Gallium nitride-based semiconductor laser chip with waveguide layer under low oscillation threshold

Abstract

The invention discloses a gallium nitride-based semiconductor laser chip with a low-oscillation-threshold lower waveguide layer, which sequentially comprises a substrate, a lower coating layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper coating layer from bottom to top, and is characterized in that the lower waveguide layer is the low-oscillation-threshold lower waveguide layer; the waveguide layer under the low oscillation threshold is any one or any combination of InGaN, GaN, InN and AlInGaN; and the deformation potential distribution of the waveguide layer under the low oscillation threshold value has broken line type distribution. According to the invention, the deformation potential of the lower waveguide layer and the active layer of the laser is regulated and controlled, the carrier delocalization of the active layer and the lower waveguide layer is reduced, the electron hole injection and transport uniformity is improved, the population inversion is accelerated, and the threshold current density is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor optoelectronic devices, and in particular to a gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer. 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. 1) Lasers are generated by stimulated radiation from carriers, with a small half-width spectrum and high brightness. The output power of a single laser can be in the W level, while nitride semiconductor light-emitting diodes emit spontaneous radiation, and the output power of a single light-emitting diode is in the mW level. 2) The current density of the laser is as high as 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; 3) Light-emitting diodes spontaneously radiate incoherent light from high energy levels to low energy levels without external effects, while lasers radiate stimulated transitions. The energy of induced photons should be equal to the difference in energy levels of electron transitions, generating photons and induced photons that are completely coherent light; 4) Different principles: light-emitting diodes produce radiation recombination and luminescence under the action of external voltage when electron holes transition to quantum wells or pn junctions, while lasers require lasing conditions to be met before they can be lased. The carrier inversion distribution in the active region must be met. The stimulated radiation light oscillates back and forth in the resonant cavity, and the propagation in the gain medium amplifies the light. The threshold condition is met so that the gain is greater than the loss, and finally the laser is output.

[0004] Nitride semiconductor lasers have the following problems: the absorption loss of impurities in the optical waveguide of the violet laser is high, which causes the internal optical loss to increase, resulting in a decrease in the laser slope efficiency and an increase in the threshold current; the electron-hole asymmetry and mismatch in the quantum well are serious, electron leakage and carrier delocalization occur, hole transport in the quantum well is more difficult, carrier injection is uneven, and gain is uneven, which makes the laser gain spectrum wider and the peak gain decrease, resulting in an increase in the laser threshold current; non-radiative recombination losses and free carrier absorption in the active region of the violet laser generate a lot of heat. If the laser has low thermal conductivity, poor heat dissipation, and poor temperature characteristics, it will aggravate the thermal mismatch between the semiconductor epitaxial layers, leading to problems such as an increase in threshold current, a decrease in output optical power and slope efficiency. Summary of the invention

[0005] The present invention proposes a gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer, which regulates the deformation potential of the laser's lower waveguide layer and active layer, reduces carrier delocalization in the active layer and the lower waveguide layer, improves the uniformity of electron-hole injection and transport, accelerates particle number inversion, and reduces threshold current density.

[0006] The present invention provides a gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer, which comprises, from bottom to top, a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper cladding layer, wherein the lower waveguide layer is a low oscillation threshold lower waveguide layer; the low oscillation threshold lower waveguide layer is any one or any combination of InGaN, GaN, InN, and AlInGaN; and the deformation potential distribution of the low oscillation threshold lower waveguide layer has a broken line distribution.

[0007] Preferably, the deformation potential distribution of the waveguide layer at the low oscillation threshold shows a steep upward trend toward the lower cladding layer, and the rising angle is 40 to 90°.

[0008] Preferably, the deformation potential distribution of the waveguide layer under the low oscillation threshold is approximately an inverse "L" type distribution, and the approximate function y=xe x Curved distribution.

[0009] Preferably, the covalent bond energy distribution of the waveguide layer at the low oscillation threshold has a zigzag distribution, showing a steep upward trend toward the lower cladding layer, and the rising angle is 40 to 90°.

[0010] Preferably, the covalent bond energy distribution of the waveguide layer under the low oscillation threshold is approximately an inverse "L" type distribution, and the approximate function y=e x / xThird quadrant curve distribution.

[0011] Preferably, the radiation recombination coefficient distribution of the waveguide layer under the low oscillation threshold is approximately a "7" type distribution, showing a steep downward trend toward the lower cladding layer, with a downward change angle of 50 to 90°, and the approximate function y=ex / xThird quadrant curve distribution.

[0012] Preferably, the photon energy absorption coefficient distribution of the waveguide layer under the low oscillation threshold is approximately an inverse "L" type distribution, showing a steep upward trend toward the lower cladding layer, with an upward change angle of 50 to 90°, and the approximate function y=xe x distributed.

[0013] 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, diamond or the like. Any combination, with a thickness of 10 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 to 200 angstroms.

[0014] Preferably, the lower cladding layer, the upper waveguide 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.

[0015] Preferably, the substrate comprises sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, graphene, 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.

[0016] Compared with the prior art, the gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer provided by the embodiment of the present invention has the following beneficial effects: the present invention regulates the deformation potential of the laser lower waveguide layer and the active layer, reduces the carrier delocalization of the active layer and the lower waveguide layer, improves the uniformity of electron-hole injection and transport, accelerates the population inversion, reduces the threshold current density, and at the same time, reduces the impurity absorption loss of the lower waveguide layer, the heat generated by non-radiative recombination and free carrier absorption, reduces thermal mismatch and changes the doping morphology, regulates the built-in electric field and resistance, accelerates the number of electrons at the bottom of the conduction band in the resonant cavity to far exceed the number of holes at the top of the valence band, accelerates the population inversion of the laser, makes the radiation of the carriers greater than the loss, and the highly degenerate electron-hole recombination laser radiation oscillates and amplifies to generate coherent laser output, thereby improving the slope efficiency and reducing the threshold current of the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer according to an embodiment of the present invention;

[0018] Figure 2 It is a SIMS secondary ion mass spectrum of a gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer according to an embodiment of the present invention;

[0019] Reference numerals: 100: substrate; 101: lower cladding layer; 102: lower waveguide layer; 103: active layer; 104: upper waveguide layer, 105: upper cladding layer. DETAILED DESCRIPTION

[0020] 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.

[0021] In order to solve the above problems, a gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer provided in an embodiment of the present application will be introduced and explained in detail through the following specific embodiments.

[0022] Reference Figure 1-2 The present invention provides a gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer, which includes, from bottom to top, 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. The lower waveguide layer 102 is a low oscillation threshold lower waveguide layer 102; the low oscillation threshold lower waveguide layer 102 is any one or any combination of InGaN, GaN, InN, and AlInGaN; the deformation potential distribution of the low oscillation threshold lower waveguide layer 102 has a broken line distribution.

[0023] In the present invention, the deformation potential distribution of the waveguide layer 102 at the low oscillation threshold presents a steep upward trend toward the lower cladding layer 101, and the rising angle is 40 to 90 degrees. The deformation potential distribution of the waveguide layer 102 at the low oscillation threshold is approximately an inverse "L" type distribution, and the approximate function y=xe x Curved distribution.

[0024] In the present invention, the covalent bond energy distribution of the waveguide layer 102 at the low oscillation threshold has a broken line distribution, showing a steep upward trend toward the lower cladding layer 101, and the rising angle is 40 to 90 degrees. The covalent bond energy distribution of the waveguide layer 102 at the low oscillation threshold is approximately an inverse "L" type distribution, and the approximate function y=e x / xThird quadrant curve distribution.

[0025] In the present invention, the radiation recombination coefficient distribution of the waveguide layer 102 under the low oscillation threshold is approximately a "7" type distribution, and shows a steep downward trend toward the cladding layer 101, with a downward change angle of 50 to 90°, and the approximate function y=e x / xThird quadrant curve distribution.

[0026] In the present invention, the photon energy absorption coefficient distribution of the waveguide layer 102 under the low oscillation threshold is approximately an inverse "L" type distribution, and shows a steep upward trend toward the lower cladding layer 101, with an upward change angle of 50 to 90°, and the approximate function y=xe x distributed.

[0027] The present invention reduces the impurity absorption loss of the lower waveguide layer 102, the heat generated by non-radiative recombination and free carrier absorption, reduces thermal mismatch and changes the doping morphology, regulates the built-in electric field and resistance, accelerates the number of electrons at the bottom of the conduction band in the resonant cavity to far exceed the number of holes at the top of the valence band, accelerates the particle number inversion of the laser, makes the radiation of the carriers greater than the loss, and the highly degenerate electron-hole recombination laser radiation oscillates and amplifies to generate coherent laser output, thereby improving the slope efficiency and reducing the threshold current of the laser; the specific data are shown in the following table:

[0028] UV laser project Conventional laser Laser of the present invention Range of change Slope efficiency (W / A) 1.26 1.97 56％ <![CDATA[Threshold current density (kA / cm 2 )]]> 3.6 1.03 -71％

[0029] 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, BN, and diamond. 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 to 200 angstroms.

[0030] In the present invention, the lower cladding layer 101, the upper waveguide layer 104, and the upper cladding 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, BN, and diamond.

[0031] In the present invention, 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, graphene, 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.

[0032] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer, comprising, from bottom to top, 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), characterized in that: The lower waveguide layer (102) is a low oscillation threshold lower waveguide layer (102); the low oscillation threshold lower waveguide layer (102) is any one or any combination of InGaN, GaN, InN, and AlInGaN; and the deformation potential distribution of the low oscillation threshold lower waveguide layer (102) has a broken line distribution.

2. The gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer according to claim 1, characterized in that: The deformation potential distribution of the waveguide layer (102) at the low oscillation threshold shows a steep upward trend toward the lower cladding layer (101), and the upward change angle is 40 to 90 degrees.

3. The gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer according to claim 2, characterized in that: The deformation potential distribution of the waveguide layer (102) under the low oscillation threshold is approximately an inverse "L" type distribution, and the approximate function y=xe x Curved distribution.

4. The gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer according to claim 1, characterized in that: The covalent bond energy distribution of the waveguide layer (102) at the low oscillation threshold has a broken-line distribution, and presents a steep upward trend toward the lower cladding layer (101), with an upward change angle of 40 to 90 degrees.

5. The gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer according to claim 4, characterized in that: The covalent bond energy distribution of the waveguide layer (102) at the low oscillation threshold is approximately an inverse "L" type distribution, and the approximate function y=e x / xThird quadrant curve distribution.

6. The gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer according to claim 1, characterized in that: The radiation recombination coefficient distribution of the waveguide layer (102) under the low oscillation threshold is approximately a "7" type distribution, and shows a steep downward trend toward the lower cladding layer (101), with a downward change angle of 50 to 90 degrees, and the approximate function y=e x / xThird quadrant curve distribution.

7. The gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer according to claim 1, characterized in that: The photon energy absorption coefficient distribution of the waveguide layer (102) at the low oscillation threshold is approximately an inverse "L" type distribution, and presents a steep upward trend toward the lower cladding layer (101), with an upward change angle of 50 to 90 degrees, and the approximate function y=xe x distributed.

8. The gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer 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, diamond or the like. Any combination, with a thickness of 10 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 to 200 angstroms.

9. The gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer according to claim 1, characterized in that: The lower cladding layer (101), the upper waveguide layer (104), and the upper cladding 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, BN, and diamond.

10. The gallium nitride-based semiconductor laser chip with a low oscillation threshold lower waveguide layer 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, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, graphene, 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.

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