Semiconductor green laser

Abstract

Embodiments of the present description provide a semiconductor green laser. The semiconductor green laser successively comprises, from bottom to top, a substrate (100), a lower confinement layer (101), a lower waveguide layer (102), an active layer (103), an upper waveguide layer (104), and an upper confinement layer (105). The active layer (103) is a quantum well consisting of a well layer and a barrier layer, the period of the quantum well is z, and z is greater than or equal to 1 and less than or equal to 3; the well layer comprises any one or any combination of aluminum indium gallium nitride (AlInGaN), aluminum indium nitrogen (AlInN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), indium nitride (InN), indium gallium nitrogen (InGaN), and gallium nitride (GaN), the thickness of the well layer is p, and p is greater than or equal to 5 angstroms and less than or equal to 100 angstroms; the barrier layer comprises any one or any combination of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN, and GaN, the thickness of the barrier layer is q, and q is greater than or equal to 10 angstroms and less than or equal to 200 angstroms; and the electron effective mass of the well layer is smaller than that of the barrier layer, the spontaneous polarization coefficient of the well layer is smaller than that of the barrier layer, and the band gap of the well layer is smaller than that of the barrier layer.

Description

A semiconductor green laser

[0001] Cross-references

[0002] This specification claims priority to Chinese patent application No. 202311387385.7 filed on October 25, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This specification relates to the technical field of semiconductor optoelectronic devices, and in particular to a semiconductor green laser. Background Art

[0004] Lasers are widely used in laser displays, laser televisions, laser projectors, communications, medical treatment, weaponry, guidance, rangefinders, spectral analysis, cutting, precision welding, high-density optical storage, and other fields. There are many different types of lasers, classified in various ways, including solid-state, gas, liquid, semiconductor, and dye lasers. Compared with other types of lasers, all-solid-state semiconductor lasers offer advantages such as small size, high efficiency, light weight, excellent stability, long life, simple and compact structure, and miniaturization.

[0005] There are major differences between lasers and nitride semiconductor light-emitting diodes:

[0006] (1) Laser is generated by stimulated radiation of carriers, with a small spectral half-width 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.

[0007] (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, and more serious electron-hole mismatch, leading to a more serious efficiency attenuation Droop effect.

[0008] (3) The spontaneous transition radiation of the light-emitting diode is incoherent light that transitions from a high energy level to a low energy level without any external influence, while the laser is stimulated transition radiation. The energy of the induced photon should be equal to the difference in the energy levels of the electron transition, and the photon and the induced photon are completely coherent light.

[0009] (4) Different principles: When an external voltage is applied to a light-emitting diode, electrons and holes jump to the active layer or pn junction to generate radiative recombination and luminescence, while a laser requires that the lasing conditions be met before it can be lased. The carrier distribution in the active region must be inverted, and the stimulated radiation light oscillates back and forth in the resonant cavity. The propagation in the gain medium amplifies the light, and the threshold condition is met so that the gain is greater than the loss, and finally the laser is output.

[0010] Nitride semiconductor lasers have the following problems:

[0011] (1) The Mg acceptor activation energy of p-type semiconductors is large, the ionization efficiency is low, the hole concentration is much lower than the electron concentration, the hole mobility is much lower than the electron mobility, and the quantum well polarization electric field increases the hole injection barrier, causing holes to overflow the active layer. The uneven hole injection and low efficiency lead to serious electron-hole asymmetry mismatch in the quantum well, electron leakage and carrier delocalization, making hole transport more difficult in the quantum well, uneven carrier injection, and uneven gain. At the same time, the laser gain spectrum becomes wider and the peak gain decreases, resulting in an increase in the laser threshold current and a decrease in slope efficiency.

[0012] (2) The increase of In content in quantum well will produce In content fluctuation and strain, broaden the laser gain spectrum, and reduce the peak gain; InN bond energy is low, and high In content InGaN requires a lower temperature during the growth process to ensure In incorporation. However, under low temperature growth conditions, the atomic mobility is low, the low temperature NH3 decomposition efficiency is low, and the mutual solubility gap between InN and GaN is large, resulting in high defect density inside the active layer, InN phase separation and segregation, thermal degradation, composition fluctuation, and unsatisfactory crystal quality, which leads to unsatisfactory quantum well quality and interface quality, causing non-uniform broadening of the laser spectrum, increasing non-radiative recombination centers or optical catastrophes. The increase of In content in quantum well will cause poor thermal stability, and the growth of high temperature p-type semiconductor and confinement layer will cause thermal degradation and lattice mismatch in the active layer, reducing the quality of the active layer and interface quality, reducing radiation efficiency and shortening laser life; especially for green lasers with high In content, the InN phase separation, segregation and composition fluctuation in the active layer are more serious, and the crystal quality and interface quality are even more unsatisfactory.

[0013] (3) The lattice mismatch and large strain of the active layer induce a strong piezoelectric polarization effect, resulting in a strong quantum confined Stark effect (QCSE). The step difference of the laser valence band increases, the injection and transport of holes in the quantum well become more difficult, the probability of electron-hole wave function overlap decreases, the carrier injection is uneven, the gain is uneven, and the peak gain decreases, resulting in an increase in the laser threshold current and a decrease in the slope efficiency, which limits the improvement of the laser's electro-lasing gain.

[0014] (4) Increasing the thickness of the lower confinement layer can reduce the refractive index of the confinement layer, but increasing the thickness of the lower confinement layer will limit the range of component control, which may easily cause problems such as cracking, bending, and quality degradation. At the same time, the light field is dissipated, and the light field mode leaks to the substrate to form standing waves, which will lead to low substrate mode suppression efficiency and poor far-field image FFP quality.

[0015] (5) The laser uses a large current, and the high current density generates a lot of heat. In addition, the device has poor heat dissipation and poor temperature characteristics, which will aggravate the thermal mismatch between the semiconductor epitaxial layers, leading to problems such as increased threshold current, decreased output optical power and slope efficiency.

[0016] (6) Thermal loss: The Stokes shift loss caused by the photon energy difference between the pump light and the oscillating light is converted into heat, and the energy loss caused by the coupling rate from the pump energy level to the laser upper energy level is not 1 is converted into heat. The two together generate a large amount of waste heat, which makes the temperature distribution of the laser uneven, causing uneven distribution of thermal expansion and thermal stress, resulting in temperature quenching, laser breakage, thermal lens effect and stress birefringence effect; the thermal lens produces a lens-like phenomenon in space, and the stress birefringence effect changes the polarization state of the incident light, causing the laser beam to be depolarized and distorted.

[0017] Therefore, it is desired to provide a semiconductor green laser that can effectively make up for the deficiencies of the above technologies.

[0018] Summary of the Invention

[0019] One or more embodiments of this specification provide a semiconductor green laser, which includes, from bottom to top, a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper confinement layer. The active layer is a quantum well composed of a well layer and a barrier layer, and the quantum well period is z, 1≤z≤3; the well layer includes any one or any combination of aluminum indium gallium nitride (AlInGaN), aluminum indium nitride (AlInN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), indium nitride (InN), indium gallium nitride (InGaN) and gallium nitride (GaN), and the thickness of the well layer is p, 5 angstroms≤p≤100 angstroms; the barrier layer includes any one or any combination of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN and GaN, and the thickness of the barrier layer is q, 10 angstroms≤q≤200 angstroms; the electron effective mass of the well layer is smaller than the electron effective mass of the barrier layer, the spontaneous polarization coefficient of the well layer is smaller than the spontaneous polarization coefficient of the barrier layer, and the band gap width of the well layer is smaller than the band gap width of the barrier layer.

[0020] In some embodiments, the active layer includes a first active layer and a second active layer; the electron effective mass of the first active layer has an inverted U-shaped distribution; the electron effective mass of the second active layer has a W-shaped distribution; the spontaneous polarization coefficient of the first active layer has an inverted U-shaped distribution; the spontaneous polarization coefficient of the second active layer has a W-shaped distribution; the band gap width of the first active layer has an inverted U-shaped distribution; the band gap width of the second active layer has a W-shaped distribution.

[0021] In some embodiments, the electron effective mass distribution of the first active layer has a curve distribution of a first function, and the first function is y=Ax 2 +Bx+C(A<0); the spontaneous polarization coefficient distribution of the first active layer has a curve distribution of a second function, and the second function is y=Dx 2+Ex+F(D<0); the band gap width distribution of the first active layer has a curve distribution of a third function, and the third function is y=Jx 2 +Kx+K(J<0); wherein, -500<A≤J≤D<0, and A, B, C, D, E, F, J, and K are constants.

[0022] In some embodiments, the electron effective mass of the second active layer has a curve distribution of a fourth function, and the fourth function is y=Lcos(Mx+N); the spontaneous polarization coefficient of the second active layer has a curve distribution of a fifth function, and the fifth function is y=Pcos(Qx+O); the band gap width of the second active layer has a curve distribution of a sixth function, and the sixth function is y=Rcos(Sx+T); wherein P≤R≤L, L, M, N, P, Q, O, R, S, and T are constants.

[0023] In some embodiments, the electron effective mass of the first active layer is a, the electron effective mass of the well layer of the second active layer is b, and the electron effective mass of the barrier layer of the second active layer is c, wherein 0.05m e ≤b≤c≤a≤0.2m e The spontaneous polarization coefficient of the first active layer is d, the spontaneous polarization coefficient of the well layer of the second active layer is e, and the spontaneous polarization coefficient of the barrier layer of the second active layer is f, wherein -0.05C / m 2 ≤e≤f≤d≤-0.02C / m 2 The bandgap width of the first active layer is g, the bandgap width of the well layer of the second active layer is h, and the bandgap width of the barrier layer of the second active layer is i, wherein 0.5eV≤h≤i≤g≤3.5eV.

[0024] In some embodiments, the element concentration ratio In / Al of the first active layer has a U-shaped distribution; the element concentration ratio In / Al of the second active layer has an M-shaped distribution; the element concentration ratio Si / H of the first active layer has an inverted U-shaped distribution, and the element concentration ratio Si / H of the second active layer has a linear distribution.

[0025] In some embodiments, the element concentration ratio In / Al of the first active layer is 10-100, the element concentration ratio In / Al of the second active layer is 1E4-5E5, and the element concentration ratio In / Al of the second active layer to the first active layer is 1E3-5E4.

[0026] In some embodiments, an In element intensity decrease angle from the second active layer toward the first active layer is α: 45°≤α≤90°, an In element intensity decrease angle from the lower waveguide layer toward the first active layer is β: 45°≤β≤90°, an element concentration ratio In / Al decrease angle from the second active layer toward the first active layer is γ: 35°≤γ≤90°, and an element concentration ratio In / Al decrease angle from the lower waveguide layer toward the first active layer is θ: 35°≤θ≤90°, wherein 35°≤γ≤θ≤α≤β≤90°.

[0027] In some embodiments, the lower confinement layer is any one or any combination of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN and GaN; the lower confinement layer has a first lower confinement layer, a second lower confinement layer, a third lower confinement layer, a fourth lower confinement layer and a fifth lower confinement layer.

[0028] In some embodiments, the thermal expansion coefficient of the first lower confinement layer is a1, the thermal expansion coefficient of the second lower confinement layer is a2, the thermal expansion coefficient of the third lower confinement layer is a3, the thermal expansion coefficient of the fourth lower confinement layer is a4, the thermal expansion coefficient of the fifth lower confinement layer is a5, the thermal expansion coefficient of the lower waveguide layer is b, the thermal expansion coefficient of the active layer is c, the thermal expansion coefficient of the upper waveguide layer is d, and the thermal expansion coefficient of the upper confinement layer is f; the thermal expansion coefficient gradient of the semiconductor green laser has the following relationship: 2.5(10 -6 / K)≤c≤d≤a3≤b≤a5≤a1≤f≤a2≤a4≤6.5(10 -6 / K).

[0029] In some embodiments, the dielectric constant of the first lower confinement layer is g1, the dielectric constant of the second lower confinement layer is g2, the dielectric constant of the third lower confinement layer is g3, the dielectric constant of the fourth lower confinement layer is g4, the dielectric constant of the fifth lower confinement layer is g5, the dielectric constant of the lower waveguide layer is h, the dielectric constant of the active layer is i, the dielectric constant of the upper waveguide layer is j, and the dielectric constant of the upper confinement layer is k; the dielectric constant gradient of the semiconductor green laser has the following relationship: 8≤g4≤g2≤k≤g1≤g5≤h≤g3≤j≤i≤12.

[0030] In some embodiments, the elastic coefficient C33 of the first lower confinement layer is s1, the elastic coefficient C33 of the second lower confinement layer is s2, the elastic coefficient C33 of the third lower confinement layer is s3, the elastic coefficient C33 of the fourth lower confinement layer is s4, and the elastic coefficient C33 of the fifth lower confinement layer is s5. The elastic coefficient C33 of the lower waveguide layer is t, the elastic coefficient C33 of the active layer is u, the elastic coefficient C33 of the upper waveguide layer is v, and the elastic coefficient C33 of the upper confinement layer is w. The elastic coefficient C33 gradient of the semiconductor green laser has the following relationship: 200 GPa≤u≤v≤s3≤t≤s4≤s2≤w≤s1≤s5≤450 GPa.

[0031] In some embodiments, the thermal expansion coefficient of the third lower confinement layer has a curve distribution of a seventh function, the seventh function is y=x / sinx, the elastic coefficient of the third lower confinement layer has a curve distribution of an eighth function, the eighth function is y=x / sinx, and the dielectric constant of the third lower confinement layer has a curve distribution of a ninth function, the ninth function is y=Vx 2 +Ux+W(V<0), where V, U, and W are constants.

[0032] In some embodiments, the lower waveguide layer includes any one or any combination of AlInGaN, AlInN, AlGaN, InGaN, InN and GaN, and the thickness of the lower waveguide layer is 10 angstroms to 9000 angstroms; the upper waveguide layer includes any one or any combination of AlInGaN, AlInN, AlGaN, InGaN, InN and GaN, and the thickness of the upper waveguide layer is 10 angstroms to 9000 angstroms; the upper confinement layer includes any one or any combination of AlInGaN, AlInN, AlN, AlGaN, InGaN and GaN, and the thickness of the upper confinement layer is 10 angstroms to 8000 angstroms; The lower confinement layer includes any one of AlInGaN, AlInN, AlN, AlGaN and GaN, or any combination thereof, and the thickness of the lower confinement layer is 10 angstroms to 90,000 angstroms; the substrate includes any one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, Mo, TiW, Cu, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, diamond, sapphire / SiNx, sapphire / SiNx / SiO2 composite substrate, sapphire / SiO2 / SiNx composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0033] Advantages of one or more embodiments of this specification include:

[0034] The active layer of the embodiment of this specification is a periodic structure composed of a well layer and a barrier layer. The effective mass of electrons in the well layer of the active layer is smaller than the effective mass of electrons in the barrier layer, the spontaneous polarization coefficient of the well layer is smaller than the spontaneous polarization coefficient of the barrier layer, and the band gap width of the well layer is smaller than the band gap width of the barrier layer; the In / Al element ratio of the first active layer has a U-shaped distribution; the In / Al element ratio of the second active layer has an M-shaped distribution, thereby reducing the hole injection barrier, improving the efficiency of hole injection into the active layer, and improving the carrier localization effect, enhancing the electron-hole recombination efficiency of the active layer, and at the same time, suppressing the InN phase separation, segregation and composition fluctuation of the high In component green laser, improving the crystal quality and interface quality of the active layer, reducing defects and non-radiative recombination centers, and improving the slope efficiency of the green laser.

[0035] The embodiments of this specification suppress and alleviate the quantum confined Stark effect, reduce the piezoelectric polarization effect, reduce the band tilt of the active layer, reduce the valence band step, improve the efficiency and transport capacity of hole injection into the active layer, improve the carrier uniformity and laser lasing gain uniformity of the laser, and improve the optical power, lasing gain and slope efficiency of the laser.

[0036] The lower limiting layer in the embodiment of this specification has a thermal expansion coefficient gradient, a dielectric constant gradient and an elastic coefficient C33 gradient; the thermal expansion coefficient gradient and the elastic coefficient gradient design can improve the uniformity of the laser temperature distribution, reduce the uniformity of the thermal expansion coefficient and the thermal stress distribution, inhibit temperature quenching, laser breakage, thermal lens effect and stress birefringence effect, improve the depolarization and distortion of the laser beam, improve the laser beam quality factor and improve the focus spot resolution; the dielectric constant gradient and the elastic coefficient gradient can improve thermal mismatch, reduce the threshold current, increase the output light power and slope efficiency, and at the same time, improve the light field dissipation problem, inhibit the light field mode from leaking to the substrate, and improve the far-field FFP image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] This specification will be further described in the form of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting, and in these embodiments, the same numbers represent the same structures, wherein:

[0038] FIG1 is a schematic structural diagram of a semiconductor green laser according to some embodiments of this specification;

[0039] FIG2 is a SIMS secondary ion mass spectrum diagram of a semiconductor green laser structure according to some embodiments of this specification;

[0040] FIG3 is a SIMS secondary ion mass spectrum diagram of a semiconductor green laser structure according to some embodiments of this specification;

[0041] FIG4 is a TEM lens electron microscope image of an active layer of a semiconductor green laser according to some embodiments of this specification;

[0042] FIG5 is a TEM lens electron microscope image of an upper waveguide layer of a semiconductor green laser according to some embodiments of this specification;

[0043] FIG6 is a TEM lens electron microscope image of an upper confinement layer of a semiconductor green laser according to some embodiments of this specification;

[0044] FIG7 is a SIMS secondary ion mass spectrum of a semiconductor laser according to some embodiments of the present specification (with the change of the marking angle);

[0045] FIG8 is a SIMS secondary ion mass spectrum of a lower confinement layer structure of a semiconductor green laser according to some embodiments of this specification;

[0046] FIG9 is a TEM lens electron microscope image of a lower confinement layer of a semiconductor green laser according to some embodiments of this specification.

[0047] Reference numerals: 100: substrate; 101: lower confinement layer, 102: lower waveguide layer; 103: active layer, 103a: first active layer, 103b: second active layer; 104: upper waveguide layer, 105: upper confinement layer. DETAILED DESCRIPTION

[0048] To more clearly illustrate the technical solutions of the embodiments of this specification, the following briefly describes the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this specification. Those skilled in the art can apply this specification to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0049] It should be understood that the terms "system," "device," "unit," and / or "module" used herein are a method for distinguishing different components, elements, parts, portions, or assemblies at different levels. However, if other terms can achieve the same purpose, the terms may be replaced by other expressions.

[0050] As used in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not refer to the singular but also include the plural. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0051] Flowcharts are used throughout this specification to illustrate the operations performed by systems according to embodiments of this specification. It should be understood that preceding or following operations do not necessarily need to be performed in exact order. Instead, the steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0052] FIG1 is a schematic structural diagram of a semiconductor green laser according to some embodiments of this specification.

[0053] In some embodiments, the semiconductor green laser may include, from bottom to top, a substrate 100 , a lower confinement layer 101 , a lower waveguide layer 102 , an active layer 103 , an upper waveguide layer 104 and an upper confinement layer 105 .

[0054] In some embodiments, the lower confinement layer 101 is fabricated on the substrate 100 , the lower waveguide layer 102 is fabricated on the lower confinement layer 101 , the active layer 103 is fabricated on the lower waveguide layer 102 , the upper waveguide layer 104 is fabricated on the active layer 103 , and the upper confinement layer 105 is fabricated on the upper waveguide layer 104 .

[0055] Substrate 100 is the main base of the laser and is used to grow the various layers of materials for the semiconductor laser. In some embodiments, substrate 100 may include a semiconductor substrate or a composite substrate. In some embodiments, substrate 100 may include any one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, Mo, TiW, Cu, a sapphire / SiO2 composite substrate, a sapphire / AlN composite substrate, diamond, sapphire / SiNx, sapphire / SiNx / SiO2 composite substrate, sapphire / SiO2 / SiNx composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2, and LiGaO2 composite substrates. For example, the material of substrate 100 may be silicon.

[0056] Lower confinement layer 101 and upper confinement layer 105 are used to effectively hinder the diffusion and drift of electrons and limit the expansion of the transverse mode of the optical field into the confinement layer, thereby reducing light loss, that is, lowering the potential barrier and reducing voltage loss. In some embodiments, lower confinement layer 101 can include any one or any combination of AlInGaN, AlInN, AlN, AlGaN, and GaN, and the thickness of lower confinement layer 101 is 10 angstroms to 90,000 angstroms. For example, the thickness of lower confinement layer 101 is 10 angstroms, 100 angstroms, 10000 angstroms, 90,000 angstroms, etc.

[0057] In some embodiments, the upper confinement layer 105 may include any one or any combination of AlInGaN, AlInN, AlN, AlGaN, InGaN, and GaN, and the thickness of the upper confinement layer 105 is 10 angstroms to 8000 angstroms. For example, the thickness of the upper confinement layer 105 is 10 angstroms, 100 angstroms, 1000 angstroms, 8000 angstroms, etc. The materials of the upper confinement layer 105 and the lower confinement layer 101 can be the same or different. For example, the materials of the upper confinement layer 105 and the lower confinement layer 101 are both GaN.

[0058] The lower waveguide layer 102 and the upper waveguide layer 104 have a high refractive index, allowing the light field to partially extend from the main waveguide into the waveguide layer, thereby expanding the near-field spot and reducing the far-field divergence angle of the laser. In some embodiments, the lower waveguide layer 102 can include any one or any combination of AlInGaN, AlInN, AlGaN, InGaN, InN, and GaN. The thickness of the lower waveguide layer 102 ranges from 10 angstroms to 9000 angstroms. For example, the thickness of the lower waveguide layer 102 is 10 angstroms, 100 angstroms, 1000 angstroms, 9000 angstroms, etc.

[0059] In some embodiments, the upper waveguide layer 104 may include any one or any combination of AlInGaN, AlInN, AlGaN, InGaN, InN, and GaN. The thickness of the upper waveguide layer 104 ranges from 10 angstroms to 9000 angstroms. For example, the thickness of the upper waveguide layer 104 is 10 angstroms, 100 angstroms, 1000 angstroms, 9000 angstroms, etc. The materials of the lower waveguide layer 102 and the upper waveguide layer 104 may be the same or different. For example, the materials of the lower waveguide layer 102 and the upper waveguide layer 104 may both be InN.

[0060] In the embodiments of this specification, the laser is constructed by selecting substrate 100, lower confinement layer 101, lower waveguide layer 102, upper waveguide layer 104, and upper confinement layer 105 of suitable materials, and limiting the thickness of each layer within a certain range, thereby ensuring the quality of the laser to a certain extent.

[0061] Figure 5 shows a transmission electron microscope (TEM) image of the upper waveguide layer according to some embodiments of this specification, with a resolution of 100 nm. Figure 6 shows a TEM image of the upper confinement layer according to some embodiments of this specification, with a resolution of 200 nm.

[0062] The active layer 103 is the light-emitting area of ​​the laser. The electrons and holes that enter the active layer are confined in the active layer due to the action of the heterojunction potential barrier, forming a population inversion distribution. These electrons with a population inversion distribution in the active layer can generate spontaneous radiation light when they recombine with holes through transitions.

[0063] In some embodiments, the active layer 103 is a quantum well composed of well layers and barrier layers. A quantum well is a potential well with discrete energy values ​​that can confine particles moving freely in three-dimensional space to a planar region. A semiconductor quantum well structure refers to a composite structure formed by alternating two semiconductor materials. The period of the quantum well is the number of quantum well structures and can be expressed as z, where 1≤z≤3. As an example only, the period z of the quantum well can be 1, in which case the active layer 103 is a single quantum well structure; the period z of the quantum well can be 2 or 3, in which case the active layer 103 is a multiple quantum well structure. Quantum wells can be arranged in a periodic arrangement of alternating well layers and barrier layers. Under the action of an external electric field, electrons in the quantum well transition from a low-energy band material (e.g., barrier layers) to a high-energy band material (e.g., well layers), simultaneously releasing energy that is converted into photons, thereby generating laser light.

[0064] In some embodiments, the well layer of the active layer 103 may include any one or any combination of aluminum indium gallium nitride (AlInGaN), aluminum indium nitride (AlInN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), indium nitride (InN), indium gallium nitride (InGaN), and gallium nitride (GaN). For example, the material of the well layer of the active layer 103 may be AlInGaN.

[0065] In some embodiments, the barrier layer of the active layer 103 may also include any one or any combination of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN and GaN. For example, the barrier layer of the active layer 103 may be made of AlGaN.

[0066] In some embodiments, there may be differences in parameters between the well layer and the barrier layer, such as thickness, electron effective mass, spontaneous polarization coefficient, band gap, and other parameters.

[0067] The thickness of the well layer and barrier layer of a quantum well affects the performance of the laser. The thickness of the well layer can be expressed as p, and the thickness of the barrier layer can be expressed as q. In some embodiments, 5 angstroms ≤ p ≤ 100 angstroms, and 10 angstroms ≤ q ≤ 200 angstroms. For example, the thickness of the well layer, p, can be 5 angstroms, 10 angstroms, 20 angstroms, 100 angstroms, and so on, and the thickness of the barrier layer, q, can be 5 angstroms, 10 angstroms, 20 angstroms, 100 angstroms, and so on.

[0068] In some embodiments, the electron effective mass of the well layer of the active layer 103 is smaller than the electron effective mass of the barrier layer, the spontaneous polarization coefficient of the well layer is smaller than the spontaneous polarization coefficient of the barrier layer, and the band gap width of the well layer is smaller than the band gap width of the barrier layer.

[0069] The effective mass of an electron is a physical quantity used to describe the behavior of electrons in semiconductors under the action of external forces. The effective mass of an electron is an important basic parameter that affects the measurable properties of solids. Spontaneous polarization is the phenomenon in which the centers of positive and negative charges in certain regions within a crystal do not coincide, exhibiting an electric dipole moment, when there is no external electric field. The spontaneous polarization coefficient can be used to measure the degree of spontaneous polarization. The band gap refers to the width of a band gap. In order for a bound electron to become a free electron or a hole, it must obtain enough energy to transition from the valence band to the conduction band. The minimum value of this energy is the band gap. The energy band where free electrons exist is called the conduction band, and the energy band where free holes exist is called the valence band. Both the valence band and the conduction band are conductive.

[0070] In the embodiment of this specification, the active layer 103 is a periodic structure composed of a well layer and a barrier layer. The effective mass of the electrons in the well layer of the active layer 103 is smaller than the effective mass of the electrons in the barrier layer, the spontaneous polarization coefficient of the well layer is smaller than the spontaneous polarization coefficient of the barrier layer, and the band gap width of the well layer is smaller than the band gap width of the barrier layer. This can suppress and alleviate the quantum confined Stark effect, reduce the piezoelectric polarization effect, reduce the energy band tilt of the active layer, reduce the valence band order, improve the efficiency and transport capacity of hole injection into the active layer, improve the carrier uniformity and laser lasing gain uniformity of the laser, and improve the optical power, lasing gain and slope efficiency of the laser.

[0071] In some embodiments, the active layer 103 may include a first active layer 103 a and a second active layer 103 b , and the period of the quantum well is 2.

[0072] FIG4 shows a TEM image of the active layer described in some embodiments of this specification, with a resolution of 20 nm. FIG4 shows that the active layer 103 between the upper waveguide layer 104 and the lower waveguide layer 102 comprises, from top to bottom, a barrier layer of the second active layer 103 b, a well layer of the second active layer 103 b, a barrier layer of the first active layer 103 a, and a well layer of the first active layer 103 a.

[0073] In some embodiments, the electron effective mass of the first active layer 103a has an inverted U-shaped distribution; the electron effective mass of the second active layer 103b has a W-shaped distribution; the spontaneous polarization coefficient of the first active layer 103a has an inverted U-shaped distribution; the spontaneous polarization coefficient of the second active layer 103b has a W-shaped distribution; the bandgap width of the first active layer 103a has an inverted U-shaped distribution; and the bandgap width of the second active layer 103b has a W-shaped distribution.

[0074] In some embodiments, the electron effective mass distribution of the first active layer 103a has a curve distribution of a first function, where the first function is y=Ax 2 +Bx+C(A<0); The spontaneous polarization coefficient distribution of the first active layer 103a has a curve distribution of the second function, and the second function is y=Dx2 +Ex+F(D<0); The band gap width distribution of the first active layer 103a has a curve distribution of the third function, and the third function is y=Jx 2 +Kx+K(J<0); where, -500<A≤J≤D<0, A, B, C, D, E, F, J, K are all constants, and x is a variable.

[0075] In some embodiments, the effective mass of electrons in the second active layer 103b has a curve distribution of a fourth function, which is y=Lcos(Mx+N); the spontaneous polarization coefficient of the second active layer 103b has a curve distribution of a fifth function, which is y=Pcos(Qx+O); the bandgap width of the second active layer 103b has a curve distribution of a sixth function, which is y=Rcos(Sx+T); wherein P≤R≤L, x is a variable, and L, M, N, P, Q, O, R, S, and T are all constants.

[0076] In some embodiments, the electron effective mass of the first active layer 103a is a, the electron effective mass of the well layer of the second active layer 103b is b, and the electron effective mass of the barrier layer of the second active layer 103b is c, wherein 0.05m e ≤b≤c≤a≤0.2m e The spontaneous polarization coefficient of the first active layer 103a is d, the spontaneous polarization coefficient of the well layer of the second active layer 103b is e, and the spontaneous polarization coefficient of the barrier layer of the second active layer 103b is f, wherein -0.05C / m 2 ≤e≤f≤d≤-0.02C / m 2 The bandgap width of the first active layer 103a is g, the bandgap width of the well layer of the second active layer 103b is h, and the bandgap width of the barrier layer of the second active layer 103b is i, wherein 0.5eV≤h≤i≤g≤3.5eV. For example, a is 0.15m e , c is 0.10m e , b is 0.05m e d is -0.02C / m 2 , e is -0.04C / m 2 、f is -0.03C / m 2 , g is 3.5eV, h is 0.5eV, and i is 1.5eV.

[0077] In some embodiments, the active layer 103 includes a first active layer 103a and a second active layer 103b, and the element concentration ratio In / Al of the first active layer 103a has a U-shaped distribution; the element concentration ratio In / Al of the second active layer 103b has an M-shaped distribution; the element concentration ratio Si / H of the first active layer 103a has an inverted U-shaped distribution, and the element concentration ratio Si / H of the second active layer 103b has a linear distribution.

[0078] In the embodiment of the present specification, the element concentration ratio In / Al of the first active layer 103a has a U-shaped distribution, and the element concentration ratio In / Al of the second active layer 103b has an M-shaped distribution, which can reduce the hole injection barrier, improve the efficiency of hole injection into the active layer, and improve the carrier localization effect, enhance the electron-hole recombination efficiency of the active layer, and at the same time, suppress the InN phase separation, segregation and composition fluctuation of the high In component green light laser, thereby further improving the crystal quality and interface quality of the active layer, reducing defects and non-radiative recombination centers, and improving the slope efficiency of the green light laser.

[0079] Figures 2 and 3 show the SIMS secondary ion mass spectra of the structure of the semiconductor green laser shown in the embodiments of this specification. According to the SIMS (Secondary Ion Mass Spectrometry, SIMS) secondary ion mass spectrometer test, the element concentration distribution between different layers can be seen. As shown in Figure 2, the horizontal axis represents the depth of the semiconductor laser, and from left to right are the upper confinement layer 105, the upper waveguide layer 104, the active layer 103, the lower waveguide layer 102, and the lower confinement layer 101. The left vertical axis represents the concentration of the element, and the right vertical axis represents the density of the element. Figure 3 further divides the active layer 103 into a first active layer 103a and a second active layer 103b.

[0080] In some embodiments, the element concentration ratio In / Al of the first active layer 103a is 10-100, the element concentration ratio In / Al of the second active layer 103b is 1E4-5E5, and the element concentration ratio In / Al of the second active layer 103b to the first active layer 103a is 1E3-5E4.

[0081] It can be clearly seen from FIG. 3 that the In element in the first active layer 103 a is distributed in an inverted V shape, and the In element in the second active layer b is distributed in an M shape.

[0082] Figure 7 shows a SIMS secondary ion mass spectrum of a semiconductor laser with angle variations indicated. The horizontal axis in Figure 7 represents the depth of the semiconductor laser. From left to right, the upper waveguide layer 104, the second active layer 103b, the first active layer 103a, and the lower waveguide layer 102 are represented. The left vertical axis represents the concentration of the element, and the right vertical axis represents the density of the element. As shown in Figure 7, the angle of decrease in the In element intensity from the second active layer 103b to the first active layer 103a is represented by α, and the angle of decrease in the In element intensity from the lower waveguide layer 102 to the first active layer 103a is represented by β. In some embodiments, 45° ≤ α ≤ 90°, and 45° ≤ β ≤ 90°. For example, α can be 45°, 60°, 90°, etc., and β can also be 45°, 60°, or 90°.

[0083] In some embodiments, the element concentration ratio In / Al decreases at an angle γ from the second active layer 103b toward the first active layer 103a: 35°≤γ≤90°, and the element concentration ratio In / Al decreases at an angle θ from the lower waveguide layer 102 toward the first active layer 103a: 35°≤θ≤90°, where: 35°≤γ≤θ≤α≤β≤90°. For example, γ is 35°, θ is 45°, α is 55°, and β is 65°.

[0084] In the embodiments of this specification, limiting the value of the element concentration ratio and the decrease angle within a range can alleviate the quantum confined Stark effect, reduce the piezoelectric polarization effect, reduce the band tilt of the active layer, reduce the valence band step, and improve the efficiency and transport capacity of hole injection into the active layer, thereby improving the carrier uniformity and laser lasing gain uniformity of the laser, and improving the lasing gain and slope efficiency of the laser.

[0085] In some embodiments, the lower confinement layer 101 may include any one or any combination of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN, and GaN. In some embodiments, the lower confinement layer 101 may include a first lower confinement layer, a second lower confinement layer, a third lower confinement layer, a fourth lower confinement layer, and a fifth lower confinement layer.

[0086] FIG8 shows a SIMS secondary ion mass spectrum of a lower confinement layer according to some embodiments of the present disclosure. The horizontal axis in FIG8 represents the depth of the semiconductor laser. From left to right, the upper confinement layer 105, upper waveguide layer 104, active layer 103, lower waveguide layer 102, fifth lower confinement layer 101e, fourth lower confinement layer 101d, third lower confinement layer 101c, second lower confinement layer 101b, and first lower confinement layer 101a are shown. The left vertical axis represents the concentration of the element, and the right vertical axis represents the density of the element. FIG8 shows that the distribution of Al, Si, H, O, and C varies significantly between the first lower confinement layer 101a, the second lower confinement layer 101b, the third lower confinement layer 101c, the fourth lower confinement layer 101d, and the fifth lower confinement layer 101e, but the variation trends between the different elements are generally consistent.

[0087] Figure 9 shows a TEM image of the lower confinement layers according to some embodiments of this specification, with a resolution of 200 nm. As can be seen in Figure 9 , there are significant variations in brightness and darkness between the first lower confinement layer 101a, the second lower confinement layer 101b, the third lower confinement layer 101c, and the fourth lower confinement layer 101d, due to the different material compositions of the different layers.

[0088] In some embodiments, the thermal expansion coefficient of the first lower confinement layer is a1, the thermal expansion coefficient of the second lower confinement layer is a2, the thermal expansion coefficient of the third lower confinement layer is a3, the thermal expansion coefficient of the fourth lower confinement layer is a4, the thermal expansion coefficient of the fifth lower confinement layer is a5, the thermal expansion coefficient of the lower waveguide layer 102 is b, the thermal expansion coefficient of the active layer 103 is c, the thermal expansion coefficient of the upper waveguide layer 104 is d, and the thermal expansion coefficient of the upper confinement layer 105 is f; the thermal expansion coefficient gradient of the semiconductor green laser has the following relationship: 2.5≤c≤d≤a3≤b≤a5≤a1≤f≤a2≤a4≤6.5(10 -6 / K). The thermal expansion coefficient can indicate the degree of change in the length, area, and volume of an object when heated.

[0089] In some embodiments, the dielectric constant of the first lower confinement layer is g1, the dielectric constant of the second lower confinement layer is g2, the dielectric constant of the third lower confinement layer is g3, the dielectric constant of the fourth lower confinement layer is g4, and the dielectric constant of the fifth lower confinement layer is g5. The dielectric constant of the lower waveguide layer 102 is h, the dielectric constant of the active layer 103 is i, the dielectric constant of the upper waveguide layer 104 is j, and the dielectric constant of the upper confinement layer 105 is k. The dielectric constant gradient of the semiconductor green laser has the following relationship: 8≤g4≤g2≤k≤g1≤g5≤h≤g3≤j≤i≤12. The dielectric constant is a coefficient that represents the insulation capability characteristic.

[0090] In some embodiments, the elastic coefficient C of the first lower restricting layer is 33 is s1, the elastic coefficient C of the second lower limiting layer 33 is s2, the elastic coefficient C of the third lower limiting layer 33 is s3, the elastic coefficient C of the fourth lower limiting layer is 33 is s4, the elastic coefficient C of the fifth lower limiting layer 33 is s5, the elastic coefficient C of the lower waveguide layer 102 33 is t, the elastic coefficient C of the active layer 103 33 is u, the elastic coefficient C of the upper waveguide layer 104 33 is v, the elastic coefficient C of the upper limiting layer 105 33 The elastic coefficient C of the semiconductor green laser is w; 33 The gradient has the following relationship: 200≤u≤v≤s3≤t≤s4≤s2≤w≤s1≤s5≤450GPa. The elastic modulus is the ratio of the percentage of deformation of the length of the material to the percentage of change in the applied force.

[0091] In the embodiments of this specification, the lower confinement layer 101 has gradients in thermal expansion coefficient, dielectric constant, and elastic coefficient C33. These gradients improve the uniformity of laser temperature distribution, reduce the uniformity of thermal expansion coefficient and thermal stress distribution, suppress temperature quenching, laser breakage, thermal lensing, and stress birefringence, improve laser beam depolarization and distortion, enhance the laser beam quality factor, and improve the focus spot resolution. The dielectric constant and elastic coefficient gradients also improve thermal mismatch, reduce threshold current, increase output optical power and slope efficiency, and mitigate optical field dissipation, suppressing optical field mode leakage into the substrate and enhancing far-field FFP image quality.

[0092] In some embodiments, the thermal expansion coefficient of the third lower confinement layer has a curve distribution of a seventh function, the seventh function is y=x / sinx, the elastic coefficient of the third lower confinement layer has a curve distribution of an eighth function, the eighth function is y=x / sinx, and the dielectric constant of the third lower confinement layer has a curve distribution of a ninth function y=Vx 2 +Ux+W(V<0), where x is a variable and V, U, and W are constants.

[0093] In summary, the lasers shown in the embodiments of this specification have better effects in terms of beam quality factor, slope efficiency, threshold current density, optical power and focused spot resolution compared to traditional lasers. The beam quality factor is a parameter for evaluating the quality of the beam. The closer the beam quality factor is to 1, the better the beam quality and the stronger the focusing ability. The slope efficiency is a physical quantity that measures the output characteristics of the laser. The higher the slope efficiency, the higher the efficiency of the laser and the greater the output power. The threshold current density is a physical quantity that characterizes the threshold lasing or oscillation achieved by an electrically injected semiconductor laser. Reducing the threshold current density can improve the laser conversion efficiency, reduce heat loss and enhance the output power. Optical power is the work done by light per unit time, which can represent the brightness or intensity of light. The focused spot resolution indicates the size of the spot size and depends on the laser wavelength. Shorter wavelength lasers can provide smaller spots and higher spatial resolution.

[0094] Specifically, compared with traditional lasers, the beam quality factor of the laser shown in the embodiment of this specification is reduced from 6.7 to 3.97, a decrease of about 69%; the slope efficiency is increased from 0.55W / A to 0.897W / A, an increase of about 62%; the threshold current density is reduced from 3.6KA / cm2 to 0.95KA / cm2, a decrease of about 74%; the optical power is increased from 1.05W to 1.49W, an increase of about 42%; and the focused spot resolution is reduced from greater than 250nm to less than 20nm, as shown in Table 1 below.

[0095] Table 1 Comparison of laser changes

[0096] While the basic concepts have been described above, it will be apparent to those skilled in the art that the detailed disclosure is merely illustrative and does not limit this specification. Although not explicitly stated herein, various modifications, improvements, and revisions to this specification may be made by those skilled in the art. Such modifications, improvements, and revisions are suggested in this specification and remain within the spirit and scope of the exemplary embodiments of this specification.

[0097] This specification also uses specific terms to describe the embodiments of this specification. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "one embodiment," "an embodiment," or "an alternative embodiment" two or more times in different locations in this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of this specification may be appropriately combined.

[0098] In addition, unless expressly stated in the claims, the order of the processing elements and sequences, the use of alphanumeric characters, or the use of other names described in this specification are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some of the invention embodiments currently considered useful through various examples, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the spirit and scope of the embodiments of this specification. For example, although the system components described above can be implemented by hardware devices, they can also be implemented only by software solutions, such as installing the described system on an existing server or mobile device.

[0099] Similarly, it should be noted that, in order to simplify the presentation of this specification and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of this specification sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not imply that the subject matter of this specification requires more features than those recited in the claims. In fact, an embodiment may have fewer features than all of the features of a single disclosed embodiment.

[0100] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the description and claims are approximate values, which may change according to the required characteristics of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of this specification are approximate values, in specific embodiments, the settings of such numerical values ​​are as accurate as possible within the feasible range.

[0101] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, and documents, cited in this specification is hereby incorporated by reference in its entirety. This includes application history documents that are inconsistent with or conflict with the content of this specification, as well as documents (currently or subsequently attached to this specification) that limit the broadest scope of the claims of this specification. It should be noted that if the descriptions, definitions, and / or terminology used in the accompanying materials are inconsistent or conflicting with the content of this specification, the descriptions, definitions, and / or terminology used in this specification will control.

[0102] Finally, it should be understood that the embodiments described in this specification are intended only to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, by way of example and not limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly described and illustrated in this specification.

Claims

1. A semiconductor green laser, characterized in that: The invention comprises, from bottom to top, a substrate (100), a lower confinement layer (101), a lower waveguide layer (102), an active layer (103), an upper waveguide layer (104), and an upper confinement layer (105), wherein: The active layer (103) is a quantum well composed of a well layer and a barrier layer, and the period of the quantum well is z, 1≤z≤3; The well layer includes any one or any combination of aluminum indium gallium nitride (AlInGaN), aluminum indium nitride (AlInN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), indium nitride (InN), indium gallium nitride (InGaN) and gallium nitride (GaN), and the thickness of the well layer is p, 5 angstroms ≤ p ≤ 100 angstroms; The barrier layer comprises any one or any combination of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN and GaN, and the thickness of the barrier layer is q, 10 angstroms ≤ q ≤ 200 angstroms; The electron effective mass of the well layer is smaller than the electron effective mass of the barrier layer, the spontaneous polarization coefficient of the well layer is smaller than the spontaneous polarization coefficient of the barrier layer, and the band gap width of the well layer is smaller than the band gap width of the barrier layer.

2. A semiconductor green laser according to claim 1, characterized in that: The active layer (103) comprises a first active layer (103a) and a second active layer (103b); The electron effective mass of the first active layer (103a) has an inverted U-shaped distribution; The electron effective mass of the second active layer (103b) has a W-shaped distribution; The spontaneous polarization coefficient of the first active layer (103a) has an inverted U-shaped distribution; The spontaneous polarization coefficient of the second active layer (103b) has a W-shaped distribution; The bandgap width of the first active layer (103a) has an inverted U-shaped distribution; The bandgap width of the second active layer (103b) has a W-shaped distribution.

3. A semiconductor green laser according to claim 2, characterized in that: The electron effective mass of the first active layer (103a) has a curve distribution of a first function, wherein the first function is y=Ax 2 +Bx+C(A<0); The spontaneous polarization coefficient of the first active layer (103a) has a curve distribution of a second function, and the second function is y=Dx 2 +Ex+F(D<0); The forbidden band width of the first active layer (103a) has a curve distribution of a third function, and the third function is y=Jx 2 +Kx+K(J<0); Among them, -500<A≤J≤D<0, and A, B, C, D, E, F, J, and K are constants.

4. A semiconductor green laser according to claim 2, characterized in that: The electron effective mass of the second active layer (103b) has a curve distribution of a fourth function, and the fourth function is y=Lcos(Mx+N); The spontaneous polarization coefficient of the second active layer (103b) has a curve distribution of a fifth function, and the fifth function is y=Pcos(Qx+O); The forbidden band width of the second active layer (103b) has a curve distribution of a sixth function, and the sixth function is y=Rcos(Sx+T); Among them, P≤R≤L, L, M, N, P, Q, O, R, S, and T are constants.

5. A semiconductor green laser according to claim 2, characterized in that: The electron effective mass of the first active layer (103a) is a, the electron effective mass of the well layer of the second active layer (103b) is b, and the electron effective mass of the barrier layer of the second active layer (103b) is c, wherein 0.05m e ≤b≤c≤a≤0.2m e ; The spontaneous polarization coefficient of the first active layer (103a) is d, the spontaneous polarization coefficient of the well layer of the second active layer (103b) is e, and the spontaneous polarization coefficient of the barrier layer of the second active layer (103b) is f, wherein -0.05C / m 2 ≤e≤f≤d≤-0.02C / m 2 ; The bandgap width of the first active layer (103a) is g, the bandgap width of the well layer of the second active layer (103b) is h, and the bandgap width of the barrier layer of the second active layer (103b) is i, wherein 0.5eV≤h≤i≤g≤3.5eV.

6. A semiconductor green laser according to claim 2, characterized in that: The element concentration ratio In / Al of the first active layer (103a) has a U-shaped distribution; The element concentration ratio In / Al of the second active layer (103b) has an M-type distribution; The element concentration ratio Si / H of Si and H in the first active layer (103a) is distributed in an inverted U shape, and the element concentration ratio Si / H of Si and H in the second active layer (103b) is distributed in a linear manner.

7. A semiconductor green laser according to claim 6, characterized in that: The element concentration ratio In / Al of the first active layer (103a) is 10-100, the element concentration ratio In / Al of the second active layer (103b) is 1E4-5E5, and the element concentration ratio In / Al of the second active layer (103b) to the first active layer (103a) is 1E3-5E4.

8. A semiconductor green laser according to claim 6, characterized in that: The In element intensity decreases at an angle α from the second active layer (103b) toward the first active layer (103a), and 45°≤α≤90°; The In element intensity decrease angle from the lower waveguide layer (102) toward the first active layer (103a) is β, 45°≤β≤90°; The element concentration ratio In / Al in the direction from the second active layer (103b) to the first active layer (103a) decreases at an angle γ, 35°≤γ≤90°; The element concentration ratio In / Al in the direction from the lower waveguide layer (102) to the first active layer (103a) decreases at an angle θ, 35°≤θ≤90°, Among them, 35°≤γ≤θ≤α≤β≤90°.

9. A semiconductor green laser according to claim 1, characterized in that: The lower confinement layer (101) comprises any one or any combination of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN and GaN; The lower confinement layer (101) includes a first lower confinement layer, a second lower confinement layer, a third lower confinement layer, a fourth lower confinement layer and a fifth lower confinement layer.

10. A semiconductor green laser according to claim 9, characterized in that: The thermal expansion coefficient of the first lower confinement layer is a1, the thermal expansion coefficient of the second lower confinement layer is a2, the thermal expansion coefficient of the third lower confinement layer is a3, the thermal expansion coefficient of the fourth lower confinement layer is a4, the thermal expansion coefficient of the fifth lower confinement layer is a5, the thermal expansion coefficient of the lower waveguide layer (102) is b, the thermal expansion coefficient of the active layer (103) is c, the thermal expansion coefficient of the upper waveguide layer (104) is d, and the thermal expansion coefficient of the upper confinement layer (105) is f; the thermal expansion coefficient gradient of the semiconductor green laser has the following relationship: 2.5(10 -6 / K)≤c≤d≤a3≤b≤a5≤a1≤f≤a2≤a4≤6.5(10 -6 / K).

11. The semiconductor green laser according to claim 9, characterized in that: The dielectric constant of the first lower limiting layer is g1, the dielectric constant of the second lower limiting layer is g2, the dielectric constant of the third lower limiting layer is g3, the dielectric constant of the fourth lower limiting layer is g4, the dielectric constant of the fifth lower limiting layer is g5, the dielectric constant of the lower waveguide layer (102) is h, the dielectric constant of the active layer (103) is i, the dielectric constant of the upper waveguide layer (104) is j, and the dielectric constant of the upper limiting layer (105) is k; the dielectric constant gradient of the semiconductor green laser has the following relationship: 8≤g4≤g2≤k≤g1≤g5≤h≤g3≤j≤i≤12.

12. The semiconductor green laser according to claim 9, characterized in that: The elastic coefficient C of the first lower restricting layer 33 is s1, the elastic coefficient C of the second lower limiting layer is 33 is s2, the elastic coefficient C of the third lower limiting layer 33 is s3, the elastic coefficient C of the fourth lower limiting layer 33 is s4, the elastic coefficient C of the fifth lower limiting layer 33 is s5, the elastic coefficient C of the lower waveguide layer (102) 33 is t, the elastic coefficient C of the active layer (103) 33 is u, the elastic coefficient C of the upper waveguide layer (104) 33 is v, the elastic coefficient C of the upper limiting layer (105) 33 is w; the elastic coefficient C of the semiconductor green laser 33 The gradient has the following relationship: 200 GPa≤u≤v≤s3≤t≤s4≤s2≤w≤s1≤s5≤450 GPa.

13. A semiconductor green laser according to claim 9, characterized in that: The thermal expansion coefficient of the third lower limiting layer has a curve distribution of a seventh function, the seventh function is y=x / sinx, the elastic coefficient of the third lower limiting layer has a curve distribution of an eighth function, the eighth function is y=x / sinx, and the dielectric constant of the third lower limiting layer has a curve distribution of a ninth function, the ninth function is y=Vx 2 +Ux+W(V<0), where V, U, and W are constants.

14. The semiconductor green laser according to claim 1, characterized in that: The lower waveguide layer (102) comprises any one or any combination of AlInGaN, AlInN, AlGaN, InGaN, InN and GaN, and the thickness of the lower waveguide layer (102) is 10 angstroms to 9000 angstroms; The upper waveguide layer (104) comprises any one or any combination of AlInGaN, AlInN, AlGaN, InGaN, InN and GaN, and the thickness of the upper waveguide layer (104) is 10 angstroms to 9000 angstroms; The upper confinement layer (105) comprises any one or any combination of AlInGaN, AlInN, AlN, AlGaN, InGaN and GaN, and the thickness of the upper confinement layer (105) is 10 angstroms to 8000 angstroms; The lower confinement layer (101) comprises any one or any combination of AlInGaN, AlInN, AlN, AlGaN and GaN, and the thickness of the lower confinement layer (101) is 10 angstroms to 90,000 angstroms; The substrate (100) includes sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, Mo, TiW, Cu, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, diamond, sapphire / SiN x , Sapphire / SiN x / SiO2 composite substrate, sapphire / SiO2 / SiN x Any one of a composite substrate, a magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

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