A nitride microdisk laser with an electrically driven air slot structure and a method for preparing the same

Abstract

The present invention discloses a nitride microdisk laser with an electrically driven air slot structure and a preparation method thereof. The laser uses silicon-based gallium nitride as a carrier, and includes a silicon substrate layer, a buffer layer, a u-type gallium nitride layer, an n-type gallium nitride layer, a quantum well layer and a p-type gallium nitride layer arranged in sequence from bottom to top. The n-type gallium nitride layer is provided with an n-type electrode, and the p-type gallium nitride layer is provided with a p-type electrode; an air slot structure is provided at the periphery of the quantum well layer. An electrically driven driving mode is realized by the n-type electrode and the p-type electrode, which is convenient to control and easy to integrate with other microelectronic devices. The outer whispering gallery mode is realized by the setting of the air slot, which not only has the characteristics of narrow line width and low threshold, but also easily interacts with the surrounding environment, and is suitable for gas sensing, communication and other aspects.

Description

Technical Field

[0001] The invention relates to a nitride micro-disk laser with an electrically driven air slot structure and a preparation method thereof, belonging to the technical field of lasers. Background Art

[0002] Whispering gallery mode laser is a stable mode field distribution formed in a symmetrical structure cavity by total reflection of light at the interface of high refractive index medium. Due to the narrow laser line width and low threshold of this mode, it is widely used in research and applications such as optical sensing, optical force, and nonlinear optics. The traditional whispering gallery mode localizes light inside the optical cavity through total reflection, and the interaction between light and matter is mostly limited to the light and the medium of the microcavity itself. The laser is confined to the high refractive index medium microcavity. Although the quality of this mode laser is high, it is not sensitive to the surrounding environment and is not conducive to coupling with other devices. In addition, the traditional light-driven mode also has problems such as low efficiency and instability.

[0003] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgement or any form of suggestion that the information constitutes the prior art already known to ordinary technicians in this field. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a nitride microdisk laser with an electrically driven air slot structure and a preparation method thereof. The prepared nitride microdisk laser realizes an electrically driven driving mode by energizing the n-type electrode and the p-type electrode. The quantum well in the middle emits light, and a part of the energy oscillates back and forth on the cavity wall above to form a resonant cavity, generate laser light, and is easy to control and easy to integrate with other microelectronic devices. By setting the air slot, an external whispering gallery mode is realized, which not only has the characteristics of narrow line width and low threshold, but also easily interacts with the surrounding environment, and is suitable for gas sensing, communication and other aspects.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] On the one hand, the present invention discloses an electrically driven air slot structured nitride microdisk laser, wherein the laser uses silicon-based gallium nitride as a carrier, and comprises a silicon substrate layer, a buffer layer, a u-type gallium nitride layer, an n-type gallium nitride layer, a quantum well layer and a p-type gallium nitride layer arranged in sequence from bottom to top.

[0007] The n-type gallium nitride layer is provided with an n-type electrode, and the p-type gallium nitride layer is provided with a p-type electrode;

[0008] An air groove structure is provided at the periphery of the quantum well layer.

[0009] Furthermore, a step structure is etched around the n-type gallium nitride layer, and the n-type gallium nitride layer includes a lower step layer and an upper step layer;

[0010] The n-type electrode is a ring-shaped electrode, which is arranged at the upper edge of the lower step layer.

[0011] Furthermore, the cross sections of the silicon substrate layer, the buffer layer, the u-type gallium nitride layer, the lower step layer, the upper step layer, the quantum well layer, the p-type gallium nitride layer and the p-type electrode are all circular.

[0012] Furthermore, the radius of the p-type gallium nitride layer is equal to the radius of the upper step layer, and both are larger than the radius of the quantum well layer, thereby forming an air slot structure.

[0013] Furthermore, the radius of the p-type electrode is smaller than the radius of the p-type gallium nitride layer;

[0014] The radius of the upper step layer is smaller than the radius of the lower step layer;

[0015] The radii of the buffer layer, the U-type gallium nitride layer, and the lower step layer are equal and smaller than the radius of the silicon substrate layer.

[0016] On the other hand, the present invention discloses a method for preparing an electrically driven air slot structured nitride microdisk laser, comprising the following steps:

[0017] Obtaining a wafer, wherein the wafer comprises a silicon substrate layer, a buffer layer, a u-type gallium nitride layer, an n-type gallium nitride layer, a quantum well layer, and a p-type gallium nitride layer arranged from bottom to top;

[0018] Using ICP etching technology, the wafer is etched to the upper surface of the silicon substrate layer and the n-type gallium nitride layer, so that a step structure is formed around the n-type gallium nitride layer;

[0019] Spin-coating photoresist on the upper surface of the wafer, and then using optical lithography technology to define a p-type electrode region and an n-type electrode region on the spin-coated photoresist layer;

[0020] Using electron beam evaporation technology to evaporate metal electrodes on the surface of the wafer, and removing residual photoresist according to the p-type electrode area and the n-type electrode area, thereby obtaining a p-type electrode and an n-type electrode;

[0021] The photochemical etching technology is adopted to laterally etch the quantum well layer to obtain an air groove structure.

[0022] Furthermore, the ICP etching technology is used to etch the wafer until the upper surface of the silicon substrate layer and the n-type gallium nitride layer, respectively, and the specific steps are as follows:

[0023] Spin-coating a photoresist on the upper surface of the wafer, and then defining a first area on the spin-coated photoresist layer using an optical photolithography technique;

[0024] Using ICP etching technology, etching downwards from the first region to the upper surface of the silicon substrate layer;

[0025] Re-spinning photoresist on the upper surface of the wafer, and then defining a second area on the spin-coated photoresist layer using optical lithography technology;

[0026] The ICP etching technology is used to etch downwards from the second region to the n-type gallium nitride layer, so that a step structure is formed around the n-type gallium nitride layer.

[0027] Furthermore, the material of the metal electrode includes nickel alloy.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The nitride microdisk laser of the electrically driven air slot structure of the present invention, on the one hand, realizes the electrically driven driving mode by energizing the n-type electrode and the p-type electrode, which is convenient for control and easy to integrate with other microelectronic devices; at the same time, compared with the traditional optical drive, the output efficiency is high and the output is stable, which is more suitable for industrialization and has better application prospects and application value. On the other hand, through the setting of the air slot, the energy of the light-emitting part of the quantum well oscillates back and forth on the upper cavity wall to form a resonant cavity, realizing the external echo gallery mode, which not only has the characteristics of narrow line width and low threshold, but also easily interacts with the surrounding environment, and is suitable for gas sensing, communication and other aspects.

[0030] The laser designed in the present invention can output light fields with different transverse electric wave modes and can be used to realize functional devices such as frequency modulation.

[0031] So far, most of the existing slot lasers are passive cavity structures, and there are almost no such slot lasers in the ultraviolet band. The electrically driven air slot structure nitride microdisk laser of the present invention can generate laser light around 373 nanometers, filling this gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a cross-sectional structural diagram of a nitride microdisk laser with an electrically driven air slot structure;

[0033] Figure 2 It is a top view of a nitride microdisk laser with an electrically driven air slot structure;

[0034] Figure 3 The present invention is a flow chart of a method for preparing a nitride microdisk laser with an electrically driven air slot structure;

[0035] In the figure: 1. Silicon substrate layer; 2. Buffer layer; 3. U-type gallium nitride layer; 4. n-type gallium nitride layer; 5. Quantum well layer; 6. p-type gallium nitride layer; 7. p-type electrode; 8. n-type electrode. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0037] Example 1

[0038] This embodiment 1 provides a method for preparing an electrically driven air slot structured nitride micro-disk laser, which specifically comprises the following steps:

[0039] Step 1: If Figure 3 As shown in Figures ac, the purchased commercial silicon-based gallium nitride wafer is first ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, and then blown dry with nitrogen.

[0040] Then, a photoresist AZ-5214 was spin-coated on the front side of the wafer, i.e., the upper surface of the p-type gallium nitride layer, at a speed of 4000 rpm using a coating machine. The spin coating time was 40 seconds and the thickness of the photoresist was 1.5 microns.

[0041] Afterwards, optical lithography technology is used to define a first area on the spin-coated photoresist layer. The first area is a circular area with a radius of 20 microns, and the model of the lithography machine is MA6.

[0042] Step 2: If Figure 3 As shown in FIG. 5 , electron beam evaporation technology is used to evaporate metal nickel with a thickness of 6 microns on the surface of the wafer, and then the residual photoresist is removed.

[0043] Step 3: If Figure 3 As shown in fg, the ICP etching technology is used to etch downwards to the upper surface of the silicon substrate layer, thereby transferring the first area defined in step 1 to the silicon substrate layer of the silicon-based gallium nitride wafer.

[0044] The wafer was then placed in a dilute nitric acid solution to remove residual metallic nickel, and then ultrasonically cleaned in acetone, anhydrous ethanol and deionized water in sequence, and then dried with nitrogen.

[0045] Step 4: If Figure 3 As shown in FIG. 1 , a photoresist AZ-5214 is spin-coated on the front side of the wafer, i.e., the upper surface of the p-type gallium nitride layer and the silicon substrate layer, at a speed of 4000 rpm using a coating machine. The spin coating time is 40 seconds and the photoresist thickness is 1.5 μm.

[0046] Then, optical lithography technology is used to define a second area on the spin-coated photoresist layer. The second area is a circle with a radius of 15 microns, and the lithography machine model is MA6.

[0047] Step 5: If Figure 3 As shown in FIG. 1 , electron beam evaporation technology is used to evaporate 6 microns of metal nickel on the surface of the wafer, and then the residual photoresist is removed.

[0048] Step 6: If Figure 3 As shown in FIG1 , the ICP etching technology is used to etch the nitride layer downward until it reaches the n-type gallium nitride layer, so that a step structure is formed around the n-type gallium nitride layer, thereby transferring the second region pattern defined in step 4 to the n-type gallium nitride layer.

[0049] The wafer was then placed in a dilute nitric acid solution to remove residual metallic nickel, and then ultrasonically cleaned in acetone, anhydrous ethanol and deionized water in sequence, and then dried with nitrogen.

[0050] Step 7: If Figure 3 As shown in FIG. 1 , a photoresist AZ-5214 is spin-coated on the front side of the wafer, i.e., the upper surface of the p-type gallium nitride layer, the n-type gallium nitride layer and the silicon substrate layer, at a speed of 4000 rpm using a coating machine. The spin coating time is 40 seconds and the photoresist thickness is 1.5 μm.

[0051] Optical lithography technology is used to define the electrode area on the spin-coated photoresist layer, where the electrode area includes a p-type electrode area and an n-type electrode area. The p-type electrode area is located on the p-type gallium nitride layer, and the n-type electrode area is located on the n-type gallium nitride layer. The p-type electrode area is a circular area with a radius of 13 microns, and the n-type electrode is a circular area with an inner radius of 16 microns and an outer radius of 19 microns. The lithography machine model is MA6.

[0052] Step 8: If Figure 3 As shown in pq, a metal electrode with a thickness of 10 nanometers is deposited on the surface of the wafer using electron beam evaporation technology, that is, a p-type electrode and an n-type electrode are respectively deposited on the p-type gallium nitride layer and the n-type gallium nitride layer, and then the residual photoresist is removed. The material of the metal electrode includes a nickel alloy.

[0053] Step 9: If Figure 3 As shown in r, photochemical etching technology is used. A xenon lamp is used to provide light source, and the area where the photoresist is spun is exposed through a photomask. The photoresist in the area exposed to ultraviolet light can be washed away with a developer. After drying, a dilute hydrochloric acid solution with a concentration of 0.004 mol / L is used as an etchant to corrode the quantum well layer to form an air groove structure of a certain depth. The etching is stopped when the depth is 5 microns.

[0054] It should be emphasized that the photochemical etching technology is used to etch the quantum well layer using a xenon lamp and dilute hydrochloric acid to make the air groove smoother and reduce the loss caused by roughness.

[0055] Example 2

[0056] This embodiment 2 provides an electrically driven air slot structured nitride microdisk laser prepared by the preparation method of embodiment 1, such as Figure 1 and Figure 2 As shown, the laser uses silicon-based gallium nitride as a carrier, and includes a silicon substrate layer 1, a buffer layer 2, a u-type gallium nitride layer 3, an n-type gallium nitride layer 4, a quantum well layer 5 and a p-type gallium nitride layer 6 arranged in sequence from bottom to top.

[0057] An n-type electrode 8 is provided on the n-type gallium nitride layer 4, and a p-type electrode 7 is provided on the p-type gallium nitride layer 6;

[0058] An air groove structure is provided around the quantum well layer 5 .

[0059] Specifically, a step structure is etched around the n-type gallium nitride layer 4 , and the n-type gallium nitride layer 4 includes a lower step layer and an upper step layer; the n-type electrode 8 is a ring electrode, and is disposed at the upper edge of the lower step layer.

[0060] The cross sections of the silicon substrate layer 1 , the buffer layer 2 , the u-type gallium nitride layer 3 , the lower step layer, the upper step layer, the quantum well layer 5 , the p-type gallium nitride layer 6 and the p-type electrode 7 are all circular.

[0061] The radius of the p-type electrode 7 is smaller than the radius of the p-type gallium nitride layer 6 .

[0062] The radius of the p-type gallium nitride layer 6 is equal to the radius of the upper step layer, and both are larger than the radius of the quantum well layer 5 , thereby forming an air slot structure and further forming a ring waveguide.

[0063] The radius of the upper step layer is smaller than the radius of the lower step layer;

[0064] The radius of the buffer layer 2 , the U-type gallium nitride layer 3 , and the lower step layer are equal and smaller than the radius of the silicon substrate layer 1 .

[0065] In this embodiment 2, the radius of the p-type electrode 7 is 13 microns, the radius of the p-type gallium nitride layer 6 and the radius of the upper step layer are both 15 microns, the radius of the quantum well layer 5 is 10 microns, the buffer layer 2, the u-type gallium nitride layer 3, and the lower step layer are all 19 microns, the radius of the silicon substrate layer 1 is 20 microns, and the n-type electrode 8 is a ring electrode with an inner radius of 16 microns and an outer radius of 19 microns.

[0066] The p-type electrode 7 is used as the positive electrode and the n-type electrode is used as the negative electrode, realizing the electric driving mode. The p-type region has a large hole concentration and diffuses to the n-type region, losing holes and becoming negatively charged. The n-type region electrons diffuse to the p-type region and lose electrons and become positively charged, forming an electric field.

[0067] It should be emphasized that the micro laser of this embodiment can generate laser light at around 373 nanometers, thus filling the gap of traditional lasers in this field.

[0068] In order to solve the problem of insensitivity to environmental perception of traditional whispering gallery modes, the present invention adopts a whispering gallery mode that localizes the optical mode in an extracavity structure. The optical mode is localized outside the microcavity through the method of surface plasmon resonance. Due to the large discontinuity between the two media, the light is confined in a low-refractive-index structure to form an extracavity whispering gallery mode laser. This mode laser is more sensitive to the surrounding environment and has more practical application value.

[0069] In view of the problems of low efficiency and instability of the traditional optical driving mode, the present invention adopts an electrically driven extracavity whispering gallery mode laser, which has greater practical application value.

[0070] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0071] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0072] The above is only 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 technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A nitride microdisk laser with an electrically driven air slot structure, characterized in that: The laser uses silicon-based gallium nitride as a carrier, and comprises a silicon substrate layer (1), a buffer layer (2), a u-type gallium nitride layer (3), an n-type gallium nitride layer (4), a quantum well layer (5) and a p-type gallium nitride layer (6) arranged in sequence from bottom to top. The n-type gallium nitride layer (4) is provided with an n-type electrode (8), and the p-type gallium nitride layer (6) is provided with a p-type electrode (7); An air slot structure is provided on the periphery of the quantum well layer (5); The n-type gallium nitride layer (4) comprises a lower step layer and an upper step layer; the radius of the p-type gallium nitride layer (6) is equal to the radius of the upper step layer and is greater than the radius of the quantum well layer (5), thereby forming an air slot structure.

2. The electrically driven air slot structured nitride micro laser according to claim 1, characterized in that: The periphery of the n-type gallium nitride layer (4) is etched with a step structure. The n-type electrode (8) is a ring-shaped electrode, and is arranged at the upper edge of the lower step layer.

3. The electrically driven air slot structured nitride microdisk laser according to claim 2, characterized in that: The cross sections of the silicon substrate layer (1), the buffer layer (2), the u-type gallium nitride layer (3), the lower step layer, the upper step layer, the quantum well layer (5), the p-type gallium nitride layer (6) and the p-type electrode (7) are all circular.

4. The electrically driven air slot structured nitride microdisk laser according to claim 3, characterized in that: The radius of the p-type electrode (7) is smaller than the radius of the p-type gallium nitride layer (6); The radius of the upper step layer is smaller than the radius of the lower step layer; The radii of the buffer layer (2), the U-type gallium nitride layer (3), and the lower step layer are equal and are all smaller than the radius of the silicon substrate layer (1).

5. A method for preparing an electrically driven air slot structured nitride microdisk laser, characterized in that: The steps include: Obtaining a wafer, wherein the wafer comprises, arranged from bottom to top, a silicon substrate layer (1), a buffer layer (2), a u-type gallium nitride layer (3), an n-type gallium nitride layer (4), a quantum well layer (5), and a p-type gallium nitride layer (6); Using ICP etching technology, the wafer is etched until the upper surface of the silicon substrate layer (1) and the n-type gallium nitride layer (4), so that a step structure is formed around the n-type gallium nitride layer (4); Spin-coating photoresist on the upper surface of the wafer, and then using optical lithography technology to define a p-type electrode region and an n-type electrode region on the spin-coated photoresist layer; Using electron beam evaporation technology to evaporate metal electrodes on the surface of the wafer, and removing residual photoresist according to the p-type electrode area and the n-type electrode area, thereby obtaining a p-type electrode (7) and an n-type electrode (8); The quantum well layer (5) is laterally etched using a photochemical etching technique to obtain an air groove structure.

6. The method for preparing a nitride microdisk laser with an electrically driven air slot structure according to claim 5, characterized in that: The ICP etching technology is used to etch the wafer until the upper surface of the silicon substrate layer (1) and the n-type gallium nitride layer (4), respectively. The specific steps are as follows: Spin-coating a photoresist on the upper surface of the wafer, and then defining a first area on the spin-coated photoresist layer using an optical photolithography technique; Using ICP etching technology, etching downward from the first region to the upper surface of the silicon substrate layer (1); Re-spinning photoresist on the upper surface of the wafer, and then defining a second area on the spin-coated photoresist layer using optical lithography technology; The ICP etching technology is used to etch downwards from the second region to the n-type gallium nitride layer (4), so that a step structure is formed around the n-type gallium nitride layer (4).

7. The method for preparing a nitride microdisk laser with an electrically driven air slot structure according to claim 5, characterized in that: The material of the metal electrode includes nickel alloy.

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