CN114336278A - A kind of vertical emission ZnO suspended bowl laser and preparation method thereof - Google Patents

Abstract

The invention discloses a vertical cavity surface laser transmitter with a ZnO suspended bowl-shaped structure and a preparation method thereof. The laser transmitter uses a silicon-based SOI wafer as a carrier, and includes a silicon substrate layer and a silicon dioxide layer sequentially arranged from bottom to top. , silicon dioxide pillar layer, silicon dioxide disc layer, zinc oxide disc layer; the laser emitter is formed with a plurality of zinc oxide disc layers, silicon dioxide disc layers, dioxide Silicon pillar layer up to the hole of the silicon dioxide layer. The laser transmitter of the invention has extremely high optical gain and extremely low loss, which is beneficial to the integration of optoelectronic devices, and has the advantages of high quality, low threshold and low loss, and the preparation method has the advantages of good manufacturability and high processing precision.

Description

A kind of vertical emission ZnO suspended bowl laser and preparation method thereof

technical field

The invention belongs to the technical field of lasers, and in particular relates to a vertical cavity surface laser emitter with a suspended silicon disk structure and a preparation method thereof.

Background technique

The bowl laser can change the direction of laser emission to make it emit vertically, and prepare a more easily coupled vertical cavity surface laser emitter (VCSEL). ZnO vertical cavity surface laser emitter is a new type of semiconductor laser with vertical light-emitting structure, and its emission wavelength is in the near-ultraviolet band. VCSELs have the advantages of circular symmetrical light spot, high coupling efficiency with optical fibers, and the ability to fabricate high-density two-dimensional arrays. Therefore, VCSELs are considered to be ideal light sources for next-generation semiconductor illumination, micro-projection, and full-color display applications.

The wide direct band gap (3.4 eV) and strong exciton binding energy (60 meV) of ZnO make it an important candidate for short-wave optoelectronic functional materials and devices. Over the past decade, great attention has been paid to the ultraviolet optoelectronic properties of this semiconductor, especially the laser properties.

Therefore, how to use the zinc oxide material and the microcavity structure to achieve high-quality and low-loss laser will be the problem to be solved by the present invention.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a vertical cavity surface laser emitter with a ZnO suspended bowl structure and a preparation method thereof. The laser emitter has extremely high optical gain and extremely low loss, which is beneficial to optoelectronic devices. Integration has the advantages of high quality, low threshold and low loss, and its preparation method has the advantages of good manufacturability and high processing accuracy.

According to an aspect of the present specification, a vertical cavity surface laser transmitter with a ZnO suspended bowl structure is provided. The laser transmitter uses a silicon-based SOI wafer as a carrier, and includes a silicon substrate layer, a silicon dioxide layer and a silicon dioxide layer sequentially arranged from bottom to top. a silicon layer, a silicon dioxide pillar layer, a silicon dioxide disc layer, and a zinc oxide disc layer; the laser transmitter is formed with a plurality of etched through the zinc oxide disc layer, the silicon dioxide disc layer, The silica pillar layer reaches the hole of the silica layer; the silica disc layer and the zinc oxide disc layer form a bowl-shaped microcavity.

The above technical solution has a suspended silicon disk microcavity supported by a columnar shape with smooth edges, which can reduce the bending loss of the microcavity and the scattering loss caused by the rough side surface, so that the overall laser emitter has extremely low loss.

In the above technical solution, "suspended" makes the upper and lower surfaces of the zinc oxide film microcavity surrounded by low-refractive-index air, and the total internal reflection of light at the interface of the high-refractive-index semiconductor and the microcavity interface of the low-refractive-index air around it is in the form of WGM. Conduction, the optical mode in the vertical direction is also strongly confined, and this WGM conduction effect and optical confinement greatly reduces the optical loss caused by optical scattering and transmission, resulting in a sufficiently large optical gain to maintain the lasing effect.

In the above technical solution, the shape of the microcavity of the vertical cavity surface laser transmitter is bowl-shaped, and the bowl-shaped microcavity is equivalent to a concave mirror, which can vertically focus and emit the generated WGM laser.

Further, the silicon dioxide layer and the silicon dioxide disc layer are caused by annealing silicon at high temperature.

Further, the silica pillar layer is obtained by suspending the BOE.

Further, a zinc oxide disk layer is suspended on the silica disk layer.

Further, the zinc oxide disc layer on the silicon dioxide disc layer is covered by the crystal growth technology MBE.

According to an aspect of the present specification, there is provided a method for preparing a vertical cavity surface laser emitter with the ZnO suspended bowl structure, comprising the following steps:

Spin-coating photoresist on the surface of a silicon-based SOI wafer, and define a disc structure on the spin-coated photoresist layer;

Using the photoresist as a mask, the silicon layer is etched to the silicon dioxide pillar layer;

The etched wafer is suspended by BOE to obtain a silicon dioxide pillar layer;

High temperature quenching to obtain silicon dioxide layer and silicon dioxide disc layer;

On the silica disc layer, zinc oxide is suspended and coated to obtain a zinc oxide disc layer.

The above technical scheme utilizes optical lithography, RIE etching, and hydrofluoric acid and ammonia mixed solution etching process to prepare ZnO suspended bowl-shaped microcavity. The ZnO suspended bowl-shaped microcavity with smooth edges reduces the bending loss of the microcavity and the scattering loss caused by the rough side.

Further, the zinc oxide disc layer is covered on the silicon dioxide disc layer by molecular beam epitaxy.

Compared with the prior art, the beneficial effects of the present invention include:

The invention has a ZnO suspended bowl-shaped microcavity supported by a columnar shape with smooth edges, which can reduce the bending loss of the microcavity and the scattering loss caused by the rough side surface, so that the overall laser emitter has extremely low loss.

In the present invention, the upper and lower surfaces of the zinc oxide film microcavity are surrounded by air with low refractive index by "suspending", and the total internal reflection of light at the interface of the high refractive index semiconductor and the microcavity interface of the surrounding low refractive index air is conducted in the form of WGM, The optical modes in the vertical direction are also strongly confined, and this WGM conduction and optical confinement greatly reduces the optical losses caused by optical scattering and transmission, resulting in a sufficiently large optical gain to maintain lasing.

The present invention designs and optimizes the WGM laser from the perspectives of laser directional focused emission, mode selection and improvement of Q value through a unique bowl-shaped ZnO suspended microcavity to study the technical method and physical process of WGM ultraviolet laser performance improvement.

Description of drawings

1 is a side view of a vertical cavity surface laser emitter with a ZnO suspended bowl structure according to an embodiment of the present invention.

2 is a top view of a vertical cavity surface laser emitter with a ZnO suspended bowl structure according to an embodiment of the present invention.

3 is a process flow diagram of a vertical cavity surface laser emitter with a ZnO suspended bowl structure according to an embodiment of the present invention.

In the figure: silicon substrate layer 1, silicon dioxide layer 2, silicon dioxide pillar layer 3, silicon dioxide disc layer 4, and zinc oxide disc layer 5.

Detailed ways

The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

In the present invention, unless otherwise expressly specified and limited, a first feature "on" or "under" a second feature may include the first and second features in direct contact, or may include the first and second features Not directly but through additional features between them. Also, the first feature being "above", "over" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is level higher than the second feature. The first feature is "below", "below" and "below" the second feature includes the first feature being directly below and diagonally below the second feature, or simply means that the first feature has a lower level than the second feature.

The invention provides a vertical cavity surface laser emitter with a ZnO suspended bowl-shaped structure. The advanced micro-nano processing technology is used to design and prepare a ZnO suspended bowl-shaped microcavity, and the WGM ultraviolet laser is studied through a unique bowl-shaped zinc oxide suspended microcavity. Technical methods and physical processes for performance improvement, design and optimize WGM lasers from the perspectives of laser directional focused emission, mode selection, and improvement of Q value.

The laser uses a silicon-based SOI wafer as a carrier, and from bottom to top is a silicon substrate layer, a silicon dioxide layer, a silicon dioxide pillar layer, a silicon dioxide disc layer, and a zinc oxide disc layer.

The silicon dioxide disc layer and the zinc oxide disc layer form a bowl-shaped microcavity, and the bowl-shaped microcavity is equivalent to a concave mirror, which can make the generated WGM laser vertically focus and emit.

The silicon dioxide layer and the silicon dioxide disc layer result from the annealing of silicon at high temperature. The silica pillar layer is obtained by using BOE to suspend.

A zinc oxide disc layer is suspended on the silica disc layer. The zinc oxide disk layer is covered on the silicon dioxide disk layer. The process is simple and it is easy to obtain high-quality low-threshold laser light. The zinc oxide disk layer has a high refractive index and a smooth surface, which ensures the total internal reflection optical gain loop. The effective formation of , thereby greatly reducing the loss caused by optical scattering and transmission.

Further, the zinc oxide disc layer on the silicon dioxide disc layer is covered by the crystal growth technology MBE.

The present invention provides a method for preparing a vertical cavity surface laser transmitter with a suspended silicon disk structure, which is used to prepare a vertical cavity surface laser transmitter with a suspended silicon disk structure. The specific parameters of the materials of each layer are: the thickness of the silicon substrate layer 1 is 750um, the thickness of the silicon dioxide layer 2 is 2um, and the thickness of the top layer silicon disk is about 240nm.

The preparation process is as follows:

Step 1: The purchased silicon substrate SOI wafer is ultrasonically cleaned in sequence with acetone, anhydrous ethanol and deionized water, and then blown dry with nitrogen gas; spin-coating at 4000 rpm on the front of the wafer using a glue spinner Photoresist AZ-5214, spin coating time is 40s (resist thickness is 1.5 microns).

The second step: using optical lithography technology, define the pattern of the disc structure on the spin-coated photoresist layer, and the lithography machine model is MA6.

The third step: using the RIE etching technology and using the photoresist as a mask, the silicon layer is etched to the silicon dioxide pillar layer 3, and finally the remaining photoresist is removed.

The fourth step: put the wafer into the prepared mixed solution of ammonia water and hydrofluoric acid, and carry out BOE suspension for 30s to obtain a silicon dioxide pillar layer 3 .

The fifth step: quench the wafer at high temperature, so that the silicon layer with a thickness of 240nm is converted into a silicon dioxide layer to obtain a silicon dioxide layer 2 (after the bottom silicon layer material is quenched at a high temperature, a silicon layer with a thickness of 240nm on the surface is obtained. It is chemically transformed into silicon dioxide by heating to form silicon dioxide layer) and silicon dioxide disc layer 4 (similar to the formation principle of silicon dioxide layer 2, the uppermost thin silicon layer becomes silicon dioxide after high temperature disc layer 4).

The sixth step: using molecular beam epitaxy technology, the surface of the silicon dioxide disc layer is covered with zinc oxide to obtain the zinc oxide disc layer 5 .

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or some or all of the technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.

Claims (7)

1. a vertical cavity surface laser transmitter of ZnO suspension bowl structure, it is characterized in that, described laser transmitter takes silicon-based SOI wafer as carrier, comprises the silicon substrate layer (1) that is arranged successively from bottom to top, carbon dioxide a silicon layer (2), a silicon dioxide pillar layer (3), a silicon dioxide disc layer (4), and a zinc oxide disc layer (5); the laser emitter is formed with a plurality of oxides etched from top to bottom Zinc disk layer (5), silicon dioxide disk layer (4), silicon dioxide pillar layer (3) up to the holes of the silicon dioxide layer (2); the silicon dioxide disk layer (4) and the oxide The zinc disc layer (5) forms a bowl-shaped microcavity. 2. The vertical cavity surface laser emitter of the ZnO suspended bowl structure according to claim 1, wherein the silicon dioxide layer (2) and the silicon dioxide disc layer (4) are silicon in high temperature due to annealing. 3 . The vertical cavity surface laser emitter with ZnO suspended bowl structure according to claim 1 , wherein the silicon dioxide pillar layer ( 3 ) is obtained by using BOE to suspend. 4 . 4 . The vertical cavity surface laser emitter with a ZnO suspension bowl structure according to claim 1 , wherein a zinc oxide disc layer ( 5 ) is suspended on the silicon dioxide disc layer ( 4 ). 5 . 5. the vertical cavity surface laser emitter of ZnO suspension bowl structure according to claim 1, is characterized in that, the zinc oxide disc layer (5) on the described silicon dioxide disc layer (4), is to adopt Crystal growth techniques covered on MBE. 6. A preparation method of the vertical cavity surface laser emitter of the suspended silicon disk structure according to any one of claims 1-5, characterized in that, comprising the following steps: Spin-coating photoresist on the surface of a silicon-based SOI wafer, and define a disc structure on the spin-coated photoresist layer; Using the photoresist as a mask, the silicon layer is etched to the silicon dioxide pillar layer; The etched wafer is suspended by BOE to obtain a silicon dioxide pillar layer (3); High temperature quenching to obtain silicon dioxide layer (2) and silicon dioxide disc layer (4); On the silica disc layer (4), zinc oxide is suspended and coated to obtain a zinc oxide disc layer (5). 7. the preparation method of the vertical cavity surface laser emitter of the described ZnO suspension bowl structure according to claim 6, is characterized in that, adopts molecular beam epitaxy to cover zinc oxide disc layer (4) on silicon dioxide disc layer (4). 5).

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