Gallium nitride semiconductor purple light laser

Abstract

The gallium nitride semiconductor purple light laser comprises a substrate, a lower coating layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper coating layer which are sequentially arranged from bottom to top. According to the gallium nitride semiconductor purple light laser, the distribution characteristic of the drift rate of saturated electrons in the lower waveguide layer of the gallium nitride semiconductor purple light laser is specifically designed, so that the lower waveguide layer forms a carrier pinning lower waveguide layer, redundant carriers are limited in an active region under the condition of large injection, electron leakage current is eliminated, the carrier transport and injection efficiency is improved, and the quantum efficiency is improved. The bipolar conductance effect and the junction voltage saturation at the threshold are inhibited, and the series resistance and voltage are reduced; meanwhile, an acceleration hole and an electronic quasi-Fermi level are pinned, and the rate of stimulated radiation exceeding spontaneous radiation is accelerated, so that carriers are completely converted into photons to be output, symmetry breaking corresponding to a far-equilibrium state is inhibited, a deep level trap of a lower waveguide layer is reduced, and the capture effect of a depletion region is enhanced. And the problems of junction voltage jump and series resistor sinking are solved.

Description

Technical Field

[0001] This application relates to the field of semiconductor optoelectronic devices, and particularly to a gallium nitride semiconductor violet laser. Background Art

[0002] Lasers are widely used in the fields of laser display, laser TV, laser projector, communication, medical treatment, weapons, guidance, ranging, spectral analysis, cutting, precision welding, high-density optical storage, etc. There are many types of lasers and various classification methods, mainly including solid-state, gas, liquid, semiconductor, and dye lasers. Compared with other types of lasers, all-solid-state semiconductor lasers have the advantages of small volume, 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 emission of carriers, with a relatively small spectral full width at half maximum, very high brightness, and the output power of a single laser can be in the order of watts, while nitride semiconductor light-emitting diodes are spontaneous emission, and the output power of a single light-emitting diode is in the order of milliwatts;

[0005] 2) The operating current density of lasers 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 severe Auger recombination, stronger polarization effects, and more serious electron-hole mismatch, leading to a more serious efficiency droop effect;

[0006] 3) Light-emitting diodes are spontaneous transition radiation, without external action, incoherent light that transitions from a high energy level to a low energy level, while lasers are stimulated transition radiation, and the induced photon energy should be equal to the energy difference between electron transitions, generating completely identical coherent light of photons and induced photons;

[0007] 4) Different principles: Light-emitting diodes generate radiative recombination luminescence when electrons and holes transition to quantum wells or p-n junctions under the action of an external voltage, while lasers require lasing conditions to be met for lasing. It is necessary to satisfy the inverted distribution of carriers in the active region. The stimulated emission light oscillates back and forth in the resonant cavity, and the propagation in the gain medium amplifies the light. When the threshold condition is met, the gain is greater than the loss, and finally, laser light is output.

[0008] Nitride semiconductor lasers have the following problems: The symmetry breaking corresponding to the phase transition far from equilibrium in violet lasers causes discontinuous or abrupt phenomena at the threshold of the laser, such as sudden increase in conductance, capacitance sinking, sudden increase in junction voltage, sinking of series resistance, sudden increase in ideality factor, etc. When electrons leak into the p-type semiconductor, a bipolar conductance effect is formed. When the carrier concentration in the active layer is saturated, the junction voltage at the threshold is saturated, but the series resistance increases, and the total voltage of the laser rises. Summary of the Invention

[0009] To solve one of the above technical problems, the present invention provides a gallium nitride semiconductor violet laser.

[0010] An embodiment of the present invention provides a gallium nitride semiconductor violet laser, which includes a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper cladding layer arranged in sequence from bottom to top. The lower waveguide layer is a carrier-pinning lower waveguide layer. The carrier-pinning lower waveguide layer has a saturated electron drift velocity distribution characteristic, and the saturated electron drift velocity of the carrier-pinning lower waveguide layer follows a function y1=(e x +e -x ) / (e x -e -x ) curve distribution, where x is the depth of the carrier-pinning lower waveguide layer in the direction of the active layer.

[0011] Preferably, the saturated electron drift velocity of the carrier-pinning lower waveguide layer shows a downward trend in the direction of the lower cladding layer, and the downward angle is 50° to 90°.

[0012] Preferably, the carrier-pinning lower waveguide layer also has a transverse sound velocity distribution characteristic, and the transverse sound velocity of the carrier-pinning lower waveguide layer follows a function y2 = xe x curve distribution.

[0013] Preferably, the transverse sound velocity of the carrier-pinning lower waveguide layer shows an upward trend in the direction of the lower cladding layer, and the upward angle is 50° to 90°.

[0014] Preferably, the carrier-pinning lower waveguide layer also has a bulk modulus distribution characteristic, and the bulk modulus of the carrier-pinning lower waveguide layer follows a function y3 = xe x curve distribution.

[0015] Preferably, the carrier-pinning lower waveguide layer also has a longitudinal sound velocity distribution characteristic, and the longitudinal sound velocity of the carrier-pinning lower waveguide layer follows a function y4 = xe x curve distribution.

[0016] Preferably, the carrier-pinning lower waveguide layer is any one or any combination of InGaN, GaN, InN, and AlInGaN.

[0017] Preferably, the active layer is a periodic structure composed of well layers and barrier layers, where the number of periods satisfies 3≥m≥1. The well 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, BN, diamond, with a thickness of 10 angstroms to 150 angstroms. 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, BN, diamond, with a thickness of 10 angstroms to 200 angstroms.

[0018] Preferably, the lower cladding layer, the upper waveguide layer, and the upper cladding layer are any one or any combination of 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, diamond.

[0019] Preferably, the substrate includes any one of 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 / SiO2 composite substrate, magnesium aluminate spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2, and LiGaO2 composite substrate.

[0020] The beneficial effects of the present invention are as follows: The present invention specifically designs the distribution characteristics of the saturated electron drift rate in the lower waveguide layer of the gallium nitride semiconductor violet laser, so that the lower waveguide layer forms a carrier-pinned lower waveguide layer, realizing that excess carriers are restricted in the active region under large injection conditions, eliminating electron leakage current, improving the carrier transport and injection efficiency, suppressing the bipolar conductivity effect and the saturation of the junction voltage at the threshold, and reducing the series resistance and voltage; at the same time, accelerating the hole and electron quasi-Fermi levels are pinned, accelerating the rate of stimulated emission exceeding spontaneous emission, enabling carriers to be completely converted into photon output, and at the same time, suppressing the symmetry breaking corresponding to the non-equilibrium state, reducing the deep energy level traps in the lower waveguide layer, enhancing the capture effect in the depletion region, and suppressing the problems of the upward jump of the junction voltage and the downward sink of the series resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments and descriptions thereof of the present application are used to explain the present application, and do not constitute an improper limitation of the present application. In the drawings:

[0022] Figure 1 is a schematic structural diagram of the gallium nitride semiconductor violet laser according to an embodiment of the present invention;

[0023] Figure 2 is a SIMS secondary ion mass spectrometry diagram of the gallium nitride semiconductor violet laser according to an embodiment of the present invention;

[0024] Figure 3 is a partial enlarged view of the SIMS secondary ion mass spectrometry diagram of the gallium nitride semiconductor violet laser according to an embodiment of the present invention.

[0025] Reference numerals:

[0026] 100, substrate, 101, lower cladding layer, 102, lower waveguide layer, 103, active layer, 104, upper waveguide layer, 105, upper cladding layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In order to make the technical solutions and advantages in the embodiments of the present application clearer and more understandable, the following further describes the exemplary embodiments of the present application in detail with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0028] As Figures 1 to 3As shown in the figure, this embodiment proposes a gallium nitride semiconductor violet laser, which includes a substrate 100, a lower cladding layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, and an upper cladding layer 105 arranged in sequence from bottom to top. Among them, the lower waveguide layer 102 is a carrier-pinned lower waveguide layer 102.

[0029] Specifically, in this embodiment, the gallium nitride semiconductor violet laser is provided with a substrate 100, a lower cladding layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, and an upper cladding layer 105 in sequence from bottom to top. The lower waveguide layer 102 has a saturated electron drift rate distribution characteristic, which is specifically in the form of a function y1 = (e x +e -x ) / (e x -e -x ) curve distribution, where x is the depth of the carrier-pinned lower waveguide layer 102 in the direction of the active layer 103, similar to a "┓" type distribution, so that the lower waveguide layer 102 forms a carrier-pinned lower waveguide layer 102.

[0030] In this embodiment, the distribution characteristic of the saturated electron drift rate in the lower waveguide layer 102 is specifically designed, so that the lower waveguide layer 102 forms a carrier-pinned lower waveguide layer 102, realizing the confinement of excess carriers in the active region under large injection conditions, eliminating electron leakage current, improving the carrier transport and injection efficiency, suppressing the bipolar conductivity effect and the saturation of the junction voltage at the threshold, reducing the series resistance and voltage; at the same time, accelerating the pinning of the hole and electron quasi-Fermi levels, accelerating the rate of stimulated emission exceeding spontaneous emission, enabling the carriers to be completely converted into photon output, and at the same time, suppressing the symmetry breaking corresponding to the non-equilibrium state, reducing the deep energy level traps in the lower waveguide layer 102, enhancing the capture effect in the depletion region, and suppressing the problems of the jump of the junction voltage and the sinking of the series resistance.

[0031] In some optional embodiments, the saturated electron drift rate of the carrier-pinned lower waveguide layer 102 also shows a certain change trend in the direction of the lower cladding layer 101. Specifically, the saturated electron drift rate of the carrier-pinned lower waveguide layer 102 shows a downward trend in the direction of the lower cladding layer 101, and the downward angle is 50° to 90°.

[0032] In some optional embodiments, the carrier-pinned lower waveguide layer 102 also has a transverse sound velocity distribution characteristic. The transverse sound velocity of the carrier-pinned lower waveguide layer 102 is in the form of a function y2 = xe x curve distribution, showing a broken line type distribution, approximately similar to an inverted "L" type distribution. At the same time, the transverse sound velocity of the carrier-pinned lower waveguide layer 102 also shows a certain change trend in the direction of the lower cladding layer 101. Specifically, the transverse sound velocity of the carrier-pinned lower waveguide layer 102 shows an upward trend in the direction of the lower cladding layer 101, and the upward angle is 50° to 90°.

[0033] In some alternative embodiments, the waveguide layer 102 under carrier pinning further has a characteristic of volume elastic modulus distribution, and the volume elastic modulus of the waveguide layer 102 under carrier pinning is in the function of y3 = xe x Curve distribution, showing a broken-line distribution, approximately similar to an inverted "L" type distribution.

[0034] In some alternative embodiments, the waveguide layer 102 under carrier pinning further has a characteristic of longitudinal sound velocity distribution, and the longitudinal sound velocity of the waveguide layer 102 under carrier pinning is in the function of y4 = xe x Curve distribution, showing a broken-line distribution, approximately similar to an inverted "L" type distribution.

[0035] In this embodiment, by specifically designing the distribution characteristics of the transverse sound velocity, volume elastic modulus, and longitudinal sound velocity of the waveguide layer 102 under carrier pinning, it is possible to further confine the excess carriers in the active region under large injection conditions, eliminate electron leakage current, improve the carrier transport and injection efficiency, suppress the bipolar conductivity effect and the saturation of the junction voltage at the threshold, reduce the series resistance and voltage; at the same time, accelerate the pinning of the hole and electron quasi-Fermi levels, accelerate the rate of stimulated emission exceeding spontaneous emission, completely convert the carriers into photon output, and at the same time, suppress the symmetry breaking corresponding to the non-equilibrium state, reduce the deep energy level traps of the lower waveguide layer 102, enhance the capture effect of the depletion region, and suppress the problems of the jump of the junction voltage and the sink of the series resistance.

[0036] In some alternative embodiments, the waveguide layer 102 under carrier pinning is any one or any combination of InGaN, GaN, InN, and AlInGaN.

[0037] In some optional embodiments, the active layer 103 is a periodic structure composed of well layers and barrier layers, where the number of periods satisfies 3≥m≥1. The well 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, BN, diamond, with a thickness of 10 angstroms to 150 angstroms. 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, BN, diamond, with a thickness of 10 angstroms to 200 angstroms.

[0038] In some optional embodiments, the lower cladding layer 101, the upper waveguide layer 104, and the upper cladding layer 105 are any one or any combination of 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, diamond.

[0039] In some optional embodiments, the substrate 100 includes 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 xAny one of / SiO2 composite substrates, magnesium aluminate spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrates.

[0040] Obviously, those skilled in the art can make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalent technologies, this application is also intended to include these modifications and variations.

Claims

1. A gallium nitride semiconductor violet laser, comprising a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper cladding layer arranged in sequence from bottom to top, characterized in that: The lower waveguide layer is a carrier pinned lower waveguide layer, and the carrier pinned lower waveguide layer has a saturated electron drift rate distribution characteristic. The saturated electron drift rate of the carrier pinned lower waveguide layer is a function y1=(e x +e -x ) / (e x -e -x ) curve distribution, x is the depth of the waveguide layer toward the active layer under carrier pinning.

2. The gallium nitride semiconductor violet laser according to claim 1, characterized in that: The saturated electron drift velocity of the waveguide layer under carrier pinning shows a decreasing trend toward the lower cladding layer, and the decreasing angle is 50° to 90°.

3. The gallium nitride semiconductor violet laser according to claim 1, characterized in that: The carrier pinned lower waveguide layer also has a transverse sound velocity distribution characteristic, and the transverse sound velocity of the carrier pinned lower waveguide layer is a function y2=xe x Curved distribution.

4. The gallium nitride semiconductor violet laser according to claim 3, characterized in that: The transverse sound velocity of the waveguide layer under carrier pinning increases toward the lower cladding layer, and the rising angle is 50° to 90°.

5. The gallium nitride semiconductor violet laser according to claim 1, characterized in that: The carrier pinned lower waveguide layer also has a bulk elastic modulus distribution characteristic. The bulk elastic modulus of the carrier pinned lower waveguide layer is a function y3=xe x Curved distribution.

6. The gallium nitride semiconductor violet laser according to claim 1, characterized in that: The carrier pinned lower waveguide layer also has a longitudinal sound velocity distribution characteristic, and the longitudinal sound velocity of the carrier pinned lower waveguide layer is a function y4=xe x Curved distribution.

7. The gallium nitride semiconductor violet laser according to claim 1, characterized in that: The carrier pinning lower waveguide layer is any one or any combination of InGaN, GaN, InN and AlInGaN.

8. The gallium nitride semiconductor violet laser according to claim 1, characterized in that: 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 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 , with a thickness of 10 angstroms to 150 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, BN, and diamond, with a thickness of 10 angstroms to 200 angstroms.

9. The gallium nitride semiconductor violet laser according to claim 1, characterized in that: The lower cladding layer, upper waveguide layer and 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.

10. The gallium nitride semiconductor violet laser according to claim 1, characterized in that: The substrate includes 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.

Images