area of ​​the active layer 103 to emit light.

[0030] The p-type cladding layer 106 is formed on the electron blocking layer 105 to limit the light emitted by the active layer 103 so that the light emitted by the active layer 103 propagates along the waveguide axis. Preferably, the p-type cladding layer 106 has a growth thickness of 500-4000 nm.

[0031] The p-type semiconductor 107 is made on the p-type cladding layer 106. The n-layer cladding layer 101, the lower waveguide layer 102, the active layer 103, the upper waveguide layer 104, the electron blocking layer 105, the p-type cladding layer 106, and the p-type semiconductor 107 are sequentially stacked on the substrate 100. The stacked semiconductor layers are stacked by metal organic chemical vapor deposition (MOCVD), metal organic vapor phase epitaxy (MOVPE), molecular beam epitaxy (MBE), and hydride vapor phase epitaxy (HVPE). The n-layer cladding layer 101 is made on the p-type cladding layer 106. The n-layer cladding layer 101, the lower waveguide layer 102, the active layer 103, the upper waveguide layer 104, the electron blocking layer 105, the p-type cladding layer 106, and the p-type semiconductor 107 are sequentially stacked on the substrate 100. The stacked semiconductor layers are stacked by metal organic chemical vapor deposition (MOCVD), metal organic vapor phase epitaxy (MOVPE), molecular beam epitaxy (MBE), and hydride vapor phase epitaxy (HVPE). 01, the lower waveguide layer 102, the active layer 103, the upper waveguide layer 104, the electron blocking layer 105, the p-type cladding layer 106 and the p-type semiconductor 107 include any one or any combination of GaN, AlGaN, InGaN, AlInGaN, AlN, InN, AlInN, SiC, Ga2O3, BN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, AlInAs, AlInP, AlGaP, and InGaP.

[0032] As a further optimization of the above technical solution, the n-type cladding layer 101 has at least three layers of Al gradient layers Al stacked in sequence. e Ga 1-e N101a / Al f In g Ga 1-f-g N101b / Al h Ga 1-h N101c, of which Al f In g Ga 1-f-g The In component of the N101b layer is g, and the upper waveguide layer 104 is In y Ga 1-y N, the lower waveguide layer 102 is In z Ga 1-z N, Al in the n-type cladding layer f In g Ga 1-f- g N101b and the well layer In of the active layer 103 b Ga 1-b N, the upper waveguide layer 104 and the lower waveguide layer 102 form an In composition gradient: b≥g≥z≥y; the three Al gradient layers of the n-type cladding layer 101 have an Al composition gradient between them, and the barrier layer In of the active layer 103 c Al d Ga 1-c-dAn Al component gradient is also formed between N, thus forming a double gradient combination of Al component and In component. On the one hand, this double gradient combination forms an exciton polariton lasing structure. Through the double gradient combination, the polarization effect is regulated, the fluctuation and strain of the In component in the active layer are reduced, the gain spectrum width of the laser element is reduced, the exciton oscillator strength and peak gain are increased, the thermal stability of the active layer is improved, and the strong coupling of excitons and photons at room temperature is achieved, and finally stable exciton polariton lasing is formed; on the other hand, a gain waveguide structure is formed. The gain waveguide structure enhances the optical confinement effect and the waveguide effect of the laser gain, limits the internal loss by more than 50%, and at the same time, reduces the room temperature threshold voltage to 5.5V and the threshold current to 5KA / cm 2 , the slope efficiency rises to 0.6W / A, and the continuous working life at room temperature can be increased to 10,000 hours.

[0033] As a specific implementation of the above technical solution, please refer to Figure 2 The n-type cladding layer 101 has three Al gradient layers stacked in sequence. e Ga 1-e N101a / Al f In g Ga 1-f-g N101b / Al h Ga 1-h N101c, where Al f In g Ga 1-f-g The In ion intensity of the N101b layer measured by SIMS secondary ion mass spectrometry is 2E20~5E20 (au).

[0034] 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 semiconductor laser element, characterized in that: The structure includes, from bottom to top, a substrate, an n-type cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, a p-type cladding layer and a p-type semiconductor, wherein the n-type cladding layer has an exciton polariton lasing structure and a gain waveguide structure, wherein the active layer is In b Ga 1-b N / In c Al d Ga 1-c-d N composed of a periodic structure, in which the well layer is In b Ga 1-b N, the barrier layer is In c Al d Ga 1-c-d N; the n-type cladding layer has at least 3 Al gradient layers Al e Ga 1-e N / A f In g Ga 1-f-g N / A h Ga 1-h N, the n-type cladding layer has an Al composition gradient between the layers and the barrier layer In of the active layer c Al d Ga 1-c-d Al composition gradient is also formed between N: Al composition e>h>f≥d; among which Al f In g Ga 1-f-g The In component of the N layer is g, and the upper waveguide layer is In y Ga 1-y N, the lower waveguide layer is In z Ga 1-z N, Al in the n-type cladding layer f In g Ga 1-f-g N and the well layer In of the active layer b Ga 1-b N. The upper waveguide layer and the lower waveguide layer form an In component gradient: b≥g≥z≥y, and the two constitute a double gradient combination of Al component and In component.

2. A semiconductor laser element according to claim 1, characterized in that: The n-type cladding layer has at least three Al gradient layers Al e Ga 1-e N / A f In g Ga 1-f-g N / A h Ga 1-h N, Al ion strength gradient 20≥e / h≥4, 200≥e / f≥50, 50≥g / f≥10.

3. A semiconductor laser element as claimed in claim 2, characterized in that: The n-type cladding layer has at least three Al gradient layers Al e Ga 1-e N / A f In g Ga 1-f-g N / A h Ga 1-h The N and Al ion strength gradients are 1E20~5E20a.u., 5E17~5E18a.u., and 1E19~5E19a.u., respectively.

4. A semiconductor laser element as claimed in claim 3, characterized in that: The n-type cladding layer has at least three Al gradient layers Al e Ga 1-e N / A f In g Ga 1-f-g N / A h Ga 1-h N, among which Al f In g Ga 1-f-g The In ion strength of the N layer is 2E20~5E20a.u.

5. A semiconductor laser element as claimed in claim 4, characterized in that: The Al gradient layer between the n-type cladding layer and the barrier layer In of the active layer c Al d Ga 1-c-d The Al composition gradient between N and Al in the n-type cladding layer f In g Ga 1-f-g N and the well layer In of the active layer b Ga 1-b N. The In component gradients formed by the upper waveguide layer and the lower wave layer together constitute a double gradient combination of Al component and In component, and finally form an exciton-polariton lasing structure. The polarization effect is regulated by the double gradient combination, the fluctuation and strain of the In component in the active layer are reduced, the gain spectrum width of the laser element is reduced, the exciton oscillator strength and peak gain are enhanced, the thermal stability of the active layer is improved, and the strong coupling of excitons and photons at room temperature is realized, finally forming stable exciton-polariton lasing.

6. A semiconductor laser element as claimed in claim 5, characterized in that: The Al gradient layer between the n-type cladding layer and the barrier layer In of the active layer c Al d Ga 1-c-d The Al composition gradient between N and Al in the n-type cladding layer f In g Ga 1-f-g N and the well layer In of the active layer b Ga 1-b N. The In component gradient formed by the upper waveguide layer and the lower waveguide layer constitutes a double gradient combination of Al component and In component, which together form a gain waveguide structure, enhance the optical confinement effect, reduce the internal loss by more than 50%, and at the same time, reduce the room temperature threshold voltage to 5.5V, and the threshold current to 5KA / cm 2 , the slope efficiency rises to 0.6W / A, and the continuous working life at room temperature can be increased to 10,000 hours.

7. A semiconductor laser element according to claim 1, characterized in that: The n-type cladding layer, lower waveguide layer, active layer, upper waveguide layer, electron blocking layer, p-type cladding layer and p-type semiconductor include any one or any combination of GaN, AlGaN, InGaN, AlInGaN, AlN, InN, AlInN, SiC, Ga2O3, BN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, AlInAs, AlInP, AlGaP and InGaP.

8. A semiconductor laser element as claimed in claim 1, characterized in that: The substrate includes any one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, sapphire / SiNx, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

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