阅读说明：本技术 基于氮化镓-氮化铝核壳结构的微米线紫外光探测器件及其制备方法 (Micrometer-line ultraviolet light detection device based on gallium nitride-aluminum nitride core-shell structure and preparation method thereof ) 是由 李述体 施江 高芳亮 刘青 于 2020-04-29 设计创作，主要内容包括：本发明公开了一种基于氮化镓-氮化铝核壳结构的微米线紫外光探测器件及其制备方法,该器件包括镀有二氧化硅的硅片基底；硅片基底上设置有微米线层,微米线层由若干氮化镓-氮化铝核壳结构微米线形成,微米线层上镀有银电极。本发明所提供的基于氮化镓-氮化铝核壳结构的微米线紫外光探测器件其光开关比达到1.88×10<Sup>5</Sup>,响应度达4160A/W以及探测率达3.93×10<Sup>12</Sup>Jones。(The invention discloses a micron-line ultraviolet light detection device based on a gallium nitride-aluminum nitride core-shell structure and a preparation method thereof, the device comprises a silicon chip substrate plated with silicon dioxide, a micron-line layer is arranged on the silicon chip substrate and formed by a plurality of micron lines of the gallium nitride-aluminum nitride core-shell structure, and silver electrodes are plated on the micron-line layer 5 The responsivity reaches 4160A/W and the detectivity reaches 3.93 × 10 12 Jones。)

1. The micrometer-line ultraviolet light detection device based on the gallium nitride-aluminum nitride core-shell structure is characterized by comprising a silicon chip substrate plated with silicon dioxide; the silicon chip substrate is provided with a micrometer wire layer, the micrometer wire layer is formed by a plurality of gallium nitride-aluminum nitride core-shell structure micrometer wires, and the micrometer wire layer is plated with silver electrodes.

2. The micrometer-scale ultraviolet detector based on gallium nitride-aluminum nitride core-shell structure according to claim 1, wherein the micrometer-scale wire of gallium nitride-aluminum nitride core-shell structure is trapezoidal in shape, and the micrometer-scale wire of gallium nitride-aluminum nitride core-shell structure takes gallium nitride as core and aluminum nitride as shell; the thickness of the gallium nitride-aluminum nitride core-shell structure micrometer line is 3-3.3 micrometers, and the thickness of the aluminum nitride shell is 5-30 nm; the thickness of the silicon dioxide layer on the silicon wafer substrate is 190-210 nm; the thickness of the silver electrode is 250-350 nm.

3. The preparation method of the micrometer-line ultraviolet light detection device based on the gallium nitride-aluminum nitride core-shell structure according to claim 1 or 2, characterized by comprising the following steps:

and (3) photoetching: photoetching a pattern on a silicon substrate plated with silicon dioxide as a mask;

etching: etching according to the photoetching pattern to form a growing groove on the silicon substrate;

the growth step of the micron line: growing a gallium nitride-aluminum nitride core-shell structure micron line on the growth groove;

stripping the microwire: stripping the gallium nitride-aluminum nitride core-shell structure microwire;

and (3) a micron line transferring step: transferring the gallium nitride-aluminum nitride core-shell structure microwire to a silicon chip substrate plated with silicon dioxide to form a microwire layer;

silver plating an electrode: and plating silver electrodes on the micron line layer to obtain the micro-wire layer.

4. The method for preparing a micrometer-scale ultraviolet detector based on a gallium nitride-aluminum nitride core-shell structure according to claim 3, wherein in the photolithography step, the resistivity of the silicon substrate is greater than 3000 Ω -cm, and the crystal orientation of the silicon substrate is <100 >; the thickness of the silicon substrate is 515-535 microns, and the thickness of silicon dioxide on the silicon substrate is 190-210 nm.

5. The method for preparing a microwire ultraviolet detector based on a gallium nitride-aluminum nitride core-shell structure according to claim 3, wherein in the etching step, the photo-etched pattern is a stripe groove, and the growth groove is obtained by wet etching with potassium hydroxide; the growing grooves are inverted trapezoidal grooves; the length of the upper bottom of the inverted trapezoidal groove is 10-10.3 mu m, the length of the lower bottom is 4.2-4.5 mu m, the groove depth is 4.5-5 mu m, and the groove interval is 9.7-10 mu m; the crystal direction of the side wall of the inverted trapezoidal groove is <111>, and the crystal direction of the bottom surface of the inverted trapezoidal groove is <100 >.

6. The method for preparing a microwire ultraviolet detector based on gan-aln core-shell structure according to claim 5, wherein in the microwire growth step, gan-aln core-shell structure microwire is grown on the sidewalls of the inverted trapezoidal groove using a metal organic compound vapor deposition system.

7. The method for preparing a microwire ultraviolet detector based on a gallium nitride-aluminum nitride core-shell structure according to claim 3, wherein in the microwire stripping step, the gallium nitride-aluminum nitride core-shell structure microwire is stripped by using a mixed acid solution; the mixed acid solution is an aqueous solution of nitric acid and hydrofluoric acid.

8. The method for preparing a microwire ultraviolet detector based on gan-ain core-shell structure according to claim 3, wherein in the microwire transferring step, the peeled gan-ain core-shell structure microwire is suspended in a transferring agent and then transferred to the silicon wafer substrate plated with silicon dioxide; the transfer agent is water or alcohol solution.

9. The method for preparing a microwire ultraviolet detector based on gan-ain core-shell structure according to claim 3, wherein in the microwire transferring step, the gan-ain core-shell structure microwire is transferred to a silicon wafer substrate plated with silicon dioxide, and then is dried and heat treated, the heat treatment temperature is 60-80 ℃, and the heat treatment time is 1-10 minutes.

10. The method for preparing the microwire ultraviolet detector based on the gallium nitride-aluminum nitride core-shell structure according to claim 3, wherein in the step of plating silver on the electrode, the operation of plating silver on the electrode is performed by a metal plating machine under a steel wire mesh mask, and the wire diameter of the steel wire mesh mask is 10-25 μm.

Technical Field

The invention relates to the technical field of micro-nano gallium nitride material ultraviolet light detectors, in particular to a micro-nano line ultraviolet light detector based on a gallium nitride-aluminum nitride core-shell structure and a preparation method thereof.

Background

In recent years, as materials science research has extended from high to low dimensions, materials are becoming increasingly popular due to one-dimensional materials such as: microwires, microbands, microcolumns, etc. exhibit a large surface-to-volume ratio, a high crystal quality, and many optical and electrical characteristics different from bulk materials, thereby attracting much research interest.

Gallium nitride materials are an ideal short wavelength light emitting device material, and the band gap of gallium nitride and its alloys covers the spectral range from infrared to ultraviolet. Gallium nitride materials have suitable forbidden band widths (3.4eV) and are chemically stable, so that gallium nitride materials are ideal materials for manufacturing ultraviolet light detectors.

Gallium nitride ultraviolet light detectors tend to suffer from a large dark current, which limits the application of the detectors to some extent. In addition, the one-dimensional structure has a large volume surface area ratio, so that the one-dimensional structure is extremely sensitive to a surface state, and the response speed of the device is reduced. Therefore, how to reduce the dark current and alleviate the influence of the surface state becomes a problem to be solved at present, and the application of the core-shell structure at present is expected to solve the two problems. Aluminum nitride has a larger forbidden bandwidth, better physical and chemical stability and a crystal structure the same as gallium nitride, and a smaller lattice mismatch degree, so that the aluminum nitride becomes an ideal material for forming a core-shell structure. The core-shell structure of gallium nitride/aluminum nitride is expected to further improve the performance of the gallium nitride-based ultraviolet photoelectric detector. However, there is no ultraviolet light detector with a core-shell structure of gallium nitride/aluminum nitride with better performance.

Disclosure of Invention

In order to overcome the defects of the prior art, one of the purposes of the invention is to provide a micrometer-line ultraviolet light detection device based on a gallium nitride-aluminum nitride core-shell structure, which has a high optical on-off ratio.

The invention also aims to provide a preparation method of the micrometer-line ultraviolet light detection device based on the gallium nitride-aluminum nitride core-shell structure, which is easy to control the process and high in yield.

One of the purposes of the invention is realized by adopting the following technical scheme:

the micrometer-line ultraviolet light detection device based on the gallium nitride-aluminum nitride core-shell structure comprises a silicon wafer substrate plated with silicon dioxide; the silicon chip substrate is provided with a micrometer wire layer, the micrometer wire layer is formed by a plurality of gallium nitride-aluminum nitride core-shell structure micrometer wires, and the micrometer wire layer is plated with silver electrodes.

Furthermore, the shape of the gallium nitride-aluminum nitride core-shell structure microwire is trapezoidal, and the gallium nitride-aluminum nitride core-shell structure microwire takes gallium nitride as a core and aluminum nitride as a shell; the thickness of the gallium nitride-aluminum nitride core-shell structure micrometer line is 3-3.3 micrometers, and the thickness of the aluminum nitride shell is 5-30 nm; the thickness of the silicon dioxide layer on the silicon wafer substrate is 190-210 nm; the thickness of the silver electrode is 250-350 nm.

The second purpose of the invention is realized by adopting the following technical scheme:

a preparation method of a micrometer-line ultraviolet light detection device based on a gallium nitride-aluminum nitride core-shell structure comprises the following steps:

and (3) photoetching: photoetching a pattern on a silicon substrate plated with silicon dioxide as a mask;

etching: etching according to the photoetching pattern to form a growing groove on the silicon substrate;

the growth step of the micron line: growing a gallium nitride-aluminum nitride core-shell structure micron line on the growth groove;

stripping the microwire: stripping the gallium nitride-aluminum nitride core-shell structure microwire;

and (3) a micron line transferring step: transferring the gallium nitride-aluminum nitride core-shell structure microwire to a silicon chip substrate plated with silicon dioxide to form a microwire layer;

silver plating an electrode: and plating silver electrodes on the micron line layer to obtain the micro-wire layer.

Further, in the photolithography step, the resistivity of the silicon substrate is greater than 3000 Ω · cm, and the crystal orientation of the silicon substrate is <100 >; the thickness of the silicon substrate is 515-535 microns, and the thickness of silicon dioxide on the silicon substrate is 190-210 nm.

Further, in the etching step, the photoetching pattern is a stripe groove, and the growing groove is obtained by utilizing a potassium hydroxide wet etching method; the growing grooves are inverted trapezoidal grooves; the length of the upper bottom of the inverted trapezoidal groove is 10-10.3 mu m, the length of the lower bottom is 4.2-4.5 mu m, the groove depth is 4.5-5 mu m, and the groove interval is 9.7-10 mu m; the crystal direction of the side wall of the inverted trapezoidal groove is <111>, and the crystal direction of the bottom surface of the inverted trapezoidal groove is <100 >.

Further, in the micron line growing step, a metal organic compound vapor deposition system is adopted to grow the micron line with the gallium nitride-aluminum nitride core-shell structure on the side wall of the inverted trapezoidal groove.

Further, in the microwire stripping step, stripping the gallium nitride-aluminum nitride core-shell structure microwire by using a mixed acid solution; the mixed acid solution is an aqueous solution of nitric acid and hydrofluoric acid.

Further, in the step of transferring the microwire, firstly suspending the peeled gallium nitride-aluminum nitride core-shell structure microwire in a transfer agent, and then transferring the microwire to a silicon wafer substrate plated with silicon dioxide; the transfer agent is water or alcohol solution.

Further, in the microwire transferring step, the gallium nitride-aluminum nitride core-shell structure microwire is transferred to a silicon wafer substrate plated with silicon dioxide, and then is dried and heat-treated, wherein the heat-treating temperature is 60-80 ℃, and the heat-treating time is 1-10 minutes.

Further, in the step of plating silver on the electrode, a metal coating machine is used for plating silver on the electrode under the steel wire mesh mask, and the wire diameter of the steel wire mesh mask is 10-25 mu m.

Compared with the prior art, the invention has the beneficial effects that:

according to the micrometer-line ultraviolet light detection device based on the gallium nitride-aluminum nitride core-shell structure, the gallium nitride-aluminum nitride in the micrometer line forms the core-shell structure and then belongs to the I-type core-shell structure, namely the whole forbidden band of the gallium nitride is covered by the forbidden band of the aluminum nitride, and the structure can effectively restrict electron-hole pairs, reduce electric leakage, reduce non-radiative recombination and improve the stability of the device. The GaN has high surface state, and the wide bandgap semiconductor material deposited on the surface of the GaN to form an I-type core-shell structure can effectively passivate the surface and weaken the surface state bandIn addition, the aluminum nitride not only increases the Schottky contact barrier height between the gallium nitride microwire and the silver electrode, enhances the built-in electric field and prolongs the service life of photon-generated carriers, thereby greatly reducing dark current and further improving the optical on-off ratio of the micron-level gallium nitride ultraviolet detector, and experimental results show that the optical on-off ratio of the gallium nitride/aluminum nitride core-shell structure microwire ultraviolet detector obtained by the invention reaches 1.88 × 10⁵The responsivity reaches 4160A/W and the detectivity reaches 3.93 × 10¹²Jones。

Drawings

FIG. 1 is a scanning electron mirror image of the cross section of a micron line of a non-peeled GaN-AlN core-shell structure grown on a patterned silicon substrate in accordance with example 1 of the present invention;

fig. 2 is a micrometer scanning electron mirror image of a single gan-aln core-shell structure actually stripped in example 1 of the present invention, where the left inset is a partially enlarged micrometer view, and the right inset is an enlarged micrometer end view;

fig. 3 is a model diagram of optoelectronic property measurement of a gallium nitride-aluminum nitride core-shell structure microwire ultraviolet light detector obtained in example 1 of the present invention;

FIG. 4 is a photoluminescence spectrum of a micron line of a GaN-AlN core-shell structure in example 1 of the present invention;

fig. 5 is a current-voltage characteristic curve diagram of a gallium nitride-aluminum nitride core-shell structure microwire ultraviolet light detector obtained in embodiment 1 of the present invention;

fig. 6 is a current-voltage characteristic curve diagram of a gallium nitride-aluminum nitride core-shell structure microwire ultraviolet light detector in embodiment 1 of the present invention;

fig. 7 is a time response diagram of a gallium nitride-aluminum nitride core-shell structure microwire ultraviolet light detector in embodiment 1 of the present invention;

fig. 8 is an enlarged view of the rising process and the falling process of the time response of the gallium nitride-aluminum nitride core-shell structure microwire ultraviolet light detector in embodiment 1 of the present invention.

In the figure: 10. a silicon wafer substrate; 20. a GaN core; 21. an AlN shell; 30. and a silver electrode.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and the detailed description, and it should be noted that any combination of the embodiments or technical features described below can be used to form a new embodiment without conflict.

A micrometer-line ultraviolet light detection device based on a gallium nitride-aluminum nitride core-shell structure comprises a silicon wafer substrate plated with silicon dioxide; the silicon chip substrate is provided with a micrometer wire layer which is formed by a plurality of gallium nitride-aluminum nitride core-shell structure micrometer wires, and the micrometer wire layer is plated with silver electrodes.

As a further embodiment, the shape of the gallium nitride-aluminum nitride core-shell structure microwire is trapezoidal, and the gallium nitride-aluminum nitride core-shell structure microwire takes gallium nitride as a core and aluminum nitride as a shell; the thickness of the gallium nitride-aluminum nitride core-shell structure microwire is 3-3.3 μm, preferably 3-3.2 μm, and more preferably 3-3.1 μm; the thickness of the aluminum nitride shell is 5-30 nm; the thickness setting can well meet the application requirement, the crystal quality is good, and the crystal can be well matched with an etching process.

As a further implementation mode, the thickness of the silicon dioxide layer on the silicon wafer base is 190-210 nm, and the thinner thickness is beneficial to reducing the cost under the condition of ensuring the substrate insulation. The thickness of the silver electrode is 250-350 nm.

The micrometer-line ultraviolet light detector based on the gallium nitride-aluminum nitride core-shell structure provided by the invention is used in an ultraviolet light detector, can obviously reduce dark current, improve response speed, and improve the optical on-off ratio and responsivity of the existing micro-nanometer-level gallium nitride ultraviolet light detector, wherein the optical on-off ratio reaches 1.88 × 10⁵The responsivity reaches 4160A/W and the detectivity reaches 3.93 × 10¹²Jones。

A preparation method of a micrometer-line ultraviolet light detection device based on a gallium nitride-aluminum nitride core-shell structure comprises the following steps:

and (3) photoetching: photoetching a pattern on a silicon substrate plated with silicon dioxide as a mask;

etching: etching according to the photoetching pattern to form a growing groove on the silicon substrate;

the growth step of the micron line: growing a gallium nitride-aluminum nitride core-shell structure micron line on the growth groove;

stripping the microwire: stripping the gallium nitride-aluminum nitride core-shell structure microwire;

and (3) a micron line transferring step: transferring the gallium nitride-aluminum nitride core-shell structure microwire to a silicon chip substrate plated with silicon dioxide to form a microwire layer;

silver plating an electrode: and plating silver electrodes on the micron line layer to obtain the micro-scale wire.

As a further embodiment, in the photolithography step, the resistivity of the silicon substrate is greater than 3000 Ω · cm, and the crystal orientation of the silicon substrate is <100 >; the thickness of the silicon substrate is 515-535 μm, and the thickness of the silicon dioxide on the silicon substrate is 190-210 nm. The specific embodiment is not particularly limited when the photolithography operation is performed.

As a further implementation mode, in the etching step, the photoetching pattern is a stripe groove, and a growing groove is obtained by utilizing potassium hydroxide wet etching; the growth grooves are inverted trapezoidal grooves; in order to control the growth of the obtained micron line to be trapezoidal and the thickness to be 3-3.3 microns, the length of the upper bottom of an inverted trapezoidal groove is 10-10.3 microns, the length of the lower bottom is 4.2-4.5 microns, the depth of the groove is 4.5-5 microns, and the distance between the grooves is 9.7-10 microns (the distance between the grooves is calculated by two adjacent sides of two adjacent parallel grooves after etching); the crystal orientation of the side wall of the inverted trapezoidal groove is <111>, and the crystal orientation of the bottom surface is <100 >.

As a further implementation manner, in the etching step, the silicon substrate plated with silicon dioxide as a mask is fully covered with a photoetching pattern to form a photoetching pattern array (stripe groove array), and growth grooves obtained by utilizing potassium hydroxide wet etching are parallel inverted trapezoid groove arrays. The bottom surface of the inverted trapezoid groove array is parallel to the silicon substrate silicon dioxide mask layer, the side wall and the bottom surface form a certain angle and are parallel to each other, namely, a fixed angle, preferably 54.74 degrees, is formed between the side wall and the bottom surface, and the side wall are parallel to each other in spatial position; the inverted trapezoidal groove array is parallel to the crystal direction of the silicon substrate, namely the silicon substrate is cut with a reference edge along a crystal plane, and the trapezoidal groove array is parallel to the reference edge. The invention has no special requirement on the number of the grooves of the inverted trapezoidal groove array, and can be distributed on the whole substrate in principle.

As a further embodiment, in the microwire growth step, a gallium nitride-aluminum nitride core-shell structure microwire is grown on the sidewalls of the inverted trapezoidal groove using a metal organic compound vapor deposition system. Firstly growing an aluminum nitride buffer layer on the pattern substrate, and then growing a gallium nitride-aluminum nitride core-shell structure micrometer wire on the side wall of the inverted trapezoidal groove, wherein the aluminum nitride shell completely wraps the gallium nitride core.

As a further embodiment, in the microwire stripping step, stripping the gallium nitride-aluminum nitride core-shell structure microwire by using a mixed acid solution; the mixed acid solution is an aqueous solution of nitric acid and hydrofluoric acid, the mixed acid solution can carry out isotropic corrosion on the silicon substrate, the stripping surface of the obtained micron line is smooth and clean, and the stripping rate can be well controlled according to the ratio of the preparation; the volume ratio of the nitric acid to the hydrofluoric acid to the water is preferably (4-6): 1-3): 1, and more preferably 5:1: 1.

As a further embodiment, in the microwire transferring step, residual nitric acid and hydrofluoric acid are present in the stripped microwire, which is dangerous; in addition, some etched small particles need to be cleaned, so that the subsequent device is convenient to manufacture. Therefore, the peeled gallium nitride-aluminum nitride core-shell structure microwire needs to be suspended in a transfer agent and then transferred to a silicon chip substrate plated with silicon dioxide; the transfer agent is water or alcohol solution. The alcohol solution is one or more of volatile alcohol solutions, and the alcohol solution is preferably one or two of isopropanol solution and ethanol solution. In the present invention, the concentration of the alcohol solution is preferably 99.7%.

As a further embodiment, in the microwire transferring step, the ratio of the area of the substrate of the gallium nitride-aluminum nitride core-shell structured microwire to the volume of the transfer agent is preferably 2.5cm²6m L, the transfer number of the GaN-aluminum nitride core-shell structure micron line is generally 60-80.

As a further embodiment, in the microwire transferring step, the microwire of the GaN-aluminum nitride core-shell structure transferred to the silicon wafer substrate coated with silicon dioxide is distributed in a single layer without crossing and stacking, and the step is performed by spin coating at a rotation speed of 500r/min for 30 s. According to the invention, after the gallium nitride-aluminum nitride core-shell structure micron line is transferred to the silicon wafer substrate plated with silicon dioxide, a heating table is preferably used for drying and heat treatment to remove a transfer agent introduced in the transfer process, and the heat treatment temperature is preferably 60-80 ℃, more preferably 62-78 ℃, and most preferably 65-75 ℃; the heat treatment time is preferably 1 to 10 minutes, more preferably 2 to 8 minutes, and most preferably 5 to 6 minutes. In an embodiment of the present invention, the silicon wafer substrate coated with silicon dioxide is preferably heat treated.

In the step of silver plating, a metal coating machine is used for silver plating electrode operation under a steel wire mesh mask, and the wire diameter of the steel wire mesh mask is 10-25 mu m.

The invention provides a micron-line ultraviolet light detector based on a gallium nitride-aluminum nitride core-shell structure, wherein gallium nitride-aluminum nitride in a micron line forms a core-shell structure and then belongs to an I-type core-shell structure, namely, the whole forbidden band of the gallium nitride is covered by the forbidden band of the aluminum nitride, the structure can effectively restrict electron-hole pairs, reduce electric leakage, reduce non-radiative recombination and improve the stability of the device, the GaN has a higher surface state, a wide forbidden band semiconductor material is deposited on the surface to form the I-type core-shell structure, the surface can be effectively passivated, and the influence brought by the surface state is weakened⁵The responsivity reaches 4160A/W and the detectivity reaches 3.93 × 10¹²Jones。

The following are specific examples of the present invention, and raw materials, equipments and the like used in the following examples can be obtained by purchasing them unless otherwise specified.