A gallium arsenide-based superluminescent diode and a method of manufacturing the same

Abstract

The application relates to a gallium arsenide-based super-radiation light-emitting diode and a preparation method thereof, and mainly solves the technical problem that when a cavity surface is coated with an anti-reflection film in combination with a non-pumping absorption zone and a curved waveguide, an inclined waveguide, a tapered waveguide and other technologies to suppress light oscillation in a resonance cavity, resonance gain still exists, which has a negative impact on the power and other performances of the gallium arsenide-based super-radiation light-emitting diode. The gallium arsenide-based super-radiation light-emitting diode comprises a substrate layer, an epitaxial layer arranged on the substrate layer, and a metal layer arranged on the epitaxial layer; the metal layer is in a straight line type structure; the light-out surface and the back-light surface of the substrate layer and the epitaxial layer are arranged in parallel to each other, and the light-out surface and the back-light surface are both arranged in an inclined manner along the direction from the back-light surface to the light-out surface; an obtuse angle formed by the light-out surface and the back-light surface with a horizontal direction is defined as an inclination angle alpha, and the value of alpha is 100-110 degrees; the light-out surface is coated with an AR reflection film, and the reflectivity is 0.5-50%; and the back-light surface is coated with an HR reflection film, and the reflectivity is greater than 90%.

Description

Technical Field

[0001] This invention relates to a superluminescent diode and its fabrication method, specifically to a gallium arsenide-based superluminescent diode and its fabrication method. Background Technology

[0002] Superluminescent diodes (SLDs) are optical emitting devices that amplify spontaneously emitted photons through stimulated emission as they propagate within a cavity. Their optical properties fall between those of semiconductor lasers (LDs) and light-emitting diodes (LEDs). Compared to semiconductor lasers, SLDs have a wider emission spectrum and a shorter coherence length, which can significantly reduce noise caused by Rayleigh scattering and nonlinear optical Kerr effects in optical fibers, as well as mode noise in fiber transmission. Compared to conventional LEDs, SLDs have higher output power, smaller divergence angle, higher coupling efficiency, and faster response speed.

[0003] Gallium arsenide-based superluminescent diodes (SEDs) have been widely used in fields such as fiber optic gyroscopes, optical time domain reflectometers (OTDRs), optical coherence tomography, inertial confinement fusion, and optical processing technology due to their wide spectrum, high power, low noise, and small divergence angle.

[0004] Existing gallium arsenide-based superluminescent diodes typically employ cavity surface antireflection coatings combined with unpumped absorption regions and techniques such as bent waveguides, tilted waveguides, and tapered waveguides to suppress optical oscillations within the resonant cavity in order to achieve superluminescence. However, when using the above techniques to suppress optical oscillations within the resonant cavity, resonant gain still exists, negatively impacting the diode's power and other performance characteristics. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problem that when existing gallium arsenide-based superluminescent diodes use cavity surface anti-reflection films combined with non-pump absorption regions and techniques such as bent waveguides, tilted waveguides, and tapered waveguides to suppress optical oscillations in the resonant cavity, there is still a resonant gain that negatively affects their power and other performance characteristics. The invention provides a gallium arsenide-based superluminescent diode and its fabrication method.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A gallium arsenide-based superluminescent light-emitting diode, characterized in that it comprises a substrate layer, an epitaxial layer disposed on the substrate layer, and a metal layer disposed on the epitaxial layer;

[0008] The metal layer has a linear structure. Compared with the curved structure, the linear structure can improve the carrier utilization efficiency and thus improve the power of the diode.

[0009] The light-emitting surface and the back-light surface of the substrate layer and the epitaxial layer are arranged parallel to each other. Both the light-emitting surface and the back-light surface are inclined along the direction from the back-light surface to the light-emitting surface. The obtuse angle between the light-emitting surface and the back-light surface and the horizontal direction is defined as the inclination angle α, and the value of α is 100° to 110°.

[0010] The light-emitting surface is coated with an AR reflective film with a reflectivity of 0.5% to 50%; the backlight surface is coated with an HR reflective film with a reflectivity greater than 90%.

[0011] Furthermore, the tilt angle α is 105°.

[0012] Furthermore, the epitaxial layer includes a buffer layer, a first confinement layer, a first waveguide layer, an active region, a second waveguide layer, and a second confinement layer arranged sequentially.

[0013] The buffer layer is connected to the substrate layer, and the metal layer is disposed on the second confinement layer.

[0014] Furthermore, the buffer layer is made of GaAs and has a thickness of 0.5-1 μm;

[0015] The first and second confinement layers have the same structure and are both made of Al. x Ga 1-x The values ​​of As and X range from 0.1 to 0.8, and the thicknesses range from 0.1 to 0.5 μm.

[0016] The first waveguide layer and the second waveguide layer have the same structure and are both made of Al. Y Ga 1-Y The values ​​of As and Y range from 0.1 to 0.5, and the thicknesses range from 0.1 to 1.0 μm.

[0017] Furthermore, the active region includes a quantum trap layer and two barrier layers;

[0018] The two barrier layers are respectively disposed on the sides of the quantum well layer, near and far from the substrate layer.

[0019] Furthermore, the active region includes a quantum well layer and two barrier layers;

[0020] The two barrier layers are respectively disposed on the sides of the quantum well layer, near and far from the substrate layer.

[0021] Furthermore, the quantum well layer is a structure consisting of one quantum well or a combination of multiple quantum wells.

[0022] Furthermore, the materials of the quantum well layer and the barrier layer are GaAs and Al. x Ga 1-x As、Al x Ga 1-x In y As1-y Or Al x Ga 1-x As y P 1-y .

[0023] Meanwhile, this invention also provides a method for fabricating a gallium arsenide-based superluminescent diode, characterized by the following steps:

[0024] Step 1: Select GaAs material with crystal orientation 100 and bias angle 111 of 10° to 20° as the substrate layer;

[0025] Step 2: Using epitaxial growth technology, an epitaxial layer is grown on the substrate along its crystal orientation to form an epitaxial wafer;

[0026] Step 3: Perform photolithography, etching, metallization, and cleavage sequentially on the epitaxial wafer;

[0027] Step 4: Fabricate a linear metal layer on the epitaxial layer;

[0028] Step 5: Use the cleavage surfaces at both ends of the epitaxial wafer as the light-emitting surface and the back-light surface, respectively. Deposit an AR reflective film on the light-emitting surface with a reflectivity of 0.5-50%; deposit an HR reflective film on the back-light surface with a reflectivity greater than 90%.

[0029] Step 6: Complete the fabrication of the superluminescent diode.

[0030] Furthermore, in step 1, the substrate layer is Si-doped with a doping concentration greater than 1*10E18cm⁻¹. -3 ;

[0031] In step 2, the following layers are grown sequentially on the substrate along its crystal orientation using epitaxial growth technology: buffer layer, first confinement layer, first waveguide layer, active region, second waveguide layer, and second confinement layer.

[0032] Furthermore, in step 2, the epitaxial growth technique employed is MOCVD epitaxial growth technology;

[0033] In step 4, a linear metal layer is fabricated on the epitaxial layer using a metal evaporation process.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] This invention employs a symmetrical non-perpendicular light-emitting surface and a back-light-receiving surface, setting the light-emitting surface and the back-light-receiving surface as inclined surfaces. This prevents the light path within the epitaxial layer from returning along the original path, thereby suppressing optical oscillations within the epitaxial layer, further reducing the optical resonance gain, and improving the radiative recombination efficiency of the diode. Furthermore, by setting the metal layer as a straight line, the utilization efficiency of charge carriers is improved, thereby enhancing the photoelectric conversion efficiency and ultimately increasing the power of the diode. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a gallium arsenide-based superluminescent diode according to the present invention;

[0037] Figure 2 yes Figure 1 Top view;

[0038] Figure 3 This is a schematic diagram of the substrate layer and epitaxial layer in an embodiment of a gallium arsenide-based superluminescent diode of the present invention (the metal layer is not shown in the figure).

[0039] In the figure, 1-substrate layer, 2-epitaxy layer, 21-metal layer, 22-buffer layer, 23-first confinement layer, 24-first waveguide layer, 25-active region, 26-second waveguide layer, 27-second confinement layer, 3-light-emitting surface, 4-backlight surface, 5-AR reflective film, 6-HR reflective film. Detailed Implementation

[0040] To make the objectives, advantages, and features of the present invention clearer, the following detailed description of a gallium arsenide-based superluminescent diode and its fabrication method, in conjunction with the accompanying drawings and specific embodiments, will further illustrate the present invention. The advantages and features of the present invention will become clearer according to the following specific embodiments. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, used only to facilitate and clarify the explanation of the embodiments of the present invention; furthermore, the structures shown in the drawings are often part of the actual structures.

[0041] like Figures 1-3 As shown, this invention discloses a gallium arsenide-based superluminescent diode, comprising a substrate layer 1, an epitaxial layer 2, and a metal layer 21. The epitaxial layer 2 includes a buffer layer 22, a first confinement layer 23, a first waveguide layer 24, an active region 25, a second waveguide layer 26, and a second confinement layer 27, sequentially disposed thereon. The buffer layer 22 is connected to the substrate layer 1, and the metal layer 21 is disposed on the second confinement layer 27. Figure 2 As shown, metal layer 21 has a linear structure.

[0042] like Figure 3As shown, in a preferred embodiment of the present invention, the buffer layer 22 is made of GaAs and has a thickness of 0.5–1 μm; the first limiting layer 23 and the second limiting layer 27 have the same structure and are both made of Al. x Ga 1-x The values ​​of As and X range from 0.1 to 0.8, and their thicknesses range from 0.1 to 0.5 μm. The first waveguide layer 24 and the second waveguide layer 26 have the same structure and are both made of Al. Y Ga 1-Y The as and Y atoms range from 0.1 to 0.5 μm, and their thicknesses range from 0.1 to 1.0 μm. The active region 25 includes a quantum well layer and two barrier layers. The quantum well layer is a structure consisting of one or more quantum wells, and the two barrier layers are respectively located on the sides of the quantum well layer, near and far from the substrate layer 1. The materials of the quantum well layer and the barrier layers are GaAs and Al. x Ga 1-x As、Al x Ga 1-x In y As 1-y Or Al x Ga 1-x As y P 1-y The materials for the quantum well layer and the barrier layer can be selected from the above materials, and the two materials can be the same or different.

[0043] like Figure 1 As shown, the light-emitting surface 3 and the back-light surface 4 of the substrate layer 1 and the epitaxial layer 2 are arranged parallel to each other. Both the light-emitting surface 3 and the back-light surface 4 are inclined along the direction from the back-light surface 4 to the light-emitting surface 3. The obtuse angle formed by the light-emitting surface 3 and the back-light surface 4 with the horizontal direction is defined as the inclination angle α, and the value of α is 100° to 110°. In a preferred embodiment of the present invention, the inclination angle α is set to 105°. The light-emitting surface 3 is coated with an AR reflective film 5 (anti-reflection film) with a reflectivity of 0.5 to 50%. The back-light surface 4 is coated with an HR reflective film 6 (high reflectivity film) with a reflectivity greater than 90%. Through the above design, a resonant cavity surface inclined at 105° can be formed. Due to the existence of this inclined surface, the light path in the epitaxial layer 2 cannot return along the original path, thus avoiding the occurrence of optical resonance gain.

[0044] This invention discloses a method for fabricating a gallium arsenide-based superluminescent diode, comprising the following steps:

[0045] Step 1: Select GaAs material with crystal orientation 100 and bias angle 111 of 10° to 20° as substrate layer 1; substrate layer 1 is Si doped with a doping concentration greater than 1*10E18cm-3.

[0046] Step 2: Using MOCVD epitaxial growth technology (a novel vapor phase epitaxial growth technology) or other epitaxial growth technologies, grow an epitaxial layer 2 along its crystal orientation on the substrate layer 1 to form an epitaxial wafer;

[0047] Specifically, the epitaxial growth is performed in the following order: buffer layer 22, first confinement layer 23, first waveguide layer 24, active region 25, second waveguide layer 26, and second confinement layer 27.

[0048] Step 3: Perform photolithography, etching, metallization, and cleavage sequentially on the epitaxial wafer;

[0049] Step 4: Fabricate a linear metal layer 21 on the epitaxial layer 2 using a metal evaporation process;

[0050] Step 5: Use the cleavage surfaces at both ends of the epitaxial wafer as the light-emitting surface 3 and the back-light surface 4, respectively; deposit an AR reflective film 5 on the light-emitting surface 3 with a reflectivity of 0.5-50%; deposit an HR reflective film 6 on the back-light surface 4 with a reflectivity greater than 90%.

[0051] Step 6: Complete the fabrication of the superluminescent diode.

Claims

1. A gallium arsenide based superluminescent diode, characterized by: It includes a substrate layer (1), an epitaxial layer (2) disposed on the substrate layer (1), and a metal layer (21) disposed on the epitaxial layer (2); The metal layer (21) has a linear structure; The light-emitting surface (3) and the back-light surface (4) of the substrate layer (1) and the epitaxial layer (2) are arranged parallel to each other. The light-emitting surface (3) and the back-light surface (4) are both inclined along the direction from the back-light surface (4) to the light-emitting surface (3). The obtuse angle between the light-emitting surface (3) and the back-light surface (4) and the horizontal direction is defined as the inclination angle α, and the value of α is 100°~110°. The light-emitting surface (3) is coated with an AR reflective film (5) with a reflectivity of 0.5-50%; the backlight surface (4) is coated with an HR reflective film (6) with a reflectivity greater than 90%. The epitaxial layer (2) includes a buffer layer (22), a first confinement layer (23), a first waveguide layer (24), an active region (25), a second waveguide layer (26), and a second confinement layer (27) arranged sequentially. The buffer layer (22) is connected to the substrate layer (1), and the metal layer (21) is disposed on the second confinement layer (27).

2. A gallium arsenide based superluminescent diode according to claim 1, wherein: The tilt angle α is 105°.

3. A gallium arsenide based superluminescent diode according to claim 1 or 2, wherein: The buffer layer (22) is made of GaAs and has a thickness of 0.5-1μm; The first limiting layer (23) and the second limiting layer (27) have the same structure and are both made of Al. x Ga 1-x The values ​​of As and X range from 0.1 to 0.8, and the thicknesses range from 0.1 to 0.5 μm. The first waveguide layer (24) and the second waveguide layer (26) have the same structure and are both made of Al. Y Ga 1-Y The values ​​of As and Y range from 0.1 to 0.5, and the thicknesses range from 0.1 to 1.0 μm.

4. A gallium arsenide based superluminescent diode according to claim 3, wherein: The active region (25) includes a quantum well layer and two barrier layers; The two barrier layers are respectively disposed on the sides of the quantum well layer, near and far from the substrate layer (1).

5. A gallium arsenide-based superluminescent light-emitting diode according to claim 4, characterized in that: The quantum well layer is a structure consisting of one quantum well or a combination of multiple quantum wells.

6. A gallium arsenide based superluminescent diode according to claim 5, wherein: The quantum well layer and the barrier layer are made of GaAs and Al. x Ga 1-x As、Al x Ga 1-x In y As 1-y Or Al x Ga 1-x As y P 1-y .

7. A method for fabricating a GaAs-based superluminescent diode, for fabricating a GaAs-based superluminescent diode according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: Select GaAs material with crystal orientation 100 and bias angle of 111 of 10° to 20° as substrate layer (1); Step 2: Using epitaxial growth technology, an epitaxial layer (2) is grown on the substrate layer (1) along its crystal orientation to form an epitaxial wafer; Step 3: Perform photolithography, etching, metallization, and cleavage sequentially on the epitaxial wafer; Step 4: Fabricate a linear metal layer (21) on the epitaxial layer (2); Step 5: Take the cleavage surfaces at both ends of the epitaxial wafer as the light-emitting surface (3) and the back-light surface (4), respectively. Deposit an AR reflective film (5) on the light-emitting surface (3) with a reflectivity of 0.5-50%; deposit an HR reflective film (6) on the back-light surface (4) with a reflectivity greater than 90%. Step 6: Complete the fabrication of the superluminescent diode.

8. The method for fabricating a gallium arsenide-based superluminescent diode according to claim 7, characterized in that: In step 1, the substrate layer (1) is Si-doped with a doping concentration greater than 1*10E18cm-3; In step 2, the following layers are grown sequentially on the substrate layer (1) along its crystal orientation using epitaxial growth technology: buffer layer (22), first confinement layer (23), first waveguide layer (24), active region (25), second waveguide layer (26), and second confinement layer (27).

9. The method of claim 8, wherein the GaAs-based SLED is prepared by the steps of: In step 2, the epitaxial growth technology used is MOCVD epitaxial growth technology; ​ In step 4, a linear metal layer (21) is fabricated on the epitaxial layer (2) by means of a metal evaporation process.

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