A gallium nitride-based semiconductor laser chip element

Abstract

The application provides a gallium nitride-based semiconductor laser chip element, which comprises a substrate and an epitaxial layer, the epitaxial layer is arranged on the upper layer of the substrate, a first cavity surface of the epitaxial layer is coated with an anti-reflection layer, and a second cavity surface of the epitaxial layer is coated with a high-reflection layer; the anti-reflection layer comprises a first sub-anti-reflection layer, a multilayer second sub-anti-reflection layer and a multilayer third sub-anti-reflection layer which are sequentially arranged on the first cavity surface; the multilayer second sub-anti-reflection layer and the multilayer third sub-anti-reflection layer are alternately arranged to form a periodic structure; the anti-reflection layer comprises a plurality of peak electric field strengths and a plurality of valley electric field strengths; the maximum value of the plurality of peak electric field strengths is located in the middle region of the anti-reflection layer, and the electric field strength gradually decreases from the middle region to both sides. The application can improve the quantum efficiency of the laser and reduce the threshold current density.

Description

Technical Field

[0001] This application relates to the field of semiconductor optoelectronic devices, and more particularly to a gallium nitride-based semiconductor laser chip element. Background Technology

[0002] Lasers are widely used in laser displays, laser TVs, laser projectors, communications, medical applications, weaponry, guidance, ranging, spectral analysis, cutting, precision welding, and high-density optical storage. There are many types of lasers, and they can be classified in various ways, mainly including solid-state, gas, liquid, semiconductor, and dye lasers. Compared with other types of lasers, all-solid-state semiconductor lasers have advantages such as small size, high efficiency, light weight, good stability, long lifespan, simple and compact structure, and miniaturization.

[0003] Lasers and nitride semiconductor light-emitting diodes (LEDs) differ significantly:

[0004] 1) Lasers are generated by stimulated emission of charge carriers. They have a small half-width at half-maximum and very high brightness. The output power of a single laser can be in the W range. In contrast, nitride semiconductor light-emitting diodes are spontaneously emitted, and the output power of a single light-emitting diode is in the mW range.

[0005] 2) The operating current density of lasers reaches KA / cm2, which is more than two orders of magnitude higher than that of nitride light-emitting diodes. This results in stronger electron leakage, more severe Auger recombination, stronger polarization effect, and more severe electron-hole mismatch, leading to more severe efficiency degradation and the Droop effect.

[0006] 3) Light-emitting diodes emit spontaneous transition radiation, which is incoherent light that transitions from a high energy level to a low energy level without external influence. In contrast, lasers emit stimulated transition radiation, where the energy of the induced photon should be equal to the energy difference of the electron transition, producing coherent light that is identical to the induced photon.

[0007] 4) Different principles: Light emission diodes emit light by electrons and holes jumping to quantum wells or pn junctions under the action of external voltage, generating radiative recombination. Lasers, on the other hand, require certain lasing conditions to be met before they can emit light. This requires the carriers in the active region to be reversed, the stimulated emission light to oscillate back and forth in the resonant cavity, and the propagation in the gain medium to amplify the light. When the threshold condition is met, the gain is greater than the loss, and finally, laser light is output.

[0008] Nitride semiconductor lasers have the following problems: optical loss occurs when the light field is far from the active region and close to the electron blocking layer, which reduces the confinement of charge carriers by the quantum well and causes electron leakage; abnormal light field distribution can cause light field leakage, which increases the diffraction efficiency of the laser, increases the vertical divergence angle, reduces the beam quality, and reduces the light field confinement factor. Summary of the Invention

[0009] To address one of the aforementioned technical problems, this invention provides a gallium nitride-based semiconductor laser chip element.

[0010] This invention provides a gallium nitride-based semiconductor laser chip element, including a substrate and an epitaxial layer. The epitaxial layer is disposed on the upper layer of the substrate. The left and right sides of the epitaxial layer are a first cavity surface and a second cavity surface, respectively. A laser is emitted along the direction from the second cavity surface to the first cavity surface. An antireflection layer is deposited on the surface of the first cavity surface, and a high reflection layer is deposited on the surface of the second cavity surface. The antireflection layer includes a first sub-antireflection layer sequentially deposited on the surface of the first cavity surface, and a periodic structure formed by alternating second and third sub-antireflection layers. The electric field intensity of the simulated optical field distribution of the antireflection layer is a periodic oscillating distribution. The antireflection layer includes multiple peak electric field intensities and multiple valley electric field intensities. The maximum value of the multiple peak electric field intensities is located in the central region of the antireflection layer, and the electric field intensity gradually decreases from the central region to both sides.

[0011] Preferably, the antireflective layer has a reflectivity of 60% to 85% at a laser wavelength of 500 nm to 535 nm, and the high reflectivity layer has a reflectivity of 95% to 100% at a laser wavelength of 500 nm to 535 nm.

[0012] Preferably, the antireflective layer has 6 to 15 layers.

[0013] Preferably, the antireflective layer has 8 layers, and the antireflective layer includes 5 peak electric field intensities. The first cavity surface includes 2 peak electric field intensities. The first and second peak electric field intensities are located in the first cavity surface. The third peak electric field intensity is located in the first layer of the second sub-antireflective layer. The fourth peak electric field intensity is located in the first layer of the third sub-antireflective layer, and the fourth peak electric field intensity is the maximum value among the peak electric field intensities. The fifth peak electric field intensity is located in the interface region between the second layer of the second sub-antireflective layer and the second layer of the third sub-antireflective layer. The sixth peak electric field intensity is located in the interface region between the third layer of the second sub-antireflective layer and the third layer of the third sub-antireflective layer. The seventh peak electric field intensity is located in the interface region between the fourth layer of the second sub-antireflective layer and the air. The fourth peak electric field intensity ≥ the second peak electric field intensity ≥ the first peak electric field intensity ≥ the third valley electric field intensity ≥ the fifth valley electric field intensity ≥ the sixth peak electric field intensity ≥ the seventh peak electric field intensity.

[0014] Preferably, the ratio of the fourth peak electric field intensity to the second peak electric field intensity is a: 1≤a≤2.0, the ratio of the fourth peak electric field intensity to the first peak electric field intensity is b: 1.2≤b≤1.8, the ratio of the fourth peak electric field intensity to the third peak electric field intensity is c: 1.5≤c≤2.5, the ratio of the fourth peak electric field intensity to the fifth peak electric field intensity is d: 1.5≤d≤4, the ratio of the fourth peak electric field intensity to the sixth peak electric field intensity is e: 2.0≤e≤10, and the ratio of the fourth peak electric field intensity to the seventh peak electric field intensity is f: 5≤f≤100, and a≤b≤c≤d≤e≤f.

[0015] Preferably, the antireflective layer has 8 layers, and the antireflective layer includes 5 valley electric field intensities. The first cavity surface includes 1 valley electric field intensity. The first valley electric field intensity is located in the first cavity surface. The second valley electric field intensity is located in the first sub-antireflective layer. The third valley electric field intensity is located in the first second sub-antireflective layer. The fourth valley electric field intensity is located in the interface region between the first third sub-antireflective layer and the second second sub-antireflective layer. The fifth valley electric field intensity is located in the interface region between the second third sub-antireflective layer and the third second sub-antireflective layer. The sixth valley electric field intensity is greater than or equal to the fifth valley electric field intensity, the fourth valley electric field intensity, the third valley electric field intensity, the second valley electric field intensity, and the first valley electric field intensity.

[0016] Preferably, the antireflective layer has 8 layers;

[0017] The electric field intensity of the first cavity surface has a curve distribution of the function y1=asin(bx1+c)+d;

[0018] The electric field intensity of the first sub-antireflection layer has a curve distribution of the function y2=fcos(gx2+h)+i;

[0019] The electric field intensity of the first and second sub-antireflection layers has a curve distribution of the function y3=jsin(kx3+m)+n;

[0020] The electric field intensity of the first and third sub-antireflection layers has a function y4 = psin(qx4 + r) + s curve distribution;

[0021] The electric field intensity of the second sub-antireflection layer has a function y5=tsin(ux5+v)+w curve distribution;

[0022] The electric field intensity of the second and third sub-antireflection layers has a function y6=Vsin(Wx6+O)+Z curve distribution;

[0023] The electric field intensity of the third layer, second sub-antireflection layer, has a function y7=Jsin(Kx7+L)+M curve distribution;

[0024] The electric field intensity of the third sub-antireflection layer has a function y8=Ncos(Px8+L)+Q curve distribution;

[0025] The electric field intensity of the second sub-antireflection layer of the fourth layer has a curve distribution of the function y9=Rsin(Sx9+T)+U;

[0026] Where x1 is the thickness of the epitaxial layer, x2 is the thickness of the first sub-antireflective layer, x3 is the thickness of the first second sub-antireflective layer, x4 is the thickness of the first third sub-antireflective layer, x5 is the thickness of the second second sub-antireflective layer, x6 is the thickness of the second third sub-antireflective layer, x7 is the thickness of the third second sub-antireflective layer, x8 is the thickness of the third third sub-antireflective layer, x9 is the thickness of the fourth second sub-antireflective layer, U≤Q≤M≤Z≤w≤n≤d≤i≤s, R≤N≤J≤V≤t≤j≤a≤f≤p.

[0027] Preferably, the first sub-antireflective layer is Al2O3, the second sub-antireflective layer is Ta2O5 or SiO2, and the third sub-antireflective layer is SiN. x Or SiO2.

[0028] Preferably, when the number of antireflection layers is 8, the second sub-antireflection layer is Ta2O5, and the third sub-antireflection layer is SiO2, the quarter-wavelengths of the first sub-antireflection layer, the first second sub-antireflection layer, the first third sub-antireflection layer, the second second sub-antireflection layer, the second third sub-antireflection layer, the third second sub-antireflection layer, the third third sub-antireflection layer, and the fourth second sub-antireflection layer are 0.8 to 1.2, 1.9 to 2.3, 1.5 to 1.9, 0.8 to 1.2, 0.8 to 1.2, 0.8 to 1.2, 0.8 to 1.2, and 0.8 to 1.2, respectively. The quarter-wavelength of the first sub-antireflection layer ≤ the quarter-wavelength of the fourth second sub-antireflection layer ≤ the quarter-wavelength of the third second sub-antireflection layer ≤ the quarter-wavelength of the second second sub-antireflection layer ≤ the quarter-wavelength of the third third sub-antireflection layer ≤ the quarter-wavelength of the first third sub-antireflection layer ≤ the quarter-wavelength of the first second sub-antireflection layer.

[0029] Preferably, the epitaxial layer comprises, from bottom to top, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, and an upper confinement layer, wherein the epitaxial layer is any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond.

[0030] Preferably, the substrate comprises sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, graphene, sapphire / SiN x Sapphire / SiO2 / SiN x Composite substrate, sapphire / SiN x Any one of the following: SiO2 composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0031] The beneficial effects of this invention are as follows: In this invention, an antireflection layer and a high-reflection layer are deposited on both sides of the epitaxial layer of a gallium nitride-based semiconductor laser chip element. The antireflection layer includes a first sub-antireflection layer, multiple second sub-antireflection layers, and multiple third sub-antireflection layers sequentially deposited on the surface of the first cavity surface. The multiple second and third sub-antireflection layers are alternately arranged to form a periodic structure. The electric field intensity of the simulated optical field distribution in the antireflection layer is a periodic oscillating distribution. The antireflection layer includes multiple peak electric field intensities and multiple valley electric field intensities. The maximum value of the multiple peak electric field intensities is located in the central region of the antireflection layer, and the electric field intensity gradually decreases from the central region to both sides. This invention enables the optical field distribution to shift from the p-type side waveguide to the n-type side waveguide, so that the optical field of the active layer falls on the n-type side closer to the n-type side. This enhances the confinement of carriers by the quantum well, suppresses electron leakage, reduces free carrier loss, and reduces the overlap ratio between the optical field and the highly doped p-type electron blocking layer and the upper confinement layer. This reduces optical absorption loss, suppresses Joule heating, lowers the temperature of the active layer, improves the quantum efficiency of the laser, and reduces the threshold current density. Attached Figure Description

[0032] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0033] Figure 1 This is a schematic diagram of the structure of the gallium nitride-based semiconductor laser chip element according to an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the antireflection layer according to an embodiment of the present invention, which has 8 layers;

[0035] Figure 3 This is a schematic diagram of the antireflection layer according to an embodiment of the present invention, which has 10 layers;

[0036] Figure 4 This is a schematic diagram of the antireflection layer according to an embodiment of the present invention, which has 11 layers;

[0037] Figure 5 The electric field intensity distribution diagram is a simulated optical field distribution diagram of the gallium nitride-based semiconductor laser chip element according to an embodiment of the present invention, with 8 antireflection layers;

[0038] Figure 6 This is a schematic diagram of the epitaxial layer described in an embodiment of the present invention.

[0039] Figure label:

[0040] 100. Substrate; 101. Epitaxial layer; 102. Antireflection layer; 103. High reflectivity layer;

[0041] 1011, First cavity surface; 1012, Second cavity surface;

[0042] 1021, First sub-anti-reflection layer; 1022, Second sub-anti-reflection layer; 1023, Third sub-anti-reflection layer. Detailed Implementation

[0043] To make the technical solutions and advantages of the embodiments of this application clearer, the exemplary embodiments of this application will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0044] like Figure 1As shown, this embodiment proposes a gallium nitride-based semiconductor laser chip element, including a substrate 100 and an epitaxial layer 101. The epitaxial layer 101 is disposed on the upper layer of the substrate 100. A first cavity surface 1011 and a second cavity surface 1012 are located on the left and right sides of the epitaxial layer 101, respectively. The first cavity surface 1011 is located at the far end of the laser emission direction, and the second cavity surface 1012 is located at the near end of the laser emission direction, i.e., the laser is emitted along the direction from the second cavity surface 1012 to the first cavity surface 1011. An antireflection layer 102 is deposited on the surface of the first cavity surface 1011. A high reflectivity layer 103 is deposited on the surface of the second cavity surface 1012.

[0045] Specifically, in this embodiment, the antireflection layer 102 on the surface of the first cavity surface 1011 includes a periodic structure formed by a first sub-antireflection layer 1021 sequentially deposited on the surface of the first cavity surface 1011, a second sub-antireflection layer 1022, and a third sub-antireflection layer 1023 alternately disposed sequentially, such as... Figure 2 The diagram shows a schematic of an antireflection layer 102 structure formed by alternating four layers of second sub-antireflection layers 1022 and three layers of third sub-antireflection layers 1023 (this diagram is for illustrative purposes only and does not represent the actual dimensions). In this antireflection layer 102, the electric field intensity exhibits a periodic oscillating distribution, and includes multiple peak electric field intensities and multiple valley electric field intensities. The maximum value of the multiple peak electric field intensities is located in the central region of the antireflection layer 102, and the electric field intensity gradually decreases from this central region towards both sides (the first cavity surface 1011 side and the air side).

[0046] In this embodiment, an antireflection layer 102 and a high reflection layer 103 are deposited on both sides of the epitaxial layer 101 of the gallium nitride-based semiconductor laser chip element. The antireflection layer 102 includes a first sub-antireflection layer 1021, multiple layers of second sub-antireflection layers 1022 and multiple layers of third sub-antireflection layers 1023 sequentially deposited on the surface of the first cavity surface 1011. The multiple layers of second sub-antireflection layers 1022 and multiple layers of third sub-antireflection layers 1023 are alternately arranged to form a periodic structure. The electric field intensity of the antireflection layer 102 is periodically oscillating and includes multiple peak electric field intensities and multiple valley electric field intensities. The maximum value of the multiple peak electric field intensities is located in the central region of the antireflection layer 102, and the electric field intensity gradually decreases from the central region to both sides (the first cavity surface 1011 side and the air side). This invention enables the optical field distribution to shift from the p-type side waveguide to the n-type side waveguide, so that the optical field of the active layer falls on the n-type side closer to the n-type side. This enhances the confinement of carriers by the quantum well, suppresses electron leakage, reduces free carrier loss, and reduces the overlap ratio between the optical field and the highly doped p-type electron blocking layer and the upper confinement layer. This reduces optical absorption loss, suppresses Joule heating, lowers the temperature of the active layer, improves the quantum efficiency of the laser, and reduces the threshold current density.

[0047] In some optional embodiments, the number of antireflective layers 102 can be designed to be 6 to 15. The first sub-antireflective layer 1021 is fixed at 1 layer, while the number of the second sub-antireflective layers 1022 and the third sub-antireflective layers 1023 can be determined based on the total number of antireflective layers 102. If the number of antireflective layers 102 is 8, then the first sub-antireflective layer 1021 is 1 layer, the second sub-antireflective layer 1022 is 4 layers, and the third sub-antireflective layer 1023 is 3 layers, and the second sub-antireflective layer 1022 and the third sub-antireflective layer 1023 are alternately arranged sequentially, such as... Figure 2 As shown. If the antireflective layer 102 has 10 layers, then the first sub-antireflective layer 1021 has 1 layer, the second sub-antireflective layer 1022 has 5 layers, and the third sub-antireflective layer 1023 has 4 layers. Furthermore, the second sub-antireflective layer 1022 and the third sub-antireflective layer 1023 are alternately arranged sequentially, as shown. Figure 3 As shown. If the antireflective layer 102 has 11 layers, then the first sub-antireflective layer 1021 has 1 layer, the second sub-antireflective layer 1022 has 5 layers, and the third sub-antireflective layer 1023 has 5 layers. Furthermore, the second sub-antireflective layer 1022 and the third sub-antireflective layer 1023 are alternately arranged sequentially, as shown. Figure 4 As shown.

[0048] In this embodiment, the electric field intensity distribution on the antireflection layer 102 varies depending on the number of antireflection layers 102.

[0049] Specifically, taking an antireflection layer 102 with 8 layers as an example, the distribution of peak electric field intensity in the first cavity surface and the antireflection layer is as follows: Figure 5 As shown. The first cavity surface 1011 of the epitaxial layer 101 includes two peak electric field intensities, denoted as the first peak electric field intensity 104 and the second peak electric field intensity 105, respectively. The first second sub-antireflective layer 1022 includes one peak electric field intensity, denoted as the third peak electric field intensity 106. The first third sub-antireflective layer 1023 includes one peak electric field intensity, denoted as the fourth peak electric field intensity 107, which is also the maximum value among all peak electric field intensities in the first cavity surface and the antireflective layer. The interface region between the second second sub-antireflective layer 1022 and the second third sub-antireflective layer 1023 includes one peak electric field intensity, denoted as the fifth peak electric field intensity 108. The interface region between the third second sub-antireflective layer 1022 and the third third sub-antireflective layer 1023 includes one peak electric field intensity, denoted as the sixth peak electric field intensity 109. The interface region between the fourth layer, the second sub-antireflective layer 1022, and the air includes a peak electric field intensity, denoted as the seventh peak electric field intensity 110.

[0050] In this embodiment, since the electric field intensity of the antireflection layer 102 is periodically oscillating, the maximum value among the multiple peak electric field intensities is located in the central region of the antireflection layer 102, and the electric field intensity gradually decreases from this central region to both sides (the first cavity surface 1011 side and the air side). Therefore, all the above-mentioned peak electric field intensities have the following relationship:

[0051] The fourth peak electric field strength 107 ≥ the second peak electric field strength 105 ≥ the first peak electric field strength 104 ≥ the third valley electric field strength 106 ≥ the fifth valley electric field strength 108 ≥ the sixth peak electric field strength 109 ≥ the seventh peak electric field strength 110.

[0052] Furthermore, the ratio of the fourth peak electric field strength 107 to the second peak electric field strength 105 is a: 1≤a≤2.0, the ratio of the fourth peak electric field strength 107 to the first peak electric field strength 104 is b: 1.2≤b≤1.8, the ratio of the fourth peak electric field strength 107 to the third peak electric field strength 106 is c: 1.5≤c≤2.5, the ratio of the fourth peak electric field strength 107 to the fifth peak electric field strength 108 is d: 1.5≤d≤4, the ratio of the fourth peak electric field strength 107 to the sixth peak electric field strength 109 is e: 2.0≤e≤10, and the ratio of the fourth peak electric field strength 107 to the seventh peak electric field strength 110 is f: 5≤f≤100, and a≤b≤c≤d≤e≤f.

[0053] Meanwhile, the distribution of the valley electric field intensity in the first cavity surface and the antireflection layer remains as follows Figure 5 As shown. A valley electric field intensity, denoted as first valley electric field intensity 111, is included on the first cavity surface 1011 of the epitaxial layer 101. A valley electric field intensity, denoted as second valley electric field intensity 112, is included in the first sub-antireflective layer 1021. A valley electric field intensity, denoted as third valley electric field intensity 113, is included in the first second sub-antireflective layer 1022. A valley electric field intensity, denoted as fourth valley electric field intensity 114, is included in the interface region between the first third sub-antireflective layer 1023 and the second second sub-antireflective layer 1022. A valley electric field intensity, denoted as fifth valley electric field intensity 115, is included in the interface region between the second third sub-antireflective layer 1023 and the third second sub-antireflective layer 1022. The interface region between the third sub-antireflective layer 1023 and the second sub-antireflective layer 1022 of the fourth layer includes a valley electric field intensity, denoted as the sixth valley electric field intensity 116.

[0054] The first layer, third sub-antireflective layer 1023 includes a peak electric field intensity, denoted as the fourth peak electric field intensity 107, which is also the maximum value among all peak electric field intensities in the first cavity surface and the antireflective layer. The interface region between the second layer, second sub-antireflective layer 1022 and the second layer, third sub-antireflective layer 1023 includes a peak electric field intensity, denoted as the fifth peak electric field intensity 108. The interface region between the third layer, second sub-antireflective layer 1022 and the third layer, third sub-antireflective layer 1023 includes a peak electric field intensity, denoted as the sixth peak electric field intensity 109. The interface region between the fourth layer, second sub-antireflective layer 1022 and air includes a peak electric field intensity, denoted as the seventh peak electric field intensity 110.

[0055] In this embodiment, since the electric field intensity of the antireflection layer 102 is periodically oscillating, the maximum value among the multiple peak electric field intensities is located in the central region of the antireflection layer 102, and the electric field intensity gradually decreases from this central region to both sides (the first cavity surface 1011 side and the air side). Therefore, all the aforementioned valley electric field intensities have the following relationship:

[0056] The electric field strength of the sixth valley is 116 ≥ the electric field strength of the fifth valley is 115 ≥ the electric field strength of the fourth valley is 114 ≥ the electric field strength of the third valley is 113 ≥ the electric field strength of the second valley is 112 ≥ the electric field strength of the first valley is 111.

[0057] This embodiment improves the optical field distribution, reduces optical field leakage, enhances the optical field confinement factor, and enhances the beam quality factor by adjusting the electric field intensity distribution of the laser cavity surface and the antireflection layer; it also adjusts the QWOT and distribution of the antireflection layer to reduce the laser diffraction efficiency, reduce the vertical divergence angle, and improve the far-field image quality.

[0058] In some optional embodiments, each sub-antireflection layer of the first cavity surface and the antireflection layer has specific electric field intensity distribution characteristics. Taking an 8-layer antireflection layer as an example, the electric field intensity distribution in the first cavity surface and each sub-antireflection layer is as follows:

[0059] The electric field intensity of the first cavity surface 1011 has a curve distribution of function y1=asin(bx1+c)+d;

[0060] The electric field intensity of the first sub-antireflection layer 1021 has a curve distribution of the function y2=fcos(gx2+h)+i;

[0061] The electric field intensity of the first layer, second sub-antireflection layer 1022 has a curve distribution of function y3=jsin(kx3+m)+n;

[0062] The electric field intensity of the first layer, third sub-antireflection layer 1023 has a function y4=psin(qx4+r)+s curve distribution;

[0063] The electric field intensity of the second sub-antireflection layer 1022 has a function y5=tsin(ux5+v)+w curve distribution;

[0064] The electric field intensity of the second-layer third sub-antireflection layer 1023 has a function y6=Vsin(Wx6+O)+Z curve distribution;

[0065] The electric field intensity of the third layer, the second sub-antireflection layer 1022, has a function y7=Jsin(Kx7+L)+M curve distribution;

[0066] The electric field intensity of the third sub-antireflection layer 1023 has a function y8=Ncos(Px8+L)+Q curve distribution;

[0067] The electric field intensity of the second sub-antireflection layer 1022 of the fourth layer has a curve distribution of function y9=Rsin(Sx9+T)+U;

[0068] Where x1 is the thickness of epitaxial layer 101, x2 is the thickness of the first sub-antireflective layer 1021, x3 is the thickness of the first second sub-antireflective layer 1022, x4 is the thickness of the first third sub-antireflective layer 1023, x5 is the thickness of the second second sub-antireflective layer 1022, x6 is the thickness of the second third sub-antireflective layer 1023, x7 is the thickness of the third second sub-antireflective layer 1022, x8 is the thickness of the third third sub-antireflective layer 1023, x9 is the thickness of the fourth second sub-antireflective layer 1022, U≤Q≤M≤Z≤w≤n≤d≤i≤s, R≤N≤J≤V≤t≤j≤a≤f≤p.

[0069] In some alternative embodiments, the antireflective layer 102 has a reflectivity of 60% to 85% at laser wavelengths from 500 nm to 535 nm. The high reflectivity layer 103 has a reflectivity of 95% to 100% at laser wavelengths from 500 nm to 535 nm.

[0070] In some alternative embodiments, the first sub-antireflective layer 1021 is Al2O3, the second sub-antireflective layer 1022 is Ta2O5 or SiO2, and the third sub-antireflective layer 1023 is SiN. x Or SiO2.

[0071] Specifically, each material has a refractive index η. The refractive index η is the ratio of the speed of light in a vacuum to the speed of light in a medium. The wavelength of light in the medium is given by the equation λ = λ0 / η, where λ0 is the wavelength of light in a vacuum. QWOT = λ0 / 4η is used to determine the quarter wavelength within a single layer of the medium. Therefore, in this embodiment, the quarter wavelength QWOT of the first sub-antireflective layer 102, the second sub-antireflective layer 1022, and the third sub-antireflective layer 1023 made of different materials will also differ. This embodiment will still take an antireflective layer 102 with 8 layers as an example for specific explanation.

[0072] When the number of antireflective layers 102 is 8, the second sub-antireflective layer 1022 is Ta2O5, and the third sub-antireflective layer 1023 is SiO2, the quarter-wavelengths of the first sub-antireflective layer 1021, the first second sub-antireflective layer 1022, the first third sub-antireflective layer 1023, the second second sub-antireflective layer 1022, the second third sub-antireflective layer 1023, the third second sub-antireflective layer 1022, the third third sub-antireflective layer 1023, and the fourth second sub-antireflective layer 1022 are 0.8 to 1.2, 1.9 to 2.3, 1.5 to 1.9, and 0.8 to 1, respectively. 2. 0.8 to 1.2, 0.8 to 1.2, 0.8 to 1.2, 0.8 to 1.2, 0.8 to 1.2, the quarter wavelength of the first sub-antireflective layer 1021 ≤ the quarter wavelength of the fourth layer second sub-antireflective layer 1022 ≤ the quarter wavelength of the third layer second sub-antireflective layer 1022 ≤ the quarter wavelength of the second layer second sub-antireflective layer 1022 ≤ the quarter wavelength of the third layer third sub-antireflective layer 1023 ≤ the quarter wavelength of the second layer third sub-antireflective layer 1023 ≤ the quarter wavelength of the first layer third sub-antireflective layer 1023 ≤ the quarter wavelength of the first layer second sub-antireflective layer 1022.

[0073] In some optional embodiments, the epitaxial layer 101 includes, from bottom to top, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, and an upper confinement layer, such as... Figure 6 As shown. The epitaxial layer 101 is any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond.

[0074] In some alternative embodiments, the substrate 100 includes sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, graphene, and sapphire / SiN. x Sapphire / SiO2 / SiN x Composite substrate, sapphire / SiN x Any one of the following: SiO2 composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

[0075] The table below compares the parameters of a conventional gallium nitride (GaN)-based semiconductor laser chip with those proposed in this embodiment, including stimulated emission quantum efficiency, threshold current density, confinement factor, internal optical loss, beam quality factor, and focused spot resolution. This table also highlights the differences between the conventional GaN-based semiconductor laser chip and the GaN-based semiconductor laser chip proposed in this embodiment.

[0076]

[0077] As can be seen, the gallium nitride-based semiconductor laser chip element proposed in this embodiment improves the stimulated emission quantum efficiency and confinement factor, reduces the threshold current density, internal optical loss and beam quality factor, and significantly improves the focused spot resolution compared with traditional semiconductor laser chips. It has obvious advantages compared with traditional gallium nitride-based semiconductor laser chip elements.

[0078] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A gallium nitride-based semiconductor laser chip element, comprising a substrate and an epitaxial layer, wherein the epitaxial layer is disposed on the upper layer of the substrate, characterized in that, The left and right sides of the epitaxial layer are the first cavity surface and the second cavity surface, respectively. The laser is emitted along the direction from the second cavity surface to the first cavity surface. The surface of the first cavity surface is coated with an anti-reflection layer, and the surface of the second cavity surface is coated with a high-reflection layer. The anti-reflection layer includes a first sub-anti-reflection layer sequentially coated on the surface of the first cavity surface, and a periodic structure formed by alternating second and third sub-anti-reflection layers. The electric field intensity of the simulated optical field distribution of the anti-reflection layer is a periodic oscillating distribution. The anti-reflection layer includes multiple peak electric field intensities and multiple valley electric field intensities. The maximum value of the multiple peak electric field intensities is located in the central region of the anti-reflection layer, and the electric field intensity gradually decreases from the central region to both sides.

2. The gallium nitride-based semiconductor laser chip element according to claim 1, characterized in that, The antireflective layer has a reflectivity of 60% to 85% at laser wavelengths of 500 nm to 535 nm, and the high reflectivity layer has a reflectivity of 95% to 100% at laser wavelengths of 500 nm to 535 nm.

3. The gallium nitride-based semiconductor laser chip element according to claim 1, characterized in that, The antireflective layer has 6 to 15 layers.

4. The gallium nitride-based semiconductor laser chip element according to claim 3, characterized in that, The antireflective layer has eight layers and includes five peak electric field intensities. The first cavity surface includes two peak electric field intensities. The first and second peak electric field intensities are located in the first cavity surface. The third peak electric field intensity is located in the first layer of the second sub-antireflective layer. The fourth peak electric field intensity is located in the first layer of the third sub-antireflective layer, and the fourth peak electric field intensity is the maximum value among the peak electric field intensities. The fifth peak electric field intensity is located in the interface region between the second layer of the second sub-antireflective layer and the second layer of the third sub-antireflective layer. The sixth peak electric field intensity is located in the interface region between the third layer of the second sub-antireflective layer and the third layer of the third sub-antireflective layer. The seventh peak electric field intensity is located in the interface region between the fourth layer of the second sub-antireflective layer and the air. The fourth peak electric field intensity is greater than or equal to the second peak electric field intensity, the first peak electric field intensity, the third valley electric field intensity, the fifth valley electric field intensity, the sixth peak electric field intensity, and the seventh peak electric field intensity.

5. The gallium nitride-based semiconductor laser chip element according to claim 4, characterized in that, The ratio of the fourth peak electric field intensity to the second peak electric field intensity is a: 1≤a≤2.0, the ratio of the fourth peak electric field intensity to the first peak electric field intensity is b: 1.2≤b≤1.8, the ratio of the fourth peak electric field intensity to the third peak electric field intensity is c: 1.5≤c≤2.5, the ratio of the fourth peak electric field intensity to the fifth peak electric field intensity is d: 1.5≤d≤4, the ratio of the fourth peak electric field intensity to the sixth peak electric field intensity is e: 2.0≤e≤10, and the ratio of the fourth peak electric field intensity to the seventh peak electric field intensity is f: 5≤f≤100, and a≤b≤c≤d≤e≤f.

6. The gallium nitride-based semiconductor laser chip element according to claim 3, characterized in that, The antireflective layer has eight layers and includes five valley electric field intensities. The first cavity surface includes one valley electric field intensity. The first valley electric field intensity is located in the first cavity surface. The second valley electric field intensity is located in the first sub-antireflective layer. The third valley electric field intensity is located in the first layer second sub-antireflective layer. The fourth valley electric field intensity is located in the interface region between the first layer third sub-antireflective layer and the second layer second sub-antireflective layer. The fifth valley electric field intensity is located in the interface region between the second layer third sub-antireflective layer and the third layer second sub-antireflective layer. The sixth valley electric field intensity is greater than or equal to the fifth valley electric field intensity, the fourth valley electric field intensity, the third valley electric field intensity, the second valley electric field intensity, and the first valley electric field intensity.

7. The gallium nitride-based semiconductor laser chip element according to claim 3, characterized in that, The first sub-antireflective layer is Al2O3, the second sub-antireflective layer is Ta2O5 or SiO2, and the third sub-antireflective layer is SiN. x Or SiO2.

8. The gallium nitride-based semiconductor laser chip element according to claim 3, characterized in that, When the number of antireflective layers is 8, the second sub-antireflective layer is Ta2O5, and the third sub-antireflective layer is SiO2, the quarter-wavelengths of the first sub-antireflective layer, the first second sub-antireflective layer, the first third sub-antireflective layer, the second second sub-antireflective layer, the second third sub-antireflective layer, the third second sub-antireflective layer, the third third sub-antireflective layer, and the fourth second sub-antireflective layer are 0.8 to 1.2, 1.9 to 2.3, 1.5 to 1.9, 0.8 to 1.2, 0.8 to 1.2, 0.8 to 1.2, 0.8 to 1.2, 0.8 to 1.2, and 0.8 to 1.2, respectively. The quarter-wavelength of the first sub-antireflective layer ≤ the quarter-wavelength of the fourth second sub-antireflective layer ≤ the quarter-wavelength of the third second sub-antireflective layer ≤ the quarter-wavelength of the second second sub-antireflective layer ≤ the quarter-wavelength of the third third sub-antireflective layer ≤ the quarter-wavelength of the first third sub-antireflective layer ≤ the quarter-wavelength of the first second sub-antireflective layer.

9. The gallium nitride-based semiconductor laser chip element according to claim 1, characterized in that, The epitaxial layer comprises, from bottom to top, a lower confinement layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, and an upper confinement layer. The epitaxial layer is any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond. The substrates include sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrates, Mo, TiW, CuW, Cu, sapphire / AlN composite substrates, diamond, graphene, and sapphire / SiN. x Sapphire / SiO2 / SiN x Composite substrate, sapphire / SiN x Any one of the following: SiO2 composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.

Images