A semiconductor laser

Abstract

The present invention discloses a semiconductor laser comprising: a substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, and an upper confinement layer, arranged in order from bottom to top; the active layer comprising a well layer and a barrier layer; the electron effective mass of the well layer of the active layer being smaller than the electron effective mass of the barrier layer, the spontaneous polarization coefficient of the well layer of the active layer being smaller than the spontaneous polarization coefficient of the barrier layer, and the bandgap width of the well layer of the active layer being smaller than the bandgap width of the barrier layer. The present invention can suppress InN phase separation, segregation, and composition fluctuation in high-In content semiconductor lasers, effectively improve the crystal quality and interface quality of the active layer, effectively enhance the electron-hole recombination efficiency of the active layer, and effectively reduce defects and non-radiative recombination centers, thereby effectively improving the slope efficiency of green lasers.

Description

Technical Field

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

[0002] Lasers are widely used in laser displays, laser televisions, laser projectors, communications, medical treatment, guidance, distance measurement, 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.

[0003] The efficiency of hole injection into the active layer of existing semiconductor lasers is low, resulting in low slope efficiency of the semiconductor lasers. Summary of the Invention

[0004] The present invention provides a semiconductor laser to solve the technical problem that the efficiency of hole injection into an active layer of an existing semiconductor laser is low, resulting in low slope efficiency of the semiconductor laser.

[0005] One embodiment of the present invention provides a semiconductor laser, comprising:

[0006] A substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper confinement layer are sequentially arranged from bottom to top;

[0007] The active layer includes a well layer and a barrier layer;

[0008] The electron effective mass of the well layer of the active layer is smaller than the electron effective mass of the barrier layer, the spontaneous polarization coefficient of the well layer of the active layer is smaller than the spontaneous polarization coefficient of the barrier layer, and the band gap width of the well layer of the active layer is smaller than the band gap width of the barrier layer.

[0009] Furthermore, the active layer includes a first active layer and a second active layer;

[0010] The electron effective mass, spontaneous polarization coefficient and band gap width of the first active layer all have an inverted U-shaped distribution;

[0011] The electron effective mass, spontaneous polarization coefficient and band gap width of the second active layer all have an inverted W-shaped distribution.

[0012] Furthermore, 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 0.05≤b≤c≤a≤0.2.

[0013] Furthermore, 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 -0.05≤e≤f≤d≤-0.02.

[0014] Furthermore, 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 0.5≤h≤i≤g≤3.5.

[0015] Furthermore, the well layer of the active layer and the barrier layer of the active layer form a quantum well, and the period of the quantum well is x: 1≤x≤3;

[0016] The well layer of the active layer includes at least one of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN and GaN, and the thickness of the well layer of the active layer is p: 10≤p≤100 angstroms; the barrier layer of the active layer includes at least one of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN and GaN, and the thickness of the barrier layer of the active layer is q: 10≤q≤200 angstroms.

[0017] Furthermore, the active layer includes a first active layer and a second active 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; the Si / H element ratio of the first active layer has an inverted U-shaped distribution, and the Si / H element ratio of the second active layer has a linear distribution.

[0018] Furthermore, the lower waveguide layer includes at least one of AlInGaN, AlInN, AlGaN, InGaN, InN and GaN, and has a thickness of 10 angstroms to 9000 angstroms; the upper waveguide layer includes at least one of AlInGaN, AlInN, AlGaN, InGaN, InN and GaN, and has a thickness of 10 angstroms to 9000 angstroms; the upper confinement layer includes at least one of AlInGaN, AlInN, AlN, AlGaN, InGaN and GaN, and has a thickness of 10 angstroms. ~8000 angstroms; the lower confinement layer includes at least one of AlInGaN, AlInN, AlN, AlGaN and GaN, with a thickness of 10 angstroms to 90,000 angstroms; the substrate includes one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, sapphire / SiNx, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0019] In the embodiment of the present invention, the electron effective mass of the well layer of the active layer is smaller than the electron effective mass of the barrier layer, which can reduce the hole injection barrier efficiency and improve the hole injection efficiency into the active layer. It can also suppress the InN phase separation, segregation and composition fluctuation of the high In component semiconductor laser, thereby reducing defects and non-radiative recombination centers, and thus effectively improving the slope efficiency of the green laser; the spontaneous polarization coefficient of the well layer of the active layer is smaller than the spontaneous polarization coefficient of the barrier layer, which can effectively reduce the polarization effect of the semiconductor laser, thereby suppressing the InN phase separation, segregation and composition fluctuation of the high In component semiconductor, improving the carrier localization effect, and thus effectively enhancing the electron-hole recombination efficiency of the active layer and improving the slope efficiency of the semiconductor laser; the band gap width of the well layer of the active layer is smaller than the band gap width of the barrier layer, which can effectively improve the crystal quality and interface quality of the active layer, thereby effectively reducing defects and non-radiative recombination centers, and thus improving the slope efficiency of the green laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 1 is a schematic structural diagram of a semiconductor laser provided by an embodiment of the present invention;

[0021] Figure 2 This is a SIMS secondary ion mass spectrum of a semiconductor laser provided by an embodiment of the present invention;

[0022] Figure 3 is another SIMS secondary ion mass spectrum of the semiconductor laser provided by an embodiment of the present invention;

[0023] Figure 4 This is an electron microscope image of a TEM lens of an active layer of a semiconductor laser provided by an embodiment of the present invention;

[0024] Figure 5 This is a TEM lens electron microscope image of the upper waveguide layer of the semiconductor laser provided by an embodiment of the present invention;

[0025] Figure 6 This is an electron microscope image of a TEM lens of the upper confinement layer of a semiconductor laser provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0028] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0029] See also Figure 1 One embodiment of the invention provides a semiconductor laser, comprising:

[0030] The substrate 100, the lower confinement layer 101, the lower waveguide layer 102, the active layer 103, the upper waveguide layer 104 and the upper confinement layer 105 are arranged in sequence from bottom to top;

[0031] The active layer 103 includes a well layer and a barrier layer;

[0032] 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 of the active layer 103 is smaller than the spontaneous polarization coefficient of the barrier layer, and the band gap width of the well layer of the active layer 103 is smaller than the band gap width of the barrier layer.

[0033] In an embodiment of the present invention, the active layer 103 comprises a periodic structure consisting of a well layer and a barrier layer. In this embodiment of the present invention, the electron effective mass of the well layer of the active layer 103 is smaller than the electron effective mass of the barrier layer, which can reduce the hole injection barrier efficiency and improve the efficiency of hole injection into the active layer 103. Furthermore, the active layer 103 can suppress InN phase separation, segregation, and composition fluctuations in high-In content semiconductor lasers, thereby reducing defects and non-radiative recombination centers, thereby effectively improving the slope efficiency of green lasers.

[0034] In the embodiment of the present invention, the spontaneous polarization coefficient of the well layer of the active layer 103 is smaller than the spontaneous polarization coefficient of the barrier layer, which can effectively reduce the polarization effect of the semiconductor laser, thereby suppressing the InN phase separation, segregation and composition fluctuation of the high In composition semiconductor, improving the carrier localization effect, and further effectively enhancing the electron-hole recombination efficiency of the active layer 103 and improving the slope efficiency of the semiconductor laser.

[0035] The bandgap width of the well layer of the active layer 103 in the embodiment of the present invention is smaller than the bandgap width of the barrier layer, which can effectively improve the crystal quality and interface quality of the active layer 103, thereby effectively reducing defects and non-radiative recombination centers, thereby improving the slope efficiency of the green laser.

[0036] In one embodiment, the active layer 103 includes a first active layer 1031 and a second active layer 1032 ;

[0037] The electron effective mass, spontaneous polarization coefficient and band gap width of the first active layer 1031 all have an inverted U-shaped distribution;

[0038] The electron effective mass, spontaneous polarization coefficient and band gap width of the second active layer 1032 all have an inverted W-shaped distribution.

[0039] In the embodiment of the present invention, the electron effective mass of the first active layer 1031 has an inverted U-shaped distribution, and the electron effective mass of the second active layer 1032 has a W-shaped distribution, thereby further reducing the hole injection barrier, improving the efficiency of hole injection into the active layer 103, and suppressing the InN phase separation, segregation and composition fluctuation of the high In composition green laser, reducing defects and non-radiative recombination centers, and improving the slope efficiency of the green laser;

[0040] The spontaneous polarization coefficient of the first active layer 1031 has an inverted U-shaped distribution; the spontaneous polarization coefficient of the second active layer 1032 has a W-shaped distribution, which can further reduce the polarization effect, suppress the InN phase separation, segregation and composition fluctuation of the high In component green laser, improve the carrier localization effect, enhance the electron-hole recombination efficiency of the active layer 103, and improve the slope efficiency of the green laser.

[0041] The bandgap width of the first active layer 1031 has an inverted U-shaped distribution, and the bandgap width of the second active layer 1032 has a W-shaped distribution, which can further improve the crystal quality and interface quality of the active layer 103, reduce defects and non-radiative recombination centers, and improve the slope efficiency of the green laser.

[0042] In one embodiment, the electron effective mass of the first active layer 1031 is a, the electron effective mass of the well layer of the second active layer 1032 is b, and the electron effective mass of the barrier layer of the second active layer 1032 is c, wherein 0.05≤b≤c≤a≤0.2.

[0043] In one embodiment, the spontaneous polarization coefficient of the first active layer 1031 is d, the spontaneous polarization coefficient of the well layer of the second active layer 1032 is e, and the spontaneous polarization coefficient of the barrier layer of the second active layer 1032 is f, wherein -0.05≤e≤f≤d≤-0.02.

[0044] In one embodiment, the bandgap width of the first active layer 1031 is g, the bandgap width of the well layer of the second active layer 1032 is h, and the bandgap width of the barrier layer of the second active layer 1032 is i, wherein 0.5≤h≤i≤g≤3.5.

[0045] In one embodiment, the well layer of the active layer 103 and the barrier layer of the active layer form a quantum well, and the period of the quantum well is x: 1≤x≤3;

[0046] The well layer of the active layer 103 includes at least one of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN and GaN, and the thickness of the well layer of the active layer 103 is p: 10≤p≤100 angstroms; the barrier layer of the active layer 103 includes at least one of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN and GaN, and the thickness of the barrier layer of the active layer 103 is q: 10≤q≤200 angstroms.

[0047] In an embodiment of the present invention, the quantum well is a periodic structure, and its period can be x:1≤x≤3. In an embodiment of the present invention, since the current density of the semiconductor laser is dozens or even hundreds of times that of the LED, too many quantum wells will cause heat accumulation, causing the device to burn out, and the semiconductor laser requires the quality and interface of the active layer 103 to be very good, so that the wavelength half-width of the laser emission is narrow, forming a single-mode emission. Too many quantum well logarithms will cause the In component to fluctuate, the half-width becomes larger, and the laser generates multi-mode. Therefore, in an embodiment of the present invention, the quantum well composed of the well layer of the active layer 103 and the barrier layer of the active layer 103 has a period of no more than 3 to avoid heat accumulation in the quantum well and multi-mode generation of the laser.

[0048] In one embodiment, the active layer 103 includes a first active layer 1031 and a second active layer 1032; the In / Al element ratio of the first active layer 1031 has a U-shaped distribution; the In / Al element ratio of the second active layer 1032 has an M-shaped distribution; the Si / H element ratio of the first active layer 1031 has an inverted U-shaped distribution, and the Si / H element ratio of the second active layer 1032 has a linear distribution.

[0049] In the embodiment of the present invention, the In / Al element ratio of the first active layer 1031 has a U-shaped distribution; the In / Al element ratio of the second active layer 1032 has an M-shaped distribution, thereby reducing the hole injection barrier, improving the efficiency of hole injection into the active layer, reducing the polarization effect, suppressing the InN phase separation, segregation and composition fluctuation of the high In composition green laser, improving the carrier localization effect, enhancing the electron-hole recombination efficiency of the active layer, and improving the slope efficiency of the green laser.

[0050] The Si / H element ratio of the first active layer 1031 is distributed in an inverted U shape, and the Si / H element ratio of the second active layer 1032 is distributed linearly, thereby improving the crystal quality and interface quality of the active layer 103, reducing defects and non-radiative recombination centers, and suppressing InN phase separation, segregation and composition fluctuation of a high In component green laser, reducing defects and non-radiative recombination centers, and improving the slope efficiency of the green laser.

[0051] In one embodiment, the lower waveguide layer 102 comprises at least one of AlInGaN, AlInN, AlGaN, InGaN, InN and GaN, and has a thickness of 10 angstroms to 9000 angstroms; the upper waveguide layer 104 comprises at least one of AlInGaN, AlInN, AlGaN, InGaN, InN and GaN, and has a thickness of 10 angstroms to 9000 angstroms; the upper confinement layer 105 comprises at least one of AlInGaN, AlInN, AlN, AlGaN, InGaN and GaN, and has a thickness of 10 angstroms to 8 000 angstroms; the lower confinement layer 101 includes at least one of AlInGaN, AlInN, AlN, AlGaN and GaN, and has a thickness of 10 angstroms to 90,000 angstroms; the substrate 100 includes one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, sapphire / SiO2 composite substrate 100, sapphire / AlN composite substrate 100, sapphire / SiNx, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate 100.

[0052] See also Figure 2-3 , which are respectively a SIMS secondary ion mass spectrum and another SIMS secondary ion mass spectrum of the semiconductor laser provided in an embodiment of the present invention.

[0053] See also Figure 4-6 , which are TEM lens electron microscope images of the active layer 103, the upper waveguide layer 104 and the upper confinement layer 105 of the semiconductor laser provided by an embodiment of the present invention, respectively.

[0054] Please refer to Table 1, which is a data comparison table of the semiconductor laser provided by the embodiment of the present invention and the traditional laser.

[0055]

[0056] As shown in Table 1, compared with traditional lasers, the slope efficiency of the semiconductor laser provided by the embodiment of the present invention is improved from 0.35 W / A to 0.91 W / A, an increase of 153%; the threshold current density is improved from 4.8 kA / cm2 to 1.18 kA / cm2, a decrease of about 75%; and the optical power is increased from 0.6 W to 1.13 W, an increase of about 88%.

[0057] The implementation of the present invention has the following beneficial effects:

[0058] In the embodiment of the present invention, the electron effective mass of the well layer of the active layer 103 is smaller than the electron effective mass of the barrier layer, which can reduce the hole injection barrier efficiency and improve the hole injection efficiency into the active layer. It can also suppress the InN phase separation, segregation and composition fluctuation of the high In content semiconductor laser, thereby reducing defects and non-radiative recombination centers, and thus effectively improving the slope efficiency of the green laser. The spontaneous polarization coefficient of the well layer of the active layer 103 is smaller than the spontaneous polarization coefficient of the barrier layer, which can effectively reduce the polarization effect of the semiconductor laser, thereby suppressing the InN phase separation, segregation and composition fluctuation of the high In content semiconductor, improving the carrier localization effect, and thus effectively enhancing the electron-hole recombination efficiency of the active layer and improving the slope efficiency of the semiconductor laser. The band gap width of the well layer of the active layer 103 is smaller than the band gap width of the barrier layer, which can effectively improve the crystal quality and interface quality of the active layer, thereby effectively reducing defects and non-radiative recombination centers, and thus improving the slope efficiency of the green laser.

[0059] The above is 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 principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A semiconductor laser, characterized in that include: A substrate, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer and an upper confinement layer are sequentially arranged from bottom to top; The active layer includes a well layer and a barrier layer; The electron effective mass of the well layer of the active layer is smaller than the electron effective mass of the barrier layer, the spontaneous polarization coefficient of the well layer of the active layer is smaller than the spontaneous polarization coefficient of the barrier layer, and the band gap width of the well layer of the active layer is smaller than the band gap width of the barrier layer; The active layer includes a first active layer and a second active layer; The electron effective mass, spontaneous polarization coefficient and band gap width of the first active layer all have an inverted U-shaped distribution; The electron effective mass, spontaneous polarization coefficient and band gap width of the second active layer all have an inverted W-shaped distribution.

2. The semiconductor laser according to claim 1, wherein 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 0.05≤b≤c≤a≤0.

2.

3. The semiconductor laser according to claim 1, wherein 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 -0.05≤e≤f≤d≤-0.

02.

4. The semiconductor laser according to claim 1, wherein 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 0.5≤h≤i≤g≤3.

5.

5. The semiconductor laser according to claim 1, wherein The well layer of the active layer and the barrier layer of the active layer form a quantum well, and the period of the quantum well is x: 1≤x≤3; The well layer of the active layer includes at least one of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN and GaN, and the thickness of the well layer of the active layer is p: 10≤p≤100 angstroms; the barrier layer of the active layer includes at least one of AlInGaN, AlInN, AlGaN, AlN, InN, InGaN and GaN, and the thickness of the barrier layer of the active layer is q: 10≤q≤200 angstroms.

6. The semiconductor laser according to claim 1, wherein The active layer includes a first active layer and a second active 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; the Si / H element ratio of the first active layer has an inverted U-shaped distribution, and the Si / H element ratio of the second active layer has a linear distribution.

7. The semiconductor laser according to claim 1, wherein The lower waveguide layer includes at least one of AlInGaN, AlInN, AlGaN, InGaN, InN and GaN, and has a thickness of 10 angstroms to 9000 angstroms; the upper waveguide layer includes at least one of AlInGaN, AlInN, AlGaN, InGaN, InN and GaN, and has a thickness of 10 angstroms to 9000 angstroms; the upper confinement layer includes at least one of AlInGaN, AlInN, AlN, AlGaN, InGaN and GaN, and has a thickness of 10 angstroms to 80 00 angstroms; the lower confinement layer includes at least one of AlInGaN, AlInN, AlN, AlGaN and GaN, and has a thickness of 10 angstroms to 90,000 angstroms; the substrate includes one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, sapphire / SiO2 composite substrate, sapphire / AlN composite substrate, sapphire / SiNx, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

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