CN108615783B - Schottky ultraviolet detector and manufacturing method thereof - Google Patents
Schottky ultraviolet detector and manufacturing method thereof Download PDFInfo
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- CN108615783B CN108615783B CN201810356353.3A CN201810356353A CN108615783B CN 108615783 B CN108615783 B CN 108615783B CN 201810356353 A CN201810356353 A CN 201810356353A CN 108615783 B CN108615783 B CN 108615783B
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
- H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
- H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier
- H01L31/108—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier being of the Schottky type
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1828—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIBVI compounds, e.g. CdS, ZnS, CdTe
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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Abstract
The invention provides a Schottky ultraviolet detector and a manufacturing method thereof, wherein the Schottky ultraviolet detector comprises the following steps: a substrate; an ohmic contact electrode formed on a surface of the substrate; a first ZnO material layer covering the substrate and the ohmic contact electrode; the Schottky contact metal is formed on the surface of the first ZnO material layer, and comprises a bottom Schottky contact metal and a plurality of convex structures formed on the bottom Schottky contact metal; the ultraviolet detector of the invention enhances the absorption of the second ZnO material layer to ultraviolet light and the collection efficiency of photon-generated carriers, and improves the concentration of the photon-generated carriers, thereby improving the sensitivity of the detector.
Description
Technical Field
The invention relates to the technical field of ultraviolet detection, in particular to a Schottky ultraviolet detector and a manufacturing method thereof.
Background
The third generation wide band gap semiconductor material mainly comprises SiC, GaN, ZnO and diamond, and compared with the first generation semiconductor material, the third generation wide band gap semiconductor material has the characteristics of large forbidden band width, high electron drift saturation velocity, small dielectric constant, high heat conductivity coefficient and the like, and is suitable for manufacturing electronic devices with radiation resistance, high frequency, high power and high density integration. And by utilizing the special wide forbidden band, a light emitting device and a light detecting device of blue light, green light and ultraviolet light can be manufactured.
The ultraviolet detection technology has wide application in the fields of high-temperature flame detection, ultraviolet communication, biochemical substance detection, space detection and the like. The core of the ultraviolet detection technology is an ultraviolet detector, which is a sensor for converting one form of electromagnetic radiation signal into another form of signal which can be easily received and processed, and converts optical radiation into an electrical signal by using the photoelectric effect. The main parameters of the ultraviolet detector include dark current, photocurrent, responsivity, quantum efficiency, response time and the like.
ZnO is a novel II-VI family direct band gap wide band gap compound semiconductor material, and the band gap width is 3.37eV at room temperature. The ZnO and the GaN are both hexagonal wurtzite structures, have similar lattice constants and forbidden band widths, and the ZnO has higher melting point and exciton confinement energy, and good electromechanical coupling and electron-induced defects. In addition, the epitaxial growth temperature of the ZnO film is lower, which is beneficial to reducing the equipment cost, inhibiting solid phase epitaxy, improving the film quality and easily realizing doping.
The excellent characteristics of the ZnO film enable the ZnO film to be widely applied to various fields such as ultraviolet detection, surface acoustic wave devices, solar cells, variable resistors and the like. And the ZnO film sensor has the advantages of high response speed, high integration degree, low power, high sensitivity, good selectivity, low cost and easy obtainment of raw materials and the like.
The n-type zinc oxide Schottky ultraviolet detector is one of the mainstream ultraviolet detectors at present, integrates high responsivity and low dark current, and has the advantages of short response time, high quantum efficiency and the like.
However, the current schottky ultraviolet detector still has the following problems:
1. since light must be incident through the metal electrode or through the back surface of the substrate when the light irradiates the semiconductor, the incident light is greatly lost. However, since most semiconductors absorb very strongly in the ultraviolet band, and the absorption coefficient is generally large, a good anti-reflection layer is usually used, so that most of the light absorption is fully achievable near the surface junction, but due to the introduction of the anti-reflection layer, the process steps are increased.
2. The junction formed by the metal-semiconductor contact is relatively shallow, mainly near the semiconductor surface. Photogenerated carriers generated deep in a semiconductor are difficult to be effectively collected.
In view of the above problems, it is desirable to provide a new schottky ultraviolet detector and a manufacturing method thereof to solve the above problems.
Disclosure of Invention
In this summary, concepts in a simplified form are introduced that are further described in the detailed description. This summary of the invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
In view of the problems existing at present, the present invention provides, in one aspect, a schottky ultraviolet detector, including:
a substrate;
an ohmic contact electrode formed on a surface of the substrate;
a first ZnO material layer covering the substrate and the ohmic contact electrode;
the Schottky contact metal is formed on the surface of the first ZnO material layer, and comprises a bottom Schottky contact metal and a plurality of convex structures formed on the bottom Schottky contact metal;
and the second ZnO material layer covers the Schottky contact metal.
Illustratively, the raised structures are arranged in an array; the shape of the convex structure is a strip shape or a column shape.
Illustratively, the material of the first ZnO material layer includes n-type ZnO or intrinsic ZnO; the material of the second ZnO material layer comprises n-type ZnO or intrinsic ZnO.
The ohmic contact metal window penetrates through the second ZnO material layer and the first ZnO material layer in sequence to expose part of the ohmic contact electrode, or the ohmic contact metal window penetrates through the substrate to expose part of the ohmic contact electrode, or the substrate is an ohmic contact metal plate and is used for being electrically connected with the ohmic contact electrode.
Illustratively, the ohmic contact metal windows are disposed at corner regions of the substrate.
Exemplarily, the method further comprises the following steps: and the Schottky contact metal window penetrates through the second ZnO material layer to expose part of the Schottky contact metal and is used for electrically connecting the Schottky contact metal with an external circuit.
Illustratively, gaps or mutual contact exist between the second ZnO material layers on the side walls of the adjacent protruding structures.
In another aspect, the present invention further provides a method for manufacturing a schottky ultraviolet detector, including:
providing a substrate, and forming an ohmic contact electrode on the surface of the substrate;
forming a first ZnO material layer to cover the substrate and the ohmic contact electrode;
forming Schottky contact metal on the surface of the first ZnO material layer, wherein the Schottky contact metal comprises bottom Schottky contact metal and a plurality of convex structures formed on the bottom Schottky contact metal;
and forming a second ZnO material layer on the surface of the bottom Schottky contact metal and the surface of the protruding structure.
Illustratively, the step of forming the schottky contact metal includes:
forming a Schottky contact metal material layer on the surface of the first ZnO material layer;
forming a patterned mask layer on the Schottky contact metal material layer, wherein the patterned mask layer is defined with a pattern of the projection structure which is formed in advance;
etching part of the Schottky contact metal material layer to stop in the Schottky contact metal material layer by taking the patterned mask layer as a mask so as to form the protruding structure, wherein the Schottky contact metal material layer below the protruding structure is used as the bottom Schottky contact metal;
and removing the patterned mask layer.
For example, after forming the schottky contact metal material layer and before forming the patterned mask, or after removing the patterned mask layer and before forming the second ZnO material layer, the method further includes:
and etching and removing part of the edge of the Schottky metal material layer to expose part of the first ZnO material layer.
Illustratively, after forming the first ZnO material layer, an ohmic contact metal window exposing a portion of the ohmic contact electrode is formed, wherein,
the method for forming the ohmic contact metal window comprises the following steps:
coating a photoresist layer on the surface of the ohmic contact electrode;
patterning the photoresist layer through a photolithography process to form an ohmic contact metal window pattern;
and after the first ZnO material layer is formed, removing the photoresist layer to form the ohmic contact metal window, or after the second ZnO material layer is formed, removing the photoresist layer to form the ohmic contact metal window.
Illustratively, after forming the ohmic contact electrode, further comprising:
and forming an ohmic contact metal window in the surface of the substrate opposite to the ohmic contact electrode, wherein the ohmic contact metal window penetrates through the substrate to expose part of the ohmic contact electrode.
Illustratively, after forming the second ZnO material layer, the method further includes forming a schottky contact metal window exposing a portion of the schottky contact metal, and the method of forming the schottky contact metal window includes:
forming a patterned mask layer on the surface of the second ZnO material layer, wherein the mask layer is defined with the shape of a Schottky contact metal window which is formed in advance;
etching the second ZnO material layer by taking the patterned mask layer as a mask until part of the surface of the Schottky contact metal is exposed so as to form a Schottky contact metal window;
and removing the patterned mask layer.
Illustratively, after forming the second ZnO material layer, the method further includes forming a schottky contact metal window exposing a portion of the schottky contact metal, and the method of forming the schottky contact metal window includes:
forming a photoresist layer to cover one surface of the substrate, on which the Schottky contact metal is formed;
patterning the photoresist layer through a photoetching process to form a Schottky contact metal window shape;
after the second ZnO material layer is formed, the photoresist layer is removed to form the Schottky contact metal window.
Illustratively, the shape of the protruding structure is a long strip or a column; the protruding structures are arranged in an array.
Illustratively, the material of the first ZnO material layer includes n-type ZnO or intrinsic ZnO; the material of the second ZnO material layer comprises n-type ZnO or intrinsic ZnO.
Illustratively, the substrate is an ohmic contact metal plate for electrical connection with the ohmic contact electrode.
Illustratively, gaps or mutual contact exist between the second ZnO material layers on the side walls of the adjacent protruding structures.
The Schottky contact metal in the Schottky barrier ultraviolet detector comprises the plurality of protruding structures, the specific surface areas of the Schottky contact metal and the second ZnO material layer covering the Schottky contact metal are increased, the absorption of the second ZnO material layer on ultraviolet light and the collection efficiency of photon-generated carriers are enhanced, the concentration of the photon-generated carriers is improved, and therefore the sensitivity of the detector is improved.
Drawings
The following drawings of the invention are included to provide a further understanding of the invention. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
In the drawings:
FIG. 1 shows a schematic cross-sectional view of a conventional GaN Schottky ultraviolet detector;
FIG. 2 shows a current TiO2A schematic cross-sectional view of a nano-particle modified ZnO Schottky ultraviolet detector;
fig. 3A to 3D are schematic views showing structures obtained by sequentially performing the method according to one embodiment of the present invention, wherein the left side view is a cross-sectional view and the right side view is a top view;
fig. 4 shows a flow chart of a method of manufacturing a schottky uv detector according to an embodiment of the present invention.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.
It is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like reference numerals refer to like elements throughout.
It will be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it can be directly on, adjacent to, connected or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
Spatial relational terms such as "under," "below," "under," "above," "over," and the like may be used herein for convenience in describing the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "under" and "under" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
In the following description, for purposes of explanation, specific details are set forth in order to provide a thorough understanding of the present invention. The following detailed description of the preferred embodiments of the invention, however, the invention is capable of other embodiments in addition to those detailed.
The schottky ultraviolet detector commonly used at present mainly comprises the following types: the first is a conventional GaN schottky uv detector, as shown in fig. 1, which includes an i-GaN layer below a schottky electrode and an n-GaN (i.e., an ohmic contact layer) below the i-GaN layer, and which generates photogenerated carriers by passing uv light into an intrinsic GaN epitaxial layer through the schottky electrode on the top layer, and the photogenerated carriers are collected to generate a photocurrent. The second is TiO2A nano-particle modified ZnO Schottky ultraviolet detector is shown in figure 2, wherein an electrode 2 is formed on a substrate 1, the substrate 1 and the electrode 2 are covered by a ZnO film 3, and a ZnO nano-pillar array 4 and TiO are grown on the ZnO film2Modifying ZnO nano-column array 4 with nano-particles 5 by TiO2The modification of the surface of ZnO improves the influence of the oxygen vacancy trap state on the surface of ZnO. The third is a ZnO Schottky ultraviolet detector, such as an Ag/ZnO Schottky ultraviolet detector.
However, the current schottky ultraviolet detector still has the following problems:
1. since light must be incident through the metal electrode or through the back surface of the transparent substrate when the light irradiates the semiconductor, the incident light is greatly lost. However, since most semiconductors absorb very strongly in the ultraviolet band, and the absorption coefficient is generally large, a good anti-reflection layer is usually used, so that most of the light absorption is fully achievable near the surface junction, but due to the introduction of the anti-reflection layer, the process steps are increased.
2. The junction formed by the metal-semiconductor contact is relatively shallow, mainly near the semiconductor surface. Photogenerated carriers generated deep in a semiconductor are difficult to be effectively collected.
Example one
In view of the technical problems of the schottky barrier uv detector, the present invention provides an improved schottky barrier uv detector, which mainly comprises:
a substrate;
an ohmic contact electrode formed on a surface of the substrate;
a first ZnO material layer covering the substrate and the ohmic contact electrode;
the Schottky contact metal is formed on the surface of the first ZnO material layer, and comprises a bottom Schottky contact metal and a plurality of convex structures formed on the bottom Schottky contact metal;
and the second ZnO material layer covers the Schottky contact metal.
The Schottky contact metal in the Schottky barrier ultraviolet detector comprises a plurality of protruding structures, the specific surface area of the Schottky contact metal and the second ZnO material layer covering the Schottky contact metal is increased, the concentration of photon-generated carriers is improved, and therefore the sensitivity of the detector is improved.
Next, the schottky ultraviolet detector of the present invention will be described in detail with reference to fig. 3D. The left cross-sectional view in fig. 3D is a cross-sectional view of the device taken along the cross-sectional line AA' in the right top view.
Illustratively, as shown in fig. 3D, the schottky ultraviolet detector of the present invention includes a substrate 100.
Specifically, the substrate 100 may be any substrate suitable for an ultraviolet detector, for example, the material of the substrate 100 includes at least one of silicon carbide, sapphire, and aluminum nitride.
In one example, the schottky ultraviolet detector of the present invention further includes an ohmic contact electrode 101, and the ohmic contact electrode 101 is formed on the surface of the substrate 100, wherein the ohmic contact electrode 101 may cover the entire surface of the substrate 100 as illustrated in fig. 3D, or the ohmic contact electrode may cover only a part of the surface of the substrate 100.
Illustratively, the thickness of the ohmic contact electrode may be any suitable thickness, for example, the thickness of the ohmic contact electrode is below 5 μm.
Further, the schottky ultraviolet detector of the present invention further includes a first ZnO material layer 102, where the first ZnO material layer 102 is formed on the surface of the ohmic contact electrode 101, and when the ohmic contact electrode 101 covers the entire surface of the substrate 100, the first ZnO material layer 102 may cover the entire surface of the ohmic contact electrode, or when the ohmic contact electrode covers a portion of the surface of the substrate 100, the first ZnO material layer covers the exposed substrate and the ohmic contact electrode. .
The thickness of the first ZnO material layer may be any suitable thickness, for example, the thickness of the first ZnO material layer may be 500nm or less.
Illustratively, the material of the ohmic contact electrode 101 may be any metal material capable of forming an ohmic contact with the first ZnO material layer 102, for example, the material of the ohmic contact electrode includes Ti, Al or TiAl alloy.
Illustratively, the material of the first ZnO material layer 102 may be replaced by any other suitable wide bandgap semiconductor material (e.g., Eg greater than or equal to 2.3eV), also referred to as a third generation semiconductor material, e.g., may be replaced by at least one of silicon carbide, gallium nitride, diamond, and aluminum nitride.
In one example, the material of the first ZnO material layer 102 comprises n-type ZnO. Optionally, the material of the first ZnO material layer 102 may further include intrinsic ZnO (i.e., i-type ZnO), i.e., zinc oxide formed by non-external doping, where intrinsic ZnO prepared by conventional processes is n-type conductivity, e.g., ZnO grown by Physical Vapor Deposition (PVD) or Pulsed Laser Deposition (PLD), has abundant oxygen vacancies and interstitial zinc, which is the main reason for n-type conductivity.
Illustratively, the N-type ZnO is doped with an N-type dopant, wherein the N-type dopant includes at least one of B, Al, Ga, In, Si, Ti, Ge, Zr, Sn, Hf, Pb, La, and Pr.
The first ZnO material layer 102 is in ohmic contact with an ohmic contact electrode, and serves as an ohmic contact electrode of the schottky ultraviolet detector, and the first ZnO material layer 102 also serves as a conductive layer for conducting photo-generated electrons and holes generated by absorption of light by the second ZnO material layer.
In one example, the schottky ultraviolet detector of the present invention further comprises a schottky contact metal 103 formed on the surface of the first ZnO material layer 102, wherein the schottky contact metal 103 comprises a bottom schottky contact metal 1032 and a plurality of protruding structures 1031 formed on the bottom schottky contact metal.
Illustratively, the protruding structures 1031 have an elongated shape or a cylindrical shape, such as a cylindrical shape, or may have another suitable shape, such as a conical shape.
In one example, the raised structures 1031 are arranged in an array on the bottom schottky contact metal 1032.
In one example, the raised structures are perpendicular to the surface of the bottom schottky contact metal.
In one example, the depth of the trenches between adjacent raised structures 1031 is less than 8 μm, which is only an example, and other suitable depths are equally applicable to the present invention.
It should be noted that the distance between adjacent protruding structures is set according to the thickness of the formed depletion layer, when the schottky contact metal 103 contacts the second ZnO material layer 104, because the energy levels of the carriers are different, they will move toward the low level direction, so that a barrier layer (i.e., a depletion layer) is formed in the contact region, therefore, the larger the predetermined depletion layer thickness is, the larger the thickness of the second ZnO material layer is, and therefore, the distance between the protruding structures is correspondingly larger, so as to meet the requirement.
In one example, the bottom schottky contact metal 1032 covers a portion of the first ZnO material layer 102, e.g., the bottom schottky contact metal 1032 covers a central region of the first ZnO material layer 102.
Since the schottky contact metal 103 includes the plurality of bump structures 1031, the specific surface area of the schottky contact metal 103 is significantly increased compared to a planar schottky contact metal that does not include the bump structures 1031.
In one example, the schottky ultraviolet detector of the present invention further includes a second ZnO material layer 104, where the second ZnO material layer 104 is formed on the surface of the bottom schottky contact metal 1032 and the surface of the protruding structure 1031, that is, the second ZnO material layer covers the schottky contact metal 103.
In one example, the material of the second ZnO material layer 104 may also be replaced by other suitable semiconductor materials, in particular including a wide bandgap semiconductor material, wherein the wide bandgap semiconductor material includes at least one of silicon carbide, gallium nitride, diamond and aluminum nitride.
Illustratively, the material of the second ZnO material layer 104 includes n-type ZnO, wherein the ZnO is doped with an n-type dopant, and the specific type of the n-type dopant may refer to the foregoing description, and is not repeated herein to avoid repetition. Optionally, the material of the second ZnO material layer 104 may also include intrinsic ZnO, that is, zinc oxide formed by non-external doping. It should be noted that the first ZnO material layer and the second ZnO material layer may be made of the same semiconductor material or different semiconductor materials.
The thickness of the second ZnO material layer 104 may be any suitable thickness, for example, as shown in fig. 3D, there is a gap between the second ZnO material layers 104 on the sidewalls of the adjacent protruding structures 1031 to ensure that there is more area of the second ZnO material layer contacting light when light irradiates the second ZnO material layer 104, or the second ZnO material layers on the sidewalls of the adjacent protruding structures contact each other, that is, the second ZnO material layers completely cover the schottky contact metal and fill the gap between the adjacent protruding structures.
A passivation layer (not shown) may be optionally disposed on the surface of the second ZnO material layer 104 for protecting the device, wherein the material of the passivation layer may be any suitable insulating layer, such as an inorganic insulating layer of a silicon oxide layer, a silicon nitride layer, or a silicon oxynitride layer, an insulating layer including a layer of polyvinylphenol, polyimide, siloxane, or the like. In this embodiment, preferably, the material of the passivation layer includes silicon oxide.
In one example, any metal material capable of forming a schottky barrier with the second ZnO material layer 104 may be used as the material of the schottky contact metal 103, for example, the schottky contact metal 103 is a high work function metal, for example, a metal material with a work function greater than 5eV, and optionally, the material of the schottky contact metal 103 includes at least one of Au, Pt, Pd, Ni, and W.
In one example, the work function of the schottky contact metal 103 is greater than the work function of the ohmic contact electrode 101.
In one example, as shown in the right-side plan view of fig. 3D, in order to facilitate connection of the ohmic contact electrode to an external circuit to lead out the ohmic contact electrode of the schottky ultraviolet detector, the schottky ultraviolet detector of the present invention further includes an ohmic contact metal window 105, where the ohmic contact metal window 105 exposes a portion of the ohmic contact electrode 101, for example, the ohmic contact metal window penetrates through the second ZnO material layer 104 and the first ZnO material layer 102, and when a passivation layer is disposed on a surface of the second ZnO material layer 104, the ohmic contact metal window penetrates through the passivation layer, the second ZnO material layer 104 and the first ZnO material layer 102 in sequence to expose a portion of the ohmic contact electrode 101.
In one example, the location of the ohmic contact metal windows 105 may be disposed at any suitable location, with the ohmic contact metal windows preferably being disposed at corner regions of the substrate.
In one example, the ohmic contact metal window may be further disposed on a back surface of the substrate, where a portion of the ohmic contact electrode is exposed through the substrate, and the back surface is opposite to a surface of the substrate on which the ohmic contact electrode is formed.
The top view shape of the ohmic contact metal window may be any shape, such as a rectangle, a circle, a triangle, or other polygons.
In one example, in order to facilitate electrical connection between the ohmic contact electrode and an external circuit, the substrate 100 may be an ohmic contact metal plate, for example, the ohmic contact metal plate may include the same metal material as the ohmic contact electrode 101, for example, the ohmic contact metal plate includes Ti, Al or TiAl alloy, or, when the substrate is an ohmic contact metal plate, the ohmic contact electrode may be a portion of the ohmic contact metal plate, which is in contact with the first ZnO material layer to form ohmic contact.
In one example, as shown in the right side top view of fig. 3D, the schottky contact metal window 106 of the present invention further includes a schottky contact metal window 106, which penetrates through the second ZnO material layer 104 to expose a portion of the schottky contact metal 103 for electrical connection of the schottky contact metal with an external circuit, and when a passivation layer is disposed on the surface of the second ZnO material layer 104, the schottky contact metal window 106 also penetrates through the passivation layer.
The schottky contact metal window 106 may be located at any position, but it is necessary to ensure that a part of the schottky contact metal is exposed from the schottky contact metal window 106.
Illustratively, in order to realize the electrical connection of the schottky contact metal and the ohmic contact electrode with an external circuit, metal interconnection lines electrically connected with the schottky contact metal and the ohmic contact electrode respectively can be further provided.
It should be noted that, in the present embodiment, the schottky ultraviolet detector structure of the present invention is explained and illustrated by taking n-type ZnO as an example, and other p-type semiconductor materials, especially p-type wide bandgap semiconductor materials, such as p-type semiconductor materials, are also applicable to the present invention.
The description of the key components of the schottky ultraviolet detector structure of the present invention is completed so far, and the complete structure may further include other constituent elements, which are not described in detail herein.
In summary, in the schottky ultraviolet detector structure of the present invention, since the second ZnO material layer covers the schottky contact metal 103, light can directly irradiate the second ZnO material layer without great loss, and even when the anti-reflection layer is not provided, most of the light absorption can be achieved near the surface junction. When the schottky contact metal 103 is in contact with the second ZnO material layer 104, carriers will move to a lower level due to their different energy levels, thereby forming a barrier layer (depletion layer) in the contact region. The positive charges in the barrier layer and the negative charges of the metal contact surface form an electric dipole layer-contact barrier, i.e. a schottky barrier. Due to the existence of the built-in electric field of the schottky barrier, when the second ZnO material layer 104 is illuminated, photo-generated electrons and holes are generated due to absorption of light by the second ZnO material layer 104, and they move and accumulate in opposite directions under the action of the built-in electric field to generate a dot difference. The specific surface area of the schottky contact metal 103 is increased, the specific surface area of the second ZnO material layer covering the schottky contact metal 103 is correspondingly increased, and when the second ZnO material layer is irradiated by light, the area of the second ZnO material layer where the light reaches is correspondingly increased, so that the absorption of the second ZnO material layer to the light and the collection efficiency of a photon-generated carrier are increased, the concentration of the photon-generated carrier is improved, and the sensitivity of the schottky ultraviolet detector is further improved.
Example two
The invention further provides a manufacturing method of the schottky ultraviolet detector in the first embodiment, as shown in fig. 4, which mainly includes the following steps:
step S1, providing a substrate, and forming an ohmic contact electrode on the surface of the substrate;
step S2, forming a first ZnO material layer covering the substrate and the ohmic contact electrode;
step S3, forming schottky contact metal on the surface of the first ZnO material layer, wherein the schottky contact metal includes bottom schottky contact metal and a plurality of protruding structures formed on the bottom schottky contact metal;
step S4, forming a second ZnO material layer on the surface of the bottom schottky contact metal and the surface of the protrusion structure.
Next, a method for manufacturing the schottky ultraviolet detector of the present invention will be explained and explained in detail with reference to fig. 3A to 3D and fig. 4.
Specifically, first, step one is performed, as shown in fig. 3A, a substrate 100 is provided, and an ohmic contact electrode 101 is formed on a surface of the substrate 100.
Illustratively, the substrate 100 may be any substrate suitable for use in an ultraviolet detector, for example, the material of the substrate 100 includes at least one of silicon carbide, sapphire, and aluminum nitride.
In one example, before forming the ohmic contact electrode, further comprising: and cleaning the substrate.
Depending on the material of the substrate, the substrate may be cleaned using any suitable cleaning method, for example, acetone, ethanol, deionized water; or, cleaning the substrate by using hydrochloric acid, ethanol and deionized water; or cleaning the substrate by using acetone, ethanol and isopropanol.
In one example, for a sapphire substrate (Al)2O3) The GaN single crystal substrate is cleaned by the following steps: at H2SO4: heating in acid with the HCl volume ratio of 3:1 for 15-45 min, then ultrasonically cleaning in acetone and isopropanol (or propanol) for 10-50 min, then washing with deionized water, finally blowing and drying with a nitrogen gun, then placing into a growth chamber, treating in the growth chamber at a high temperature of 300-800 ℃ for 10-50 min, and removing water vapor and organic matters on the surface.
The material of the ohmic contact electrode 101 may be any metal material capable of forming ohmic contact with the first ZnO material layer 102 formed later, for example, the material of the ohmic contact electrode includes Ti, Al or TiAl alloy.
Illustratively, the thickness of the ohmic contact electrode may be any suitable thickness, for example, the thickness of the ohmic contact electrode is below 5 μm.
The ohmic contact electrode may be formed using any suitable deposition method, for example by electron beam evaporation, magnetron sputtering or physical vapour deposition.
In one example, in order to facilitate electrical connection between the ohmic contact electrode and an external circuit, the substrate 100 may be an ohmic contact metal plate, for example, the ohmic contact metal plate may include the same metal material as the ohmic contact electrode 101, for example, the ohmic contact metal plate includes Ti, Al or TiAl alloy, or, when the substrate is an ohmic contact metal plate, the ohmic contact electrode may be a portion of the ohmic contact metal plate, which is in contact with a first ZnO material layer to be formed later, to form ohmic contact.
In another example, the ohmic contact electrode 101 may also cover a portion of the substrate 100, for example, a layer of ohmic contact electrode material is deposited to cover the surface of the substrate 100, and then the layer of ohmic contact electrode material is patterned by photolithography and etching processes to form the ohmic contact electrode 101 covering a portion of the substrate 100.
In still another example, an ohmic contact electrode may also be formed to cover the entire surface of the substrate 100.
Subsequently, step two is performed, as shown in fig. 3B, a first ZnO material layer 102 is formed to cover the substrate 100 and the ohmic contact electrode 101.
Specifically, the first ZnO material layer 102 may be replaced by any other suitable semiconductor material, such as a material capable of forming an ohmic contact with the ohmic contact electrode.
Preferably, the first ZnO material layer 102 may be replaced by other wide bandgap semiconductor materials, for example, the wide bandgap semiconductor material includes at least one of silicon carbide, gallium nitride, diamond and aluminum nitride, and in this embodiment, the method of the present invention is mainly explained and illustrated by taking a case that the material of the first ZnO material layer includes n-type zinc oxide as an example.
In one example, the material of the first ZnO material layer includes n-type ZnO. Alternatively, the material of the first ZnO material layer 102 may also include intrinsic ZnO, i.e., zinc oxide formed by non-external doping, which is n-type conductivity prepared by conventional processes, such as ZnO grown by Physical Vapor Deposition (PVD) or Pulsed Laser Deposition (PLD), and has abundant oxygen vacancies and interstitial zinc, which is the main reason for n-type conductivity.
Wherein the n-type ZnO is doped with n-type dopant, and the n-type dopant comprises at least one of B, Al, Ga, In, Si, Ti, Ge, Zr, Sn, Hf, Pb, La and Pr.
The first ZnO material layer 102 may be formed by any suitable deposition method, such as physical vapor deposition, sol-gel method, Molecular Beam Epitaxy (MBE), pulsed laser deposition, or metal organic chemical vapor deposition, among others, to form the first ZnO material layer 102.
In one example, n-type ZnO is formed using a magnetron sputtering process, in whichMaintaining a high degree of vacuum in the process, e.g. with an initial pressure of less than or equal to 1X 10-4Pa, working pressure at 1 × 10-1Pa, using rare gas such as argon as protective gas, oxygen as reaction gas, radio frequency between 5 and 30MHz, the metal growth source for sputtering can be high-purity Zn or ZnO ceramic target material, and the doping source of n-type dopant can be metal source, such as Al, Ga metal source.
The thickness of the grown first ZnO material layer is reasonably selected according to specific device requirements, for example, the thickness of the first ZnO material layer 102 is below 500 nm.
In one example, in order to form an ohmic contact resistance between the first ZnO material layer and the ohmic contact electrode, an annealing step is further included, wherein the annealing temperature may be 200 to 800 ℃, and the annealing time may be 0.5 to 10min, for example, 1min, 2min, 3min, 4min, 5min, and the like.
The first ZnO material layer 102 forms an ohmic contact with the ohmic contact electrode 101, and serves as an ohmic contact electrode of the schottky ultraviolet detector, and the first ZnO material layer 102 also serves as a conductive layer for conducting photo-generated electrons and holes generated by the absorption of light by the second ZnO material layer.
In one example, as shown in fig. 3B, after forming the first ZnO material layer 102, forming an ohmic contact metal window 105 exposing a portion of the ohmic contact electrode 101 is further included.
Illustratively, the method of forming the ohmic contact metal window includes: first, a photoresist layer (not shown) is coated on a surface of the ohmic contact electrode 101; patterning the photoresist layer through a photolithography process to form an ohmic contact metal window pattern; in the subsequent process of forming the first ZnO material layer, the ohmic contact metal window pattern plays a role in protection and blocking, and the first ZnO material layer is prevented from growing in the area covered by the ohmic contact metal window pattern; and removing the ohmic contact metal window pattern after the first ZnO material layer is formed to form the ohmic contact metal window, or removing the ohmic contact metal window pattern after the second ZnO material layer is formed subsequently to form the ohmic contact metal window.
In another example, the ohmic contact metal window may be further formed by a method including: after the ohmic contact electrode is formed, forming an ohmic contact metal window in the surface of the substrate opposite to the ohmic contact electrode, wherein the ohmic contact metal window penetrates through the substrate to expose part of the ohmic contact electrode, a patterned mask layer can be formed on the back surface of the substrate, the pattern of the ohmic contact metal window is defined, the patterned mask layer is used as a mask, the substrate is etched until part of the ohmic contact electrode is exposed to form the ohmic contact metal window, and finally the patterned mask layer is removed.
Subsequently, step three is executed, as shown in fig. 3C, a schottky contact metal 103 is formed on the surface of the first ZnO material layer 102, wherein the schottky contact metal 103 includes a bottom schottky contact metal 1032, and a plurality of protruding structures 1031 formed on the bottom schottky contact metal 1032.
In one example, the material of the schottky contact metal 103 may use any metal material capable of forming a schottky barrier with the second ZnO material layer 104, for example, when the second ZnO material layer is predetermined to be formed as n-type ZnO, the schottky contact metal 103 is preferably a high work function metal, for example, a metal material with a work function greater than 5eV, and optionally, the material of the schottky contact metal 103 includes at least one of Au, Pt, Pd, Ni and W.
In one example, the work function of the schottky contact metal 103 is greater than that of the ohmic contact electrode 101, for example, for forming ohmic contact, when the first ZnO material layer is n-type ZnO, the ohmic contact electrode 101 preferably uses a metal with a smaller work function, for example, a metal material with a work function lower than 4.2eV, and when the second ZnO material layer is n-type ZnO, the schottky contact metal 103 preferably uses a metal material with a high work function, for example, a metal material with a work function greater than 5 eV.
The schottky contact metal 103 may be formed using any suitable method, and in one example, the step of forming the schottky contact metal 103 includes:
first, a schottky contact metal material layer is formed on the surface of the first ZnO material layer 102, and the schottky contact metal material layer may be formed by any suitable deposition method, for example, by electron beam evaporation, magnetron sputtering or physical vapor deposition, and the thickness of the schottky contact metal material layer is properly set according to the sum of the height of the bump structure to be formed and the thickness of the bottom schottky contact metal, for example, the thickness of the schottky contact metal material layer is less than 9 μm.
Then, forming a patterned mask layer, such as a photoresist layer, on the schottky contact metal material layer, wherein the patterned mask layer defines a pattern of the protrusion structure to be formed;
then, with the patterned mask layer as a mask, etching a part of the schottky contact metal material layer to stop in the schottky contact metal material layer to form the bump structure 1031, wherein the schottky contact metal material layer under the bump structure 1031 serves as the bottom schottky contact metal 1032; the etching process in this step may use a dry etching process, which includes but is not limited to: reactive Ion Etching (RIE), ion beam etching, plasma etching, or laser cutting. Preferably, the dry etching is performed by one or more RIE steps. The etching depth can be reasonably adjusted according to actual device requirements. And finally, removing the patterned mask layer.
It should be noted that the distance between adjacent protruding structures is set according to the thickness of the formed depletion layer, when the schottky contact metal 103 contacts the second ZnO material layer 104, because the energy levels of the carriers are different, they will move toward the low level direction, so that a barrier layer (i.e., a depletion layer) is formed in the contact region, therefore, the larger the predetermined depletion layer thickness is, the larger the thickness of the second ZnO material layer is, and therefore, the distance between the protruding structures is correspondingly larger, so as to meet the requirement.
Illustratively, the protruding structures 1031 have an elongated shape or a cylindrical shape, such as a cylindrical shape, or may have other suitable shapes, such as a circular truncated cone.
In one example, the raised structures 1031 are arranged in an array on the bottom schottky contact metal 1032.
In one example, the depth of the trenches between adjacent raised structures 1031 is less than 8 μm, which is only an example, and other suitable depths are equally applicable to the present invention.
In one example, after forming the schottky contact metal material layer and before forming the patterned mask, or after removing the patterned mask layer and before forming the second ZnO material layer, the method further includes: a portion of the edge of the schottky metal material layer is etched away to expose a portion of the first ZnO material layer, so that the finally formed bottom schottky contact metal 1032 covers a portion of the first ZnO material layer 102, for example, the bottom schottky contact metal 1032 covers a central region of the first ZnO material layer 102. The edge of the Schottky contact metal is removed, so that the second ZnO material layer 104 formed subsequently is contacted with the first ZnO material layer 102 at the edge, and can be regarded as an integral ZnO material layer, and an ohmic contact electrode can be arranged below the first ZnO material layer 102, compared with a method for arranging the ohmic contact electrode above the ZnO material layer at the top layer, the ohmic contact electrode does not need to be formed on the formed ZnO material layer and etched and patterned, the process is simpler, the problems of damage and the like caused by etching to the ZnO material layer can be avoided, the yield and the reliability of the device can be improved, the ohmic contact electrode is arranged below the first ZnO material layer, the shielding of the first ZnO material layer to the light can be avoided, the absorption of the second ZnO material layer to the light can be increased, and the concentration of photon-generated carriers can be improved, the sensitivity of the detector is improved.
Since the schottky contact metal 103 includes the plurality of bump structures 1031, the specific surface area of the schottky contact metal 103 is significantly increased compared to a planar schottky contact metal that does not include the bump structures 1031.
It should be noted that, in the process of forming the schottky contact metal, the ohmic contact metal window may be kept from being covered by the schottky contact metal by the method of forming the ohmic contact metal window, which is not described herein again.
Subsequently, step four is performed, as shown in fig. 3D, a second ZnO material layer 104 is formed on the surface of the bottom schottky contact metal 1032 and the surface of the protruding structure 1031.
In one example, the second ZnO material layer 104 may be replaced by any other suitable semiconductor material, particularly including a wide bandgap semiconductor material including at least one of silicon carbide, gallium nitride, diamond, and aluminum nitride.
Illustratively, the material of the second ZnO material layer 104 includes n-type ZnO, wherein the ZnO is doped with an n-type dopant, and the specific type of the n-type dopant may refer to the foregoing description, and is not repeated herein to avoid repetition. Optionally, the material of the second ZnO material layer 104 may also include intrinsic ZnO, that is, zinc oxide formed by non-external doping. It should be noted that the first ZnO material layer and the second ZnO material layer may be made of the same semiconductor material or different semiconductor materials.
The thickness of the second ZnO material layer 104 may be any suitable thickness, and for example, as shown in fig. 3D, a gap exists between the second ZnO material layers 104 on the sidewalls of the adjacent protruding structures 1031 to ensure that when light irradiates the second ZnO material layer 104, the second ZnO material layer can have more area to contact with the light, or the second ZnO material layers 104 on the sidewalls of the adjacent protruding structures 1031 contact with each other.
The second ZnO material layer 104 may be formed by any suitable deposition method, for example, physical vapor deposition, sol-gel method, Molecular Beam Epitaxy (MBE), pulsed laser deposition, or metal organic chemical vapor deposition, etc. to form the second ZnO material layer 104.
In one example, n-type ZnO is formed as the second ZnO material layer 104 using a magnetron sputtering method, with a high degree of vacuum maintained during magnetron sputtering, e.g., an initial pressure of 1 × 10 or less-4Pa, working pressure at 1 × 10-1Pa, using rare gas such as argon as protective gas, oxygen as reaction gas, radio frequency between 5 and 30MHz, the metal growth source for sputtering can be high-purity Zn or ZnO ceramic target material, and the doping source of n-type dopant can be metal source, such as Al, Ga metal source.
In one example, after forming the second ZnO material layer 104, as shown in fig. 3D, a step of forming a schottky contact metal window 106 exposing a portion of the schottky contact metal 103 is further included.
The schottky contact metal window 106 may be formed using any suitable method, and illustratively, the method of forming the schottky contact metal window 106 includes: forming a patterned mask layer on the surface of the second ZnO material layer, wherein the mask layer is defined with the shape of a Schottky contact metal window which is formed in advance; etching the second ZnO material layer by taking the patterned mask layer as a mask until part of the surface of the Schottky contact metal is exposed so as to form a Schottky contact metal window; and removing the patterned mask layer.
In another example, after forming the second ZnO material layer 104, an ohmic contact metal window may be formed by an etching method, including: forming a patterned mask layer, such as a patterned photoresist layer, on the surface of the second ZnO material layer 104, wherein a pattern of an ohmic contact metal window is defined, then, etching the second ZnO material layer 104, the schottky contact metal 103 and the first ZnO material layer 102 with the patterned mask layer as a mask until a part of the ohmic contact electrode 101 is exposed to form an ohmic contact metal window, and finally removing the patterned mask layer.
In another example, a method of forming the schottky contact metal window 106 includes: forming a photoresist layer to cover the surface of the substrate on which the Schottky contact metal is formed, namely the surface of the substrate on which the Schottky contact metal is formed; patterning the photoresist layer through a photoetching process to form a Schottky contact metal window pattern and an ohmic contact metal window pattern; the schottky contact metal window pattern is used to prevent a subsequently deposited second ZnO material layer from being deposited in the region of the schottky contact metal window, and the ohmic contact metal window pattern is used to prevent a subsequently deposited second ZnO material layer from being deposited in the region of the ohmic contact metal window. After the second ZnO material layer is formed, the photoresist layer is removed to form the schottky contact metal window 106 and the ohmic contact metal window 105.
It is to be noted that, in order to electrically connect the ohmic contact electrode and the schottky contact metal with an external circuit, a metal interconnection line electrically connected to the schottky contact metal may be formed, and a metal interconnection line electrically connected to the ohmic contact electrode may be formed, and any suitable method known to those skilled in the art may be used for the formation of the metal interconnection line.
A passivation layer (not shown) may be optionally disposed on the surface of the second ZnO material layer 104 for protecting the device, wherein the material of the passivation layer may be any suitable insulating layer, such as an inorganic insulating layer of a silicon oxide layer, a silicon nitride layer, or a silicon oxynitride layer, an insulating layer including a layer of polyvinylphenol, polyimide, siloxane, or the like. In this embodiment, preferably, the material of the passivation layer includes silicon oxide.
The passivation layer may be formed using any suitable deposition method, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition.
It is worth mentioning that the method for forming the ohmic contact metal window and the schottky contact metal window can be used during the deposition of the passivation layer to retain the ohmic contact metal window and the schottky contact metal window.
The top view shape of the ohmic contact metal window may be any shape, such as a rectangle, a circle, a triangle, or other polygons.
In one example, as shown in the top view on the right side of fig. 3D, the schottky contact metal window 106 of the present invention further includes a schottky contact metal window 106, which penetrates through the second ZnO material layer 104 to expose a portion of the schottky contact metal 103 for electrical connection of the schottky contact metal with an external circuit, and when a passivation layer is disposed on the surface of the second ZnO material layer 104, the schottky contact metal window 106 also penetrates through the passivation layer.
The schottky contact metal window 106 may be located at any position, but it is necessary to ensure that a part of the schottky contact metal is exposed from the schottky contact metal window 106.
The description of the manufacturing method of the schottky ultraviolet detector of the present invention is completed so far, and the complete method may further include other intermediate steps or subsequent steps, which are not described in detail herein.
According to the Schottky ultraviolet detector formed by the manufacturing method, as the specific surface area of the Schottky contact metal 103 is increased, the specific surface area of the second ZnO material layer covering the Schottky contact metal 103 is correspondingly increased, and when the second ZnO material layer is irradiated by light, the area of the second ZnO material layer reached by the light is correspondingly increased, the absorption of the second ZnO material layer to the light and the collection efficiency of photon-generated carriers are increased, the photon-generated carrier concentration is improved, and the sensitivity of the Schottky ultraviolet detector is further improved.
The present invention has been illustrated by the above embodiments, but it should be understood that the above embodiments are for illustrative and descriptive purposes only and are not intended to limit the invention to the scope of the described embodiments. Furthermore, it will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that many variations and modifications may be made in accordance with the teachings of the present invention, which variations and modifications are within the scope of the present invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (18)
1. A schottky ultraviolet detector, comprising:
a substrate;
an ohmic contact electrode formed on a surface of the substrate;
a first ZnO material layer covering the substrate and the ohmic contact electrode;
the Schottky contact metal is formed on the surface of the first ZnO material layer, and comprises a bottom Schottky contact metal and a plurality of convex structures formed on the bottom Schottky contact metal; wherein the bottom Schottky contact metal covers a portion of the first ZnO material layer;
and the second ZnO material layer covers the Schottky contact metal and is in contact with the first ZnO material layer at the edge.
2. The schottky uv detector of claim 1 wherein the raised structures are arranged in an array; the shape of the convex structure is a strip shape or a column shape.
3. The schottky ultraviolet detector of claim 1 wherein the material of the first ZnO material layer comprises n-type ZnO or intrinsic ZnO; the material of the second ZnO material layer comprises n-type ZnO or intrinsic ZnO.
4. The schottky uv detector of claim 1, further comprising an ohmic contact metal window, wherein the ohmic contact metal window penetrates through the second ZnO material layer and the first ZnO material layer in sequence to expose a portion of the ohmic contact electrode, or the ohmic contact metal window penetrates through the substrate to expose a portion of the ohmic contact electrode, or the substrate is an ohmic contact metal plate for electrical connection with the ohmic contact electrode.
5. The schottky uv detector of claim 4 wherein the ohmic contact metal windows are disposed in corner regions of the substrate.
6. The schottky ultraviolet detector of claim 1, further comprising: and the Schottky contact metal window penetrates through the second ZnO material layer to expose part of the Schottky contact metal and is used for electrically connecting the Schottky contact metal with an external circuit.
7. The schottky uv detector of claim 1, wherein the second ZnO material layers on the sidewalls of adjacent raised structures have gaps or contact with each other.
8. A method of manufacturing a schottky uv detector, the method comprising:
providing a substrate, and forming an ohmic contact electrode on the surface of the substrate;
forming a first ZnO material layer to cover the substrate and the ohmic contact electrode;
forming Schottky contact metal on the surface of the first ZnO material layer, wherein the Schottky contact metal comprises bottom Schottky contact metal and a plurality of convex structures formed on the bottom Schottky contact metal; wherein the bottom Schottky contact metal covers a portion of the first ZnO material layer;
and forming a second ZnO material layer on the surface of the bottom Schottky contact metal and the surface of the protruding structure, wherein the second ZnO material layer is formed to be in contact with the first ZnO material layer at the edge.
9. The method of manufacturing of claim 8, wherein the step of forming the schottky contact metal comprises:
forming a Schottky contact metal material layer on the surface of the first ZnO material layer;
forming a patterned mask layer on the Schottky contact metal material layer, wherein the patterned mask layer is defined with a pattern of the projection structure which is formed in advance;
etching part of the Schottky contact metal material layer to stop in the Schottky contact metal material layer by taking the patterned mask layer as a mask so as to form the protruding structure, wherein the Schottky contact metal material layer below the protruding structure is used as the bottom Schottky contact metal;
and removing the patterned mask layer.
10. The method of manufacturing of claim 9, wherein after forming the schottky contact metal material layer, before forming the patterned mask, or after removing the patterned mask layer and before forming the second ZnO material layer, further comprising:
and etching and removing part of the edge of the Schottky metal material layer to expose part of the first ZnO material layer.
11. The method of manufacturing according to claim 8, wherein an ohmic contact metal window exposing a portion of the ohmic contact electrode is formed after the first ZnO material layer is formed, wherein,
the method for forming the ohmic contact metal window comprises the following steps:
coating a photoresist layer on the surface of the ohmic contact electrode;
patterning the photoresist layer through a photolithography process to form an ohmic contact metal window pattern;
and after the first ZnO material layer is formed, removing the photoresist layer to form the ohmic contact metal window, or after the second ZnO material layer is formed, removing the photoresist layer to form the ohmic contact metal window.
12. The manufacturing method according to claim 8, further comprising, after forming the ohmic contact electrode:
and forming an ohmic contact metal window in the surface of the substrate opposite to the ohmic contact electrode, wherein the ohmic contact metal window penetrates through the substrate to expose part of the ohmic contact electrode.
13. The method of manufacturing of claim 8, further comprising the step of forming a schottky contact metal window exposing a portion of said schottky contact metal after forming said second ZnO material layer, the method of forming said schottky contact metal window comprising:
forming a patterned mask layer on the surface of the second ZnO material layer, wherein the mask layer is defined with the shape of a Schottky contact metal window which is formed in advance;
etching the second ZnO material layer by taking the patterned mask layer as a mask until part of the surface of the Schottky contact metal is exposed so as to form a Schottky contact metal window;
and removing the patterned mask layer.
14. The method of manufacturing of claim 8, further comprising the step of forming a schottky contact metal window exposing a portion of said schottky contact metal after forming said second ZnO material layer, the method of forming said schottky contact metal window comprising:
forming a photoresist layer to cover one surface of the substrate, on which the Schottky contact metal is formed;
patterning the photoresist layer through a photoetching process to form a Schottky contact metal window shape;
after the second ZnO material layer is formed, the photoresist layer is removed to form the Schottky contact metal window.
15. The method of claim 8, wherein the raised structures are in the shape of bars or columns; the protruding structures are arranged in an array.
16. The manufacturing method according to claim 8, wherein a material of the first ZnO material layer includes n-type ZnO or intrinsic ZnO; the material of the second ZnO material layer comprises n-type ZnO or intrinsic ZnO.
17. The manufacturing method according to claim 8, wherein the substrate is an ohmic contact metal plate for electrical connection with the ohmic contact electrode.
18. The method according to claim 8, wherein the second ZnO material layers on the sidewalls of the adjacent protruding structures have a gap or contact therebetween.
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| CN112903755B (en) * | 2021-02-24 | 2023-06-02 | 太原理工大学 | Carbon dioxide sensor and preparation method thereof |
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| CN102142482B (en) * | 2011-01-10 | 2012-07-25 | 北京科技大学 | Method for preparing Schottky contact ZnO nano array ultraviolet detection device |
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