A GaN-based laser diode and a method of fabricating the same

Abstract

The application provides a GaN-based laser diode and a manufacturing method thereof. The GaN-based laser diode comprises, from top to bottom, a P-GaN layer, a P-cladding layer, a P-waveguide layer, a quantum well, an N-waveguide layer, an N-cladding layer and an N-GaN layer. The P-GaN layer is located at the middle part of the P-cladding layer and forms a ridge structure, and the width of the ridge structure is smaller than the width of the P-cladding layer. An insulating layer is arranged on the P-cladding layer at the peripheral area of the ridge structure. A hole with an opening facing upward is arranged on the contact surface between the ridge structure and the insulating layer. A conductive layer is arranged on the ridge structure and the hole. The P electrode is arranged on the conductive layer, and the N electrode is arranged on the N-GaN layer. The GaN-based laser diode can form a higher light confining effect to meet higher use requirements.

Description

Technical Field

[0001] This application relates to the field of diode fabrication, and more particularly to a GaN-based laser diode and its fabrication method. Background Technology

[0002] Currently, most existing GaN-based laser diode structures use insulating materials such as SiO2, with a refractive index typically around 1.46, to achieve good light confinement. The P-contact layer mainly uses a Pd metal layer as both a mask and a contact, such as... Figure 1 As shown. Current contact layers are mainly metals with high refractive index and absorption; while transparent low-refractive-index materials are insulating materials and cannot form ohmic contacts; for narrow-ridge lasers to achieve stable ohmic contacts by covering the ridge sidewalls with insulating materials, the requirements for process and equipment precision are extremely high.

[0003] Furthermore, while the current GaN-based laser diode structure can meet the needs of most common scenarios, it still has limitations in light confinement for some demanding applications. Therefore, it is necessary to modify the GaN-based laser diode structure to achieve a higher level of light confinement. Summary of the Invention

[0004] To address one of the aforementioned technical problems, this invention provides a GaN-based laser diode and its fabrication method.

[0005] A first aspect of this invention provides a GaN-based laser diode, comprising a P-electrode, a P-GaN layer, a P-Cladding layer, a P-waveguide layer, a quantum well, an N-waveguide layer, an N-Cladding layer, an N-GaN layer, and an N-electrode. The P-GaN layer, P-Cladding layer, P-waveguide layer, quantum well, N-waveguide layer, N-Cladding layer, and N-GaN layer are arranged sequentially from top to bottom. The P-GaN layer is located in the middle of the P-Cladding layer and forms a ridge structure, and the width of the ridge structure is smaller than the width of the P-Cladding layer. An insulating layer is disposed on the P-Cladding layer in the area surrounding the ridge structure. An upward-facing hole is formed on the contact surface between the ridge structure and the insulating layer. A conductive layer is disposed on the ridge structure and the hole. The P-electrode is disposed on the conductive layer, and the N-electrode is disposed on the N-GaN layer.

[0006] Preferably, the bottom of the hole extends into the P-Cladding layer.

[0007] Preferably, the ridge structure has a width of 0.5 μm to 5 μm and a height of 200 nm to 800 nm.

[0008] Preferably, the insulating layer is a SiO2 insulating layer or a SiN insulating layer.

[0009] Preferably, the conductive layer is an ITO conductive layer.

[0010] A second aspect of this invention provides a method for fabricating a GaN-based laser diode, the method comprising:

[0011] A corrosion-resistant metal was used as a mask to fabricate the P-GaN layer into a ridge-like structure.

[0012] An insulating layer is grown on the ridge structure, the mask, and the P-Cladding layer;

[0013] Etching is performed at the contact points between the sidewalls of the ridge structure and the insulating layer to form holes;

[0014] Etch the mask;

[0015] A conductive layer is deposited on the ridge structure and the holes;

[0016] A P-electrode is fabricated on the conductive layer, and an N-electrode is fabricated on the N-GaN layer to form a GaN-based laser diode.

[0017] Preferably, the bottom of the hole formed when etching the contact position between the sidewall of the ridge structure and the insulating layer extends into the P-Cladding layer.

[0018] Preferably, the ridge structure has a width of 0.5 μm to 5 μm and a height of 200 nm to 800 nm.

[0019] Preferably, the insulating layer is a SiO2 insulating layer or a SiN insulating layer.

[0020] Preferably, the conductive layer is an ITO conductive layer.

[0021] The beneficial effects of this invention are as follows: The GaN-based laser diode and its fabrication method proposed in this invention form a ridge-like structure with a P-GaN layer. Holes are formed on the sides of this ridge-like structure and filled with a low-refractive-index conductive layer to cover the ridge-like structure and the holes at all angles. Gallium nitride (GaN) material has a refractive index of approximately 2.4. The sidewalls are covered by an insulating layer with a refractive index lower than that of GaN material, achieving good light confinement. However, at the top and corner positions, if metal contacts are used directly, many of the contact metals have a refractive index greater than 2, resulting in high absorption and refractive index, leading to poor light confinement. This embodiment uses a conductive layer with a refractive index lower than that of the metal, resulting in zero absorption of visible light. This achieves both good ohmic contact and higher light confinement to meet higher application requirements. Attached Figure Description

[0022] 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:

[0023] Figure 1 This is a schematic diagram of the structure of an existing GaN-based laser diode;

[0024] Figure 2 This is a schematic diagram of the GaN-based laser diode described in Embodiment 1 of the present invention;

[0025] Figure 3 This is a schematic diagram of the GaN-based laser diode described in Embodiment 2 of the present invention;

[0026] Figures 4 to 8 This is a schematic diagram illustrating the fabrication process of the GaN-based laser diode as described in Embodiments 1 and 2 of the present invention.

[0027] Figure label:

[0028] 1. P-electrode, 2. P-GaN layer, 3. P-Cladding layer, 4. P-waveguide layer, 5. Quantum well, 6. N-waveguide layer, 7. N-Cladding layer, 8. N-GaN layer, 9. N-electrode, 10. Mask, 11. Insulating layer, 12. Hole, 13. Conductive layer. Detailed Implementation

[0029] 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.

[0030] Example 1

[0031] like Figure 2 As shown, this embodiment proposes a GaN-based laser diode, which specifically includes a P-electrode 1, a P-GaN layer 2, a P-Cladding layer 3, a P-waveguide layer 4, a quantum well 5, an N-waveguide layer 6, an N-Cladding layer 7, an N-GaN layer 8, and an N-electrode 9. The P-GaN layer 2, P-Cladding layer 3, P-waveguide layer 4, quantum well 5, N-waveguide layer 6, N-Cladding layer 7, and N-GaN layer 8 are arranged sequentially from top to bottom.

[0032] Furthermore, the P-GaN layer 2 is located in the middle of the P-Cladding layer 3 and forms a ridge structure, the width of which is smaller than the width of the P-Cladding layer 3. An insulating layer 11 is disposed on the P-Cladding layer 3 in the area surrounding the ridge structure. An upward-facing hole 12 is formed at the contact surface between the ridge structure and the insulating layer 11. A conductive layer 13 is disposed on the ridge structure and the hole 12. A P electrode 1 is disposed on the conductive layer 13, and an N electrode 9 is disposed on the N-GaN layer 8. The width of the ridge structure is 0.5 μm to 5 μm, and the height is 200 nm to 800 nm. The insulating layer 11 is a SiO2 insulating layer 11 or a SiN insulating layer 11. The conductive layer 13 is an ITO conductive layer 13.

[0033] Example 2

[0034] like Figure 3 As shown, this embodiment proposes a GaN-based laser diode, which specifically includes a P-electrode 1, a P-GaN layer 2, a P-Cladding layer 3, a P-waveguide layer 4, a quantum well 5, an N-waveguide layer 6, an N-Cladding layer 7, an N-GaN layer 8, and an N-electrode 9. The P-GaN layer 2, P-Cladding layer 3, P-waveguide layer 4, quantum well 5, N-waveguide layer 6, N-Cladding layer 7, and N-GaN layer 8 are arranged sequentially from top to bottom.

[0035] Furthermore, the P-GaN layer 2 is located in the middle of the P-Cladding layer 3 and forms a ridge structure, the width of which is smaller than the width of the P-Cladding layer 3. An insulating layer 11 is disposed on the P-Cladding layer 3 around the ridge structure. An upward-facing hole 12 is formed at the contact surface between the ridge structure and the insulating layer 11, and the bottom of the hole 12 extends into the P-Cladding layer 3. A conductive layer 13 is disposed on the ridge structure and the hole 12. A P electrode 1 is disposed on the conductive layer 13, and an N electrode 9 is disposed on the N-GaN layer 8. The width of the ridge structure is 0.5 μm to 5 μm, and the height is 200 nm to 800 nm. The insulating layer 11 is a SiO2 insulating layer 11 or a SiN insulating layer 11. The conductive layer 13 is an ITO conductive layer 13.

[0036] Example 3

[0037] like Figure 2 , Figures 4 to 7 As shown, this embodiment proposes a method for fabricating a GaN-based laser diode. The structure of the GaN-based laser diode can be referred to the description in Embodiment 1, and will not be repeated here. Specifically, the fabrication method includes the following steps:

[0038] A corrosion-resistant metal is used as the mask 10 to fabricate the P-GaN layer 2 into a ridge structure;

[0039] An insulating layer 11 is grown on the ridge structure, mask 10 and P-Cladding layer 3;

[0040] Etching is performed at the contact points between the sidewalls of the ridge structure and the insulating layer 11 to form holes 12;

[0041] Etch mask 10;

[0042] A conductive layer 13 is deposited on the P-GaN layer 2 and the hole 12;

[0043] A P-electrode 1 is fabricated on the conductive layer 13, and an N-electrode 9 is fabricated on the N-GaN layer 8 to form a GaN-based laser diode.

[0044] Specifically, a metal with corrosion resistance, such as Pd, Pt, or Ni, is used as the mask 10 to fabricate a ridge structure in the P-GaN layer 2 with a width of 0.5 μm to 5 μm and a height of 200 nm to 800 nm, such as... Figure 4 and Figure 5 As shown. A SiO2 or SiN insulating layer 11 is grown, covering the entire ridge structure, mask 10, and P-Cladding layer 3, as shown. Figure 6As shown, a self-aligned process was used to clean the photoresist on the ridge structure. Then, gases such as CF4 or CH3F were used to etch windows in the insulating layer 11, forming V-shaped holes 12 on both sides, as shown. Figure 7 As shown. The mask 10 is then etched away using acid or a strong oxide. An ITO conductive layer 13 is deposited on the ridge structure and holes 12, fully covering the ridge structure and holes 12, and then annealed. Finally, a P-electrode 1 is fabricated on the conductive layer 13, and an N-electrode 9 is fabricated on the N-GaN layer 8. The material is then split into strips, a cavity film is deposited, and a GaN-based laser diode is formed, as shown. Figure 2 As shown.

[0045] Example 4

[0046] like Figures 3 to 6 , Figure 8 As shown, this embodiment proposes a method for fabricating a GaN-based laser diode. The structure of the GaN-based laser diode can be referred to the description in Embodiment 2, and will not be repeated here. Specifically, the fabrication method includes the following steps:

[0047] A corrosion-resistant metal is used as the mask 10 to fabricate the P-GaN layer 2 into a ridge structure;

[0048] An insulating layer 11 is grown on the ridge structure, mask 10 and P-Cladding layer 3;

[0049] The contact position between the sidewall of the ridge structure and the insulating layer 11 is etched to form a hole 12, and the bottom of the hole 12 extends into the P-Cladding layer 3;

[0050] Etch mask 10;

[0051] A conductive layer 13 is deposited on the P-GaN layer 2 and the hole 12;

[0052] A P-electrode 1 is fabricated on the conductive layer 13, and an N-electrode 9 is fabricated on the N-GaN layer 8 to form a GaN-based laser diode.

[0053] Specifically, a metal with corrosion resistance, such as Pd, Pt, or Ni, is used as the mask 10 to fabricate a ridge structure in the P-GaN layer 2 with a width of 0.5 μm to 5 μm and a height of 200 nm to 800 nm, such as... Figure 4 and Figure 5 As shown. A SiO2 or SiN insulating layer 11 is grown, covering the entire ridge structure, mask 10, and P-Cladding layer 3, as shown. Figure 6As shown, a self-aligned process is used to clean the photoresist on the ridge structure. Then, gases such as CF4 or CH3F are used to etch windows in the insulating layer 11, forming V-shaped holes 12 on both sides. The bottom of the holes 12 extends into the P-Cladding layer 3, as shown. Figure 8 As shown. The mask 10 is then etched away using acid or a strong oxide. An ITO conductive layer 13 is deposited on the ridge structure and holes 12, fully covering the ridge structure and holes 12, and then annealed. Finally, a P-electrode 1 is fabricated on the conductive layer 13, and an N-electrode 9 is fabricated on the N-GaN layer 8. The material is then split into strips, a cavity film is deposited, and a GaN-based laser diode is formed, as shown. Figure 3 As shown.

[0054] The GaN-based laser diode and its fabrication method proposed in this invention set the P-GaN layer 2 as a ridge structure and open holes 12 on the side of the ridge structure, and fill them with a low-refractive-index conductive layer 13 to cover the ridge structure and holes 12 at all angles. This not only forms a good ohmic contact, but also a higher light confinement effect to meet higher application requirements.

[0055] 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 GaN-based laser diode, characterized in that, The GaN-based laser diode includes a P-electrode, a P-GaN layer, a P-Cladding layer, a P-waveguide layer, a quantum well, an N-waveguide layer, an N-Cladding layer, an N-GaN layer, and an N-electrode. The P-GaN layer, P-Cladding layer, P-waveguide layer, quantum well, N-waveguide layer, N-Cladding layer, and N-GaN layer are arranged sequentially from top to bottom. The P-GaN layer is located in the middle of the P-Cladding layer and forms a ridge structure, and the width of the ridge structure is smaller than the width of the P-Cladding layer. An insulating layer is disposed on the P-Cladding layer in the area surrounding the ridge structure. The contact surface between the ridge structure and the insulating layer has an upward-facing hole. A conductive layer covers the outer surface of the ridge structure and the inner wall of the hole at all angles. The P-electrode is disposed on the conductive layer, and the N-electrode is disposed on the N-GaN layer. The conductive layer is an ITO conductive layer, and the bottom of the hole extends into the P-Cladding layer.

2. The GaN-based laser diode according to claim 1, characterized in that, The ridge structure has a width of 0.5 μm to 5 μm and a height of 200 nm to 800 nm.

3. The GaN-based laser diode according to claim 1, characterized in that, The insulating layer is a SiO2 insulating layer or a SiN insulating layer.

4. The method for fabricating a GaN-based laser diode as described in claim 1, characterized in that, The method includes: A corrosion-resistant metal was used as a mask to fabricate the P-GaN layer into a ridge-like structure. An insulating layer is grown on the ridge structure, the mask, and the P-Cladding layer; The contact area between the sidewall of the ridge structure and the insulating layer is etched to form a hole, the bottom of which extends into the P-Cladding layer. Etch the mask; A conductive layer is deposited on the ridge structure and the holes, and the conductive layer covers the outer surface of the ridge structure and the inner wall of the holes at all angles. The conductive layer is an ITO conductive layer. A P-electrode is fabricated on the conductive layer, and an N-electrode is fabricated on the N-GaN layer to form a GaN-based laser diode.

5. The manufacturing method according to claim 4, characterized in that, The ridge structure has a width of 0.5 μm to 5 μm and a height of 200 nm to 800 nm.

6. The manufacturing method according to claim 4, characterized in that, The insulating layer is a SiO2 insulating layer or a SiN insulating layer.

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