Nitride semiconductor laser element

Abstract

The invention relates to the technical field of semiconductor photoelectric devices, in particular to a nitride semiconductor laser element which sequentially comprises a substrate, a lower coating layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer and an upper coating layer from bottom to top, and is characterized in that the lower waveguide layer is the lower waveguide layer; the lower waveguide layer is any one or any combination of InGaN, GaN, InN, AlInGaN, an InGaN / GaN superlattice, an InGaN / AlGaN superlattice, an InGaN / AlGaN superlattice, an InGaN / AlInN superlattice and an InGaN / AlInGaN superlattice; the peak rate electric field distribution of the lower waveguide layer is arc-shaped distribution; the peak rate electric field distribution of the lower waveguide layer has a function y = logax (a is greater than 1) curve distribution; the saturated electron drift rate distribution of the lower waveguide layer has arc-shaped distribution; the saturated electron drift rate distribution of the lower waveguide layer has a function y = x-b (b is greater than an odd number of 1) third quadrant curve distribution; the valence band effective state density distribution of the lower waveguide layer has a function y = (cx + 1) / (cx-1) (c > 1) third quadrant curve distribution.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor optoelectronic devices, in particular to a nitride semiconductor laser. Background Art

[0002] Lasers are widely used in laser displays, laser televisions, laser projectors, communications, 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. The main types of lasers are solid, gas, liquid, semiconductor and dye 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. There are significant differences between lasers and nitride semiconductor light-emitting diodes. 1) Lasers are generated by stimulated emission of carriers, with a small half-width at half maximum 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 spontaneously radiated, and the output power of a single light-emitting diode is in the mW level. 2) The operating current density of the laser reaches KA / cm2, which is more than two 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 incoherent light from high energy level to low energy level without any external influence, while the laser radiates by stimulated transition. The energy of the induced photon should be equal to the difference in energy levels of the electron transition, generating completely coherent light of the photon and the induced photon; 4) The principles are different: the light-emitting diode is a diode that generates radiation and recombination light by electron-hole transition to the quantum well or pn junction under the action of external voltage, while the laser needs to meet the lasing conditions 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.

[0003] Nitride semiconductor lasers have the following problems: the refractive index dispersion of the laser, the high-concentration carrier concentration fluctuations affect the refractive index of the active layer, and the confinement factor decreases with increasing wavelength, resulting in a decrease in the mode gain of the laser. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a nitride semiconductor laser, comprising: a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, and an upper cladding layer arranged in sequence from bottom to top; the lower waveguide layer is a refractive index gradient lower waveguide layer, the refractive index of the lower waveguide layer decreases, and the decreasing trend curve has a function y=x -d The curve distribution in the third quadrant of the curve graph, where d is an odd number and d>1.

[0005] Preferably, the lower waveguide layer is any one or any combination of InGaN, GaN, InN, AlInGaN, InGaN / GaN superlattice, InGaN / AlGaN superlattice, InGaN / AlInN superlattice, and InGaN / AlInGaN superlattice; the peak rate electric field distribution of the lower waveguide layer has an arc-shaped distribution.

[0006] Preferably, the peak velocity electric field distribution of the lower waveguide layer has a function y=log a x-curve distribution, where a>1.

[0007] Preferably, the saturated electron drift velocity distribution of the lower waveguide layer has an arc-shaped distribution.

[0008] Preferably, the saturated electron drift velocity distribution of the lower waveguide layer has a function y=x -b (b>1 odd number) third quadrant curve distribution.

[0009] Preferably, the valence band effective state density distribution of the lower waveguide layer has a function y=(c x +1) / (c x -1) Curve distribution in the third quadrant of the curve graph, where c>1.

[0010] Preferably, the longitudinal acoustic velocity distribution of the lower waveguide layer has a function y=e x / x 2 The curve distribution in the second quadrant of the curve graph.

[0011] Preferably, the peak rate electric field distribution, the saturated electron drift rate distribution and the valence band effective state density distribution of the lower waveguide layer have the following relationship: 1<c≤b≤a.

[0012] Preferably, the In element distribution of the lower waveguide layer has a function y=x -g The curve distribution in the third quadrant of the curve graph, wherein g is an odd number and g>1; the In / H element ratio distribution of the lower waveguide layer has a function y=x -h The curve distribution of the third quadrant of the curve graph, wherein h is an odd number and h>1; the In / C element ratio distribution of the lower waveguide layer has a function y=x -j The curve distribution in the third quadrant of the curve graph, wherein j is an odd number and j>1; the In / O element ratio distribution of the lower waveguide layer has a function y=x -k The curve distribution in the third quadrant of the curve graph, where k is an odd number and k>1; where: h≤k≤j≤g.

[0013] Preferably, the active layer is a periodic structure composed of a well layer and a barrier layer, the number of periods is m, wherein 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, and diamond. or any combination thereof, with a thickness of 10 to 150 angstroms; the barrier 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, and diamond, with a thickness of 10 to 200 angstroms.

[0014] Preferably, the lower cladding layer, the upper waveguide layer, the electron blocking layer and the upper cladding 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, BN, and diamond; and the substrate is sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, sapphire / SiN x , sapphire / SiO2 / SiN x Composite substrate, sapphire / SiN x Any one of a / SiO2 composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: a lower waveguide layer with a gradient refractive index is formed through the technical solution, carriers and photons are effectively confined in the active area, the longitudinal diffusion of the light field is controlled and carriers are aggregated, the confinement factor and carrier injection efficiency of the laser are improved, the carrier injection uniformity and injection uniformity of the laser are improved, thereby improving the mode gain and luminous power of the laser and reducing the threshold current. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate the embodiments and, together with the description, serve to explain the principles of the invention. Other embodiments and many of the intended advantages of the embodiments will be readily apparent as they become better understood by reference to the following detailed description. Other features, objects, and advantages of the present application will become more apparent upon reading the detailed description of the non-limiting embodiments made with reference to the following drawings:

[0017] Figure 1 is a schematic structural diagram of a nitride semiconductor laser according to an embodiment of the application;

[0018] Figure 2 is a SIMS secondary ion mass spectrum of a nitride semiconductor laser structure according to one embodiment of the application;

[0019] Figure 3 is a SIMS secondary ion mass spectrum of a nitride semiconductor laser structure according to another embodiment of the application;

[0020] Figure 4 This is a TEM image of an upper cladding layer of a nitride semiconductor laser at a scale of 100 nm according to an embodiment of the application;

[0021] Figure 5 This is a TEM image of an upper waveguide layer of a nitride semiconductor laser at a 100 nm scale according to an embodiment of the application;

[0022] Figure 6 This is a TEM image of an active layer of a nitride semiconductor laser at a 10 nm scale according to an embodiment of the application;

[0023] Figure 7 This is a TEM image of a lower waveguide layer of a nitride semiconductor laser at a scale of 200 nm according to an embodiment of the application;

[0024] Figure 8 This is a TEM image of an electron blocking layer of a nitride semiconductor laser at a 20 nm scale according to an embodiment of the application;

[0025] Figure 9It is a SIMS secondary ion mass spectrum of the structure of a nitride semiconductor laser according to another embodiment of the application.

[0026] The meaning of the numbers in the figure are: 100, substrate; 101, lower cladding layer; 102, lower waveguide layer; 103, active layer; 104, upper waveguide layer; 105, electron blocking layer; 106, upper cladding layer. DETAILED DESCRIPTION

[0027] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the relevant invention are shown in the accompanying drawings.

[0028] like Figures 1 to 8 As shown, this embodiment proposes a nitride semiconductor laser, comprising: a substrate 100, a lower cladding layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, an electron blocking layer 105, and an upper cladding layer 106, which are arranged in order from bottom to top; the refractive index of the lower waveguide layer 102 decreases, and the decreasing trend curve has a function y=x -d The curve distribution in the third quadrant of the curve graph, where d is an odd number and d>1.

[0029] Preferably, the lower waveguide layer 102 is any one or any combination of InGaN, GaN, InN, AlInGaN, InGaN / GaN superlattice, InGaN / AlGaN superlattice, InGaN / AlInN superlattice, and InGaN / AlInGaN superlattice.

[0030] In this embodiment, the refractive index of the lower waveguide layer 102 is designed so that the peak rate electric field distribution of the lower waveguide layer 102 has an arc distribution. More specifically, the peak rate electric field distribution of the lower waveguide layer 102 has a function y=log a x-curve distribution, where a>1.

[0031] Through this design, the saturated electron drift velocity distribution of the lower waveguide layer 102 has an arc-shaped distribution, which is specifically reflected in that the saturated electron drift velocity distribution of the lower waveguide layer 102 has a function y=x -b (b>1 odd number) third quadrant curve distribution.

[0032] By designing the refractive index of the lower waveguide layer 102, in addition to making the peak velocity electric field distribution and saturated electron drift velocity distribution of the lower waveguide layer 102 have the above-mentioned characteristic curves, the valence band effective state density distribution and longitudinal sound velocity distribution of the lower waveguide layer 102 also have certain excellent characteristics. Specifically, the valence band effective state density distribution of the lower waveguide layer 102 has a function y=(c x +1) / (c x -1) The curve distribution in the third quadrant of the curve graph, where c>1; the longitudinal sound velocity distribution of the lower waveguide layer 102 has the function y=e x / x 2 The curve distribution in the second quadrant of the curve graph.

[0033] In addition, in order to better effectively confine carriers and photons within the active region, control the longitudinal diffusion of the light field and aggregate carriers, thereby improving the confinement factor and carrier injection efficiency of the laser, improving the carrier injection uniformity and injection uniformity of the laser, thereby improving the mode gain and luminous power of the laser and reducing the threshold current, the peak rate electric field distribution, saturated electron drift rate distribution and valence band effective state density distribution of the lower waveguide layer 102 are designed to have the following relationship: 1<c≤b≤a.

[0034] Preferably, Figure 9 As shown, the In element distribution of the lower waveguide layer 102 has a function y=x -g The curve distribution in the third quadrant of the curve graph, wherein g is an odd number and g>1; the In / H element ratio distribution of the lower waveguide layer has a function y=x -h The curve distribution of the third quadrant of the curve graph, wherein h is an odd number and h>1; the In / C element ratio distribution of the lower waveguide layer has a function y=x -j The curve distribution in the third quadrant of the curve graph, wherein j is an odd number and j>1; the In / O element ratio distribution of the lower waveguide layer has a function y=x -k The curve distribution in the third quadrant of the curve graph, where k is an odd number and k>1; where: h≤k≤j≤g.

[0035] Specifically, the active layer 103 is a periodic structure composed of a well layer and a barrier layer, the number of periods is m, where 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, AlGaA Any one or any combination of sSb, InGaAsSb, SiC, Ga2O3, BN, diamond, with a thickness of 10 to 150 angstroms; the barrier 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, Ga2O3, BN, diamond, any one or any combination thereof, with a thickness of 10 to 200 angstroms; the lower cladding layer 101, the upper waveguide layer 104, the electron blocking layer 105 and the upper cladding layer 106 are GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, A lGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, diamond, any one or any combination thereof; the substrate 100 is sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, sapphire / SiN x , sapphire / SiO2 / SiN x Composite substrate, sapphire / SiN x Any one of a / SiO2 composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0036] In the first embodiment, if Figure 4As shown, the thickness and composition of each layer in the upper waveguide layer 104, the electron blocking layer 105 and the upper cladding layer 106 of a nitride semiconductor laser element of the present application can be intuitively seen through the TEM image at the 100nm scale; where 2827A is the thickness of the upper cladding layer 106, where A represents the thickness in angstroms.

[0037] In the second embodiment, if Figure 5 As shown, the thickness and composition of each layer in the lower waveguide layer 102, active layer 103, upper waveguide layer 104 and electron blocking layer 105 of a nitride semiconductor laser element of the present application can be intuitively seen through the TEM image at a scale of 100 nm; Figure 5 The thickness of the upper waveguide layer 104 is 2827A. Figure 5 It is clearly reflected in this example that the active layer 103 is a periodic structure consisting of a well layer and a barrier layer, and the well layer and the barrier layer are made of different materials; and the electron blocking layer 105 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.

[0038] In addition, if Figures 6 to 8 These are TEM images of different embodiments at different scales, which allow intuitive observation of the microstructure of each structure in different embodiments under TEM.

[0039] The effects that can be achieved by adopting the technical means of this application are:

[0040] Blue laser project Traditional lasers Laser of the present invention Range of change Limiting Factor 1.50％ 2.91％ 94％ Slope efficiency (W / A) 0.8 1.84 130％ Optical power (W) 4.6 6.7 46％

[0041] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

Claims

1. A nitride semiconductor laser device, characterized in that: include: The substrate, the lower cladding layer, the lower waveguide layer, the active layer, the upper waveguide layer, the electron blocking layer, and the upper cladding layer are sequentially arranged from bottom to top; The lower waveguide layer is a refractive index gradient lower waveguide layer, the refractive index of the lower waveguide layer decreases, and the decreasing trend curve has a function y=x -d The curve distribution in the third quadrant of the curve graph, where d is an odd number and d>1.

2. The nitride semiconductor laser device according to claim 1, wherein: The lower waveguide layer is any one or any combination of InGaN, GaN, InN, AlInGaN, InGaN / GaN superlattice, InGaN / AlGaN superlattice, InGaN / AlInN superlattice, and InGaN / AlInGaN superlattice; the peak rate electric field distribution of the lower waveguide layer has an arc-shaped distribution.

3. The nitride semiconductor laser device according to claim 2, wherein: The peak velocity electric field distribution of the lower waveguide layer has a function y=log a x-curve distribution, where a>1.

4. The nitride semiconductor laser device according to claim 3, wherein: The saturated electron drift velocity distribution of the lower waveguide layer has an arc-shaped distribution.

5. The nitride semiconductor laser device according to claim 4, wherein: The saturated electron drift velocity distribution of the lower waveguide layer has a function y=x -b (b>1 odd number) third quadrant curve distribution.

6. The nitride semiconductor laser device according to claim 5, wherein: The valence band effective state density distribution of the lower waveguide layer has a function y=(c x +1) / (c x -1) Curve distribution in the third quadrant of the curve graph, where c>1.

7. The nitride semiconductor laser device according to claim 1, wherein: The longitudinal acoustic velocity distribution of the lower waveguide layer has a function y=e x / x 2 The curve distribution in the second quadrant of the curve graph.

8. The nitride semiconductor laser device according to claim 6, wherein: The peak rate electric field distribution, saturated electron drift rate distribution and valence band effective state density distribution of the lower waveguide layer have the following relationship: 1<c≤b≤a.

9. The nitride semiconductor laser device according to claim 6, wherein: The In element distribution of the lower waveguide layer has a function y=x -g The curve distribution in the third quadrant of the curve graph, wherein g is an odd number and g>1; the In / H element ratio distribution of the lower waveguide layer has a function y=x -h The curve distribution in the third quadrant of the curve graph, wherein h is an odd number and h>1; the In / C element ratio distribution of the lower waveguide layer has a function y=x -j The curve distribution in the third quadrant of the curve graph, wherein j is an odd number and j>1; the In / O element ratio distribution of the lower waveguide layer has a function y=x -k The curve distribution in the third quadrant of the curve graph, where k is an odd number and k>1; where h≤k≤j≤g.

10. The nitride semiconductor laser device according to claim 1, wherein: The active layer is a periodic structure composed of a well layer and a barrier layer, the number of periods is m, wherein 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, In Any one or any combination of GaAsSb, SiC, Ga2O3, BN, and diamond, with a thickness of 10 to 150 angstroms; the barrier 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, Ga2O3, BN, diamond, any one or any combination thereof, with a thickness of 10 to 200 angstroms; the lower cladding layer, the upper waveguide layer, the electron blocking layer and the upper cladding layer are GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, G Any one or any combination of aSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, diamond; the substrate is sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, sapphire / SiNx, sapphire / SiO2 / SiN x Composite substrate, sapphire / SiN x Any one of a / SiO2 composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

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