CN112670358B

CN112670358B - Diamond-based ultraviolet detector and preparation method thereof

Info

Publication number: CN112670358B
Application number: CN202011535536.5A
Authority: CN
Inventors: 华斌; 辜艺敏; 顾星; 倪贤锋; 范谦
Original assignee: SOUTHEAST UNIVERSITY SUZHOU INSTITUTE
Current assignee: SOUTHEAST UNIVERSITY SUZHOU INSTITUTE
Priority date: 2020-12-23
Filing date: 2020-12-23
Publication date: 2021-08-03
Anticipated expiration: 2040-12-23
Also published as: CN112670358A

Abstract

The invention discloses a diamond-based ultraviolet detector, which comprises a diamond film, a first electrode, a second electrode and an insulating layer, wherein the diamond film is arranged on the first electrode; the diamond film comprises diamond micro-columns, a first groove, a second groove and a third groove, the diamond micro-columns are periodically distributed on the surface of the diamond film, a gap between the diamond micro-columns is the third groove, and the first groove and the second groove which are communicated with the third groove are respectively arranged on the two sides of the third groove; the first electrode is arranged on the first groove and the third groove; the second electrode is arranged above the second groove and the third groove; the insulating layer is between the stacked areas of the first electrode and the second electrode. The invention also discloses a preparation method of the diamond-based ultraviolet detector. According to the invention, the first electrode and the second electrode which are stacked are arranged by using the groove, so that the surface duty ratio of the diamond film is improved, the number of current carriers is increased, the effective collection of the current carriers is realized, and the sensitivity and the responsiveness are improved.

Description

Diamond-based ultraviolet detector and preparation method thereof

Technical Field

The invention relates to a detector and a manufacturing method thereof, in particular to a diamond-based ultraviolet detector and a manufacturing method thereof.

Background

In the research of wide-bandgap ultraviolet detectors, the research of diamond film ultraviolet detectors is one of the most attractive topics. The forbidden band width of the diamond is 5.5eV, the diamond corresponds to 225nm ultraviolet wavelength, and the diamond has solar blind characteristics, so that the device can be used under the background of visible light without configuring a filter or a dielectric coating. Diamond also has many excellent electrical, optical, thermal and mechanical properties as well as high radiation resistance and physicochemical stability, such as low dielectric constant, high breakdown voltage, high electron/hole mobility, high thermal conductivity, and the like. Due to the characteristics, the diamond has wide application in the detection technology, and particularly has prominent performance in the technical field of high-energy particle, X-ray and ultraviolet detection.

Currently, there are generally two types of diamond-based uv detectors: one is an ultraviolet detector for depositing a metal electrode with a planar interdigital structure on the upper surface of the diamond, and the other is a sandwich structure for depositing metal electrodes on the upper surface and the lower surface of the diamond. However, in the ultraviolet detector with the electrode of the planar interdigital structure, the positive and negative interdigital electrodes all need to meet the condition of certain width, so that the interdigital electrodes almost occupy the whole upper surface of the diamond, the irradiated area of the diamond is very small, and the generation quantity of current carriers is influenced; in addition, one electrode of the ultraviolet detector with the sandwich structure is arranged on the back, so that light blocking of the front electrode is reduced, but the whole thickness is thick, so that drifting and collection of current carriers are not facilitated, and the device performance of the detector is also influenced.

Disclosure of Invention

The purpose of the invention is as follows: in order to overcome the defects in the prior art, the invention aims to provide the diamond-based ultraviolet detector with high sensitivity and high responsivity, and the invention also aims to provide a simple and convenient preparation method of the diamond-based ultraviolet detector.

The technical scheme is as follows: the invention relates to a diamond-based ultraviolet detector which comprises a diamond film, a first electrode, a second electrode and an insulating layer, wherein the diamond film is arranged on the first electrode; the diamond film comprises diamond micro-columns, first grooves, second grooves and third grooves, the diamond micro-columns are periodically distributed on the surface of the diamond film, gaps between every two diamond micro-columns are the third grooves, the first grooves and the second grooves are respectively arranged on opposite sides of the diamond film, and the first grooves and the second grooves communicated with the third grooves are respectively arranged on two sides of the third grooves; the first electrode is arranged on the first groove and the third groove; the second electrode is arranged above the second groove and the third groove; the insulating layer is arranged between the stacked areas of the first electrode and the second electrode.

The upper surface of the second electrode is not higher than the upper surface of the diamond microcolumn. The first and second electrodes each include a shank and a tooth, the tooth of the first electrode being stacked with the tooth of the second electrode over the third groove.

The height of the diamond microcolumn is 5-20 μm, and the width is 40-60 μm. The width of the third groove is 10-30 μm. The thickness of the diamond film is less than or equal to 10 mu m. The thickness of the insulating layer is 2-4 μm.

The insulating layer is made of silicon dioxide, silicon nitride, aluminum oxide, aluminum nitride or titanium oxide material. The first electrode and the second electrode are made of gold, chromium or titanium materials.

The preparation method of the diamond-based ultraviolet detector comprises the following steps:

s1: preparing a diamond film;

s2: etching the diamond film to form a diamond microcolumn, a first groove, a second groove and a third groove on the surface of the diamond film;

s3: and sequentially depositing a first electrode, an insulating layer and a second electrode in the first groove, the second groove and the third groove, and removing redundant parts. The first electrode and the second electrode are partially stacked above the third groove, and the insulating layer is formed between the stacked areas of the first electrode and the second electrode.

Has the advantages that: compared with the prior art, the invention has the following remarkable characteristics: utilize the setting of first slot, second slot and third slot, first electrode and the second electrode of piling up, the area that the metal electrode accounts for diamond film surface has been reduced, the detection area that diamond film received the irradiation has greatly been increased, the duty cycle on diamond film surface has been improved, thereby increase the production quantity of current carrier, and make the electric field can extensively and evenly distributed in diamond microcolumn and diamond film, the effective collection of all current carriers in the diamond film has been realized, thereby the sensitivity and the responsivity of detector have been improved.

Drawings

FIG. 1 is a cross-sectional view of a diamond film 1 on which diamond micropillars 101 are formed according to the present invention;

FIG. 2 is a plan view of a diamond film 1 on which diamond micropillars 101 are formed according to the present invention;

FIG. 3 is a top view of a semiconductor structure of the present invention forming a first electrode 2;

FIG. 4 is a top view of a semiconductor structure of the present invention forming an insulating layer 4;

FIG. 5 is a top view of a diamond based UV detector of the present invention;

fig. 6 is a cross-sectional view of a diamond-based ultraviolet detector of the present invention.

Detailed Description

A preparation method of a diamond-based ultraviolet detector comprises the following steps:

first, a diamond film 1 is provided, which may be a substrate prepared by a high temperature and high pressure process, a substrate prepared by a CVD (chemical vapor deposition) process, or a self-supporting diamond film. The shape of the diamond film 1 is rectangular, circular, oval or other shapes. This embodiment takes a diamond film 1 having a rectangular shape as an example. The photoetching and etching processes and the devices used by the photoetching and etching processes are all available, and the used raw materials are all purchased.

Referring to fig. 1-2, the diamond film 1 is etched to form diamond micro-pillars 101 periodically arranged on the surface of the diamond film 1, gaps between the diamond micro-pillars 101 form third grooves 104, and the upper and lower sides of the third grooves 104 are communicated with first grooves 102 and second grooves 103. Specifically, the periodically arranged diamond micropillars 101 are obtained on the surface of the diamond film 1 by utilizing the photoetching and etching processes, and a first groove 102, a second groove 103 and a third groove 104 are formed at the same time. The diamond etching process includes Inductively Coupled Plasma (ICP) etching, Reactive Ion Etching (RIE), and the like. In addition, the diamond micropillars 101 in non-periodic arrangement can also be obtained on the surface of the diamond film 1 by utilizing the photoetching and etching processes. The diamond microcolumn 101 may be a rectangular parallelepiped, and the height of the diamond microcolumn 101 is 5 to 20 μm. The remaining thickness of the diamond film 1 at the bottom of the diamond micro-column 101 is less than or equal to 10 μm. The diamond microcolumn 101 has a dimension of 40 to 60 μm in width, and the third groove 104 has a dimension of 10 to 30 μm in width. The diamond microcolumn 101 with a three-dimensional structure is formed on the surface of the diamond film 1, so that the irradiated effective area of the diamond film 1 can be increased subsequently, the ultraviolet light utilization rate is improved, the generation quantity of photon-generated carriers is increased, and the sensitivity of devices is improved.

Finally, the first electrode 2, the insulating layer 4, and the second electrode 3 are sequentially deposited in the first trench 102, the second trench 103, and the third trench 104. Wherein the first electrode 2 and the second electrode 3 are partially stacked, and the portion where the first electrode 2 and the second electrode 4 are stacked is located in the third trench 104. An insulating layer 4 is formed between the stacked regions of the first electrode 2 and the second electrode 3 for isolating the first electrode 2 from the second electrode 3, and both the first electrode 2 and the second electrode 3 form ohmic contact with the diamond microcolumn 101.

Specifically, as shown in fig. 3, the first electrode 2 includes a shank and a tooth, and the first electrode 2 is deposited at the bottoms of the first trench 102 and the third trench 104. It should be noted that when depositing the first electrode 2, it is necessary to remove the surface of the diamond micro-column 101, the excess metal residue on the side wall of the third groove 104 and all the metal (the other handle) in the second groove 103 by photolithography and lift-off process, only the metal of the comb-teeth structure in the first groove 102 and the third groove 104 is remained as the first electrode 2, and the first electrode 2 can directly contact the diamond film 1 on the bottom wall of the first groove 102 and the third groove 104 and the side wall of the diamond micro-column 101.

As shown in fig. 4, an insulating layer 4 is deposited on the first electrode 2, and it is noted that, when depositing the insulating layer 4, the surface of the diamond micropillar 101, the residual of the polymer of the insulating layer 4 in the first trench 102 and the second trench 103, and the polymer of the insulating layer 4 in the third trench 104 need to be removed by using photolithography and etching processes, only the insulating layer 4 covering the tooth portion of the first electrode 2 remains, the edge of the remaining insulating layer 4 is connected to the sidewall of the diamond micropillar 101, and it is needed to ensure that the insulating layer 4 can completely isolate the first electrode 2 from the second electrode 3 subsequently.

As shown in fig. 5-6, a second electrode 3 is deposited on the insulating layer 4, similar to the first electrode 2. The second electrode 3 includes a shank and a tooth, and the second electrode 3 needs to directly contact the sidewall of the diamond microcolumn 101 to form an ohmic contact. It should be noted that, when depositing the second electrode 3, it is necessary to remove the excess metal residues on the surface of the diamond micro-pillar 101, the first trench 102, the second trench 103, and the third trench 104 by photolithography and lift-off processes, and only the metal with the comb-tooth structure on the other side opposite to the first electrode 2 (i.e. the metal above the second trench 103) is remained as the second electrode 3, so as to ensure that the second electrode 3 is disposed opposite to the first electrode 2, and that the teeth of the first electrode 2 and the teeth of the second electrode 3 are completely or partially stacked in the space above the third trench 104, and the insulating layer 4 achieves the effect of complete insulation. Preferably, after the first electrode 2 and the second electrode 3 are both prepared, the device can be placed in an argon atmosphere at 400-500 ℃ for annealing for 40-50 min, so that the ohmic characteristic of the metal electrode in contact with the diamond film 1 can be further optimized.

When the prepared diamond-based ultraviolet detector works, a bias voltage is applied between the first electrode 2 and the second electrode 3, the first electrode 2 and the second electrode 3 form a uniform electric field in the diamond film 1 through the side wall of the diamond micro-column 101, compared with the traditional planar interdigital electrode structure, the first electrode 2 and the second electrode 3 which are stacked in space are arranged by utilizing the first groove 102, the second groove 103 and the third groove 104, the area of the metal electrode occupying the surface of the diamond film 1 is at least reduced by half, namely, the light response area of the diamond film 1 (the diamond micro-column 101) irradiated is at least increased by one time, the duty ratio of the surface of the diamond film 1 is improved, the utilization rate of ultraviolet light is improved, the generation quantity of carriers is increased, the current responsivity in a device is improved, and the sensitivity and responsivity of the detector are improved. In addition, the first electrode 2 and the second electrode 3 which are stacked in space are arranged, so that the structure of the device is more three-dimensional, an electric field can be widely and uniformly distributed in the diamond microcolumn 101 and the diamond film 1, effective collection of all current carriers in the diamond film 1 is realized, and the sensitivity and the responsiveness of the detector are further improved.

The growth process of the first electrode 2 and the second electrode 3 may be a magnetron sputtering process or an electron beam evaporation process, and the growth process of the first electrode 2 and the second electrode 3 is not particularly limited, and may be a metal electrode deposition technique known to those skilled in the art. The material of the first electrode 2 and the material of the second electrode 3 can be selected from metal materials such as gold, chromium or titanium, and the first electrode 2 and the second electrode 3 made of the metal materials have good adhesion with the diamond film 1, and can form good ohmic contact with the diamond microcolumn 101.

The thickness of the teeth of the first electrode 2 and the thickness of the teeth of the second electrode 3 may be the same or different, and in this example, the thickness of the teeth of the first electrode 2 and the thickness of the teeth of the second electrode 3 are both set to 300nm to 400 nm. The material of the insulating layer 4 may be selected from insulating materials such as silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, or titanium oxide, the thickness of the insulating layer 4 may be set according to the depth of the third trench 104 and the thicknesses of the first electrode 2 and the second electrode 3, and the thickness of the insulating layer 4 may be 2 μm to 4 μm. The thicknesses of the first electrode 2, the second electrode 3 and the insulating layer 4 are set according to actual conditions, and the upper surface of the second electrode 3 can be lower than the upper surface of the diamond micro-column 101 or can be flush with the upper surface of the diamond micro-column 101.

Referring to fig. 6, the diamond-based ultraviolet detector manufactured by the above method includes a diamond film 1, a first electrode 2, a second electrode 3 and an insulating layer 4, wherein diamond micro-pillars 101 are periodically arranged on the surface of the diamond film 1, a third groove 104 is formed by a gap between the diamond micro-pillars 101, and a first groove 102 and a second groove 103 are communicated with two ends of the third groove 104. The first electrode 2 and the second electrode 3 are oppositely deposited in the first trench 102, the second trench 103, the third trench 104 and partially stacked. An insulating layer 4 is formed between the regions where the first electrode 2 and the second electrode 3 are stacked to isolate the first electrode 2 at the bottom of the third trench 104 and the second electrode 3 at the top of the third trench 104. The first electrode 2 and the second electrode 3 are both in ohmic contact with the diamond microcolumn 101.

Claims

1. A diamond based uv detector characterized by: comprises a diamond film (1), a first electrode (2), a second electrode (3) and an insulating layer (4); the diamond film (1) comprises diamond micro-columns (101), first grooves (102), second grooves (103) and third grooves (104), the diamond micro-columns (101) are periodically distributed on the surface of the diamond film (1), gaps between every two diamond micro-columns (101) are the third grooves (104), and the first grooves (102) and the second grooves (103) communicated with the third grooves (104) are respectively arranged on two sides of the third grooves (104); the first electrode (2) is arranged on the first groove (102) and the third groove (104); the second electrode (3) is arranged above the second groove (103) and the third groove (104); the insulating layer (4) is arranged between the stacked areas of the first electrode (2) and the second electrode (3).

2. The diamond based uv detector according to claim 1, wherein: the upper surface of the second electrode (3) is not higher than the upper surface of the diamond microcolumn (101).

3. The diamond based uv detector according to claim 1, wherein: the first and second electrodes (2, 3) each comprise a shank and a tooth, the teeth of the first electrode (2) and the teeth of the second electrode (3) being stacked above the third groove (104).

4. The diamond based uv detector according to claim 1, wherein: the height of the diamond microcolumn (101) is 5-20 μm, and the width is 40-60 μm.

5. The diamond based uv detector according to claim 1, wherein: the width of the third groove (104) is 10-30 mu m.

6. The diamond based uv detector according to claim 1, wherein: the thickness of the diamond film (1) is less than or equal to 10 mu m.

7. The diamond based uv detector according to claim 1, wherein: the thickness of the insulating layer (4) is 2-4 μm.

8. The diamond based uv detector according to claim 1, wherein: the insulating layer (4) is made of silicon dioxide, silicon nitride, aluminum oxide, aluminum nitride or titanium oxide materials.

9. The diamond based uv detector according to claim 1, wherein: the first electrode (2) and the second electrode (3) are made of gold, chromium or titanium materials.

10. The method for manufacturing a diamond based uv detector according to any one of claims 1 to 9, comprising the steps of:

s1: preparing a diamond film (1);

s2: etching the diamond film (1) to form a diamond micro-column (101), a first groove (102), a second groove (103) and a third groove (104) on the surface of the diamond film;

s3: and sequentially depositing a first electrode (2), an insulating layer (4) and a second electrode (3) in the first trench (102), the second trench (103) and the third trench (104), and removing redundant parts.