Gallium oxide heterojunction DUV sensor and method for manufacturing the same

Abstract

We provide a gallium oxide-based DUV sensor capable of detecting DUV. [Solution] The gallium oxide heterojunction DUV sensor comprises an n-type gallium oxide substrate, an n-type gallium oxide epitaxial layer epitaxially grown on the n-type gallium oxide substrate, a p-type nickel oxide layer formed on the n-type gallium oxide epitaxial layer and forming a pn heterojunction with the n-type gallium oxide epitaxial layer, a patterned upper electrode formed on the p-type nickel oxide layer, and a lower electrode formed on the lower surface of the n-type gallium oxide substrate.

Description

[Technical Field]

[0001] This invention relates to a heterojunction-based DUV (Deep UV) sensor. [Background technology]

[0002] UV sensors used in fire detectors include the UVtron series, which uses vacuum tubes, and the semiconductor photodiode series, which utilizes wide-bandgap (WBG) materials such as SiC and GaN. However, UV sensors currently in use do not possess the characteristics necessary for detecting arc fires.

[0003] Arc fire detectors are primarily used in locations that monitor electrical distribution panels and electrical equipment. While they have a short detection range, they require sensors capable of accurately detecting the arc wavelength range. Arcs are known to generate deep ultraviolet (DUV) light in the wavelength range of 200-280 nm. While WBG-type UV photosensors are more suitable for arc fire detectors than UVtrons, their low output current and noise issues, such as their reaction to UV-A and UV-B, make their application difficult. Furthermore, WBG-type UV photodiodes are approximately 20 times more expensive than conventional vacuum tube-type UVtrons, which also makes their application to fire detectors difficult. [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention aims to provide a gallium oxide-based DUV sensor capable of detecting DUV. [Means for solving the problem]

[0005] According to one aspect of the present invention, a gallium oxide heterojunction DUV sensor is provided, comprising: an n-type gallium oxide substrate; an n-type gallium oxide epitaxial layer epitaxially grown on the n-type gallium oxide substrate; a p-type nickel oxide layer formed on the n-type gallium oxide epitaxial layer and forming a pn heterojunction with the n-type gallium oxide epitaxial layer; a patterned upper electrode formed on the p-type nickel oxide layer; and a lower electrode formed on the lower surface of the n-type gallium oxide substrate.

[0006] In one embodiment, the patterned upper electrode may include a plurality of coaxial ring regions whose centers are located on the same axis, a linear region extending from the innermost coaxial ring region to the outermost coaxial ring region and connected to all of the plurality of coaxial ring regions, and a pad region connected to one end of the linear region that is furthest from the center.

[0007] As one embodiment, the patterned upper electrode may include a nickel-nichrome alloy layer formed on the p-type nickel oxide layer and forming ohmic contact with the p-type nickel oxide layer, and an aluminum-silicon alloy layer formed on the nickel-nichrome alloy layer.

[0008] As one embodiment, the patterned upper electrode may include a p-type contact resistance reducing layer formed on the p-type nickel oxide layer, a nickel-nichrome alloy layer formed on the p-type contact resistance reducing layer, and an aluminum-silicon alloy layer formed on the nickel-nichrome alloy layer.

[0009] As one embodiment, the p-type contact resistance reduction layer is a p+-type Li-doped nickel oxide layer, and the carrier concentration of the p+-type Li-doped nickel oxide layer may be higher than the carrier concentration of the p-type nickel oxide layer.

[0010] In one embodiment, the thickness of the p-type contact resistance reducing layer may be less than the thickness of the nickel-nichrome alloy layer.

[0011] As an example, the weight ratio (wt%) of aluminum and silicon in the aluminum-silicon alloy layer may be 99:1.

[0012] As an example, the lower electrode may include a titanium layer formed on the lower surface of the n-type gallium oxide substrate to form an ohmic contact, and an aluminum-silicon alloy layer formed on the titanium layer.

[0013] According to another aspect of the present invention, there is provided a method of manufacturing a DUV sensor of a gallium oxide heterojunction, including the steps of preparing an n-type gallium oxide substrate on which an n-type gallium oxide epitaxial layer is formed, forming a lower electrode on the lower surface of the n-type gallium oxide substrate, forming a p-type nickel oxide layer on the n-type gallium oxide epitaxial layer, and forming a patterned upper electrode on the p-type nickel oxide layer.

[0014] As an example, the step of forming a patterned upper electrode on the p-type nickel oxide layer may include forming an upper electrode pattern including a plurality of coaxial ring regions, a linear region connected to all of the plurality of coaxial ring regions, and a pad region connected to the linear region on the p-type nickel oxide layer, sputtering a nickel-chromium alloy target to form a nickel-chromium alloy layer on the p-type nickel oxide layer, sputtering an aluminum-silicon alloy target to form an aluminum-silicon alloy layer on the nickel-chromium alloy layer, and removing the upper electrode pattern.

[0015] As an example of an embodiment, the step of forming a patterned upper electrode on the p-type nickel oxide layer includes forming an upper electrode pattern on the p-type nickel oxide layer, the upper electrode pattern including a plurality of coaxial ring regions, a linear region connected to all of the plurality of coaxial ring regions, and a pad region connected to the linear region; sputtering a Li-doped nickel oxide target to form a p+-type Li-doped nickel oxide layer on the p-type nickel oxide layer; sputtering a nickel-chromium alloy target to form a nickel-chromium alloy layer on the p+-type Li-doped nickel oxide layer; sputtering an aluminum-silicon alloy target to form an aluminum-silicon alloy layer on the nickel-chromium alloy layer; and removing the upper electrode pattern.

Advantages of the Invention

[0016] According to the present invention, it is possible to improve the detection performance of a gallium oxide-based DUV sensor.

Brief Description of the Drawings

[0017] Hereinafter, the present invention will be described with reference to the embodiments shown in the accompanying drawings. For the sake of understanding, the same reference numerals are given to the same components throughout the accompanying drawings. The configurations shown in the accompanying drawings are merely exemplary embodiments implemented to explain the present invention, and the technical scope of the present invention is not limited thereto. In particular, the accompanying drawings are expressed with some components exaggerated for the sake of understanding the invention. It should be understood that the drawings are a means for facilitating the understanding of the invention, and the widths, thicknesses, etc. of the components shown in the drawings may be different in actual form. Also, throughout the detailed description of the invention, the same components are described using the same reference numerals. [Figure 1] FIG. is an exemplary diagram showing a DUV sensor of a gallium oxide heterojunction. [Figure 2] FIG. is an exemplary diagram showing a cross-section of an embodiment of a DUV sensor of a gallium oxide heterojunction along line AA' of FIG. 1. [Figure 3] Figure 2 shows the IV characteristic graph in the dark state of a gallium oxide heterojunction DUV sensor, as illustrated. [Figure 4] This figure illustrates a cross-section of another embodiment of a gallium oxide heterojunction DUV sensor along line AA' in Figure 1. [Figure 5] This diagram illustrates the manufacturing process of a gallium oxide heterojunction DUV sensor. [Figure 6] This diagram illustrates the manufacturing process of a gallium oxide heterojunction DUV sensor. [Figure 7] This diagram illustrates the manufacturing process of a gallium oxide heterojunction DUV sensor. [Figure 8a] Figure 4 shows the IV characteristic graph in the dark state of a gallium oxide heterojunction DUV sensor, as illustrated. [Figure 8b] Figure 4 shows the IV characteristic graph in the dark state of a gallium oxide heterojunction DUV sensor, as illustrated. [Figure 9a] This graph exemplifies the photocurrent at different UV wavelengths in a gallium oxide heterojunction DUV sensor. [Figure 9b] This graph exemplifies the photocurrent at different UV wavelengths in a gallium oxide heterojunction DUV sensor. [Figure 10] This graph shows the response of a gallium oxide heterojunction DUV sensor at different UV wavelengths. [Figure 11a] This graph exemplifies the photocurrent of a gallium oxide heterojunction DUV sensor at different temperatures. [Figure 11b] This graph exemplifies the photocurrent of a gallium oxide heterojunction DUV sensor at different temperatures. [Figure 12] This is an IV characteristic graph measured when a reverse voltage was applied to a gallium oxide heterojunction DUV sensor. [Figure 13] This is a graph showing the current characteristics of a gallium oxide heterojunction DUV sensor in response to the applied bias voltage. [Figure 14]This is a graph showing the photocurrent characteristics of a gallium oxide heterojunction DUV sensor as it is distanced from the light source. [Figure 15] This graph shows the photocurrent characteristics of a gallium oxide heterojunction DUV sensor at different irradiation wavelengths. [Modes for carrying out the invention]

[0018] The present invention is subject to various modifications and can have various embodiments; therefore, specific embodiments are illustrated in the drawings and described in detail therefrom. However, this does not mean that the present invention is limited to specific embodiments, but rather should be understood as encompassing all modifications, equivalents, and substitutions that fall within the spirit and technical scope of the present invention.

[0019] Terms such as "first," "second," etc., may be used to describe various components, but these components should not be limited by these terms. These terms are used solely for the purpose of distinguishing one component from another.

[0020] The terms used in this application are used to describe specific embodiments and are not intended to limit the invention. Singular expressions should be understood to encompass plural expressions unless the context clearly indicates otherwise. In this application, terms such as “includes” or “has” indicate the presence of features, numerical values, processes, operations, components, parts, or combinations thereof described in the specification, and should not be understood to preemptively exclude the possibility of the presence or addition of one or more other features, numerical values, processes, operations, components, parts, or combinations thereof.

[0021] When elements such as layers, regions, or substrates are described as existing "on" or extending "onto" other elements, those elements may exist directly on other elements or through intermediate elements. On the other hand, when an element is described as being "directly on" or extending "directly onto" another element, it means that there are no other intermediate elements. Also, when an element is described as being "connected" or "coupled" to another element, these elements may be directly connected or directly coupled, or through intermediate elements. On the other hand, when an element is described as being "directly connected" or "directly coupled," it means that there are no other intermediate elements.

[0022] Relative terms such as "below," "above," "upper," "lower," "horizontal," "lateral," and "vertical" may be used to describe the relationship between one element, layer, or region and another, as shown in the drawings. These terms should be understood as being intended to encompass not only the orientation shown in the drawings but also other orientations of the apparatus.

[0023] Embodiments of the present invention will be described in detail below with reference to the relevant drawings. The same components will be referred to by the same figure number throughout the description.

[0024] Figure 1 is an illustrative diagram of a gallium oxide heterojunction DUV sensor.

[0025] The gallium oxide heterojunction DUV sensor 10 detects DUV and generates an electric current. The upper surface of the gallium oxide heterojunction DUV sensor 10 is a light-receiving area to which light containing DUV is incident. The patterned upper electrode 140 can be formed on the p-NiO layer 130 (see Figures 2 and 4) so ​​as not to obstruct the incidence of DUV onto the p-NiO layer 130.

[0026] The patterned upper electrode 140 is formed by two or more layers stacked vertically and, together with the lower electrode 120 (see Figures 2 and 4), forms a current path that outputs the current generated by the DUV incident inside the sensor to the outside.

[0027] The patterned upper electrode 140 consists of multiple coaxial ring regions 140C1 to 140C5 whose centers are located on the same axis. The multiple coaxial ring regions 140C1 to 140C5 are connected by linear regions 140L1 and 140L2. The linear regions 140L1 and 140L2 extend from the innermost coaxial ring region 140C1 to the outermost coaxial ring region 140C5 and are connected to all of the multiple coaxial ring regions 140C1 to 140C5, but are not formed inside the innermost coaxial ring region 140C1. The pad region 140P is connected to one end of the linear regions 140L1 and 140L2 that is furthest from the center of the coaxial ring region.

[0028] The pad region 140P is formed as a x a quadrilateral region, where a is approximately 150 μm. Of the multiple coaxial ring regions 140C1 to 140C5, the innermost first coaxial ring region 140C1 has an inner diameter b of approximately 250 μm. Of the multiple coaxial ring regions 140C1 to 140C5, the distance c between two adjacent coaxial ring regions corresponds to half of the inner diameter b. On the other hand, the width d of the multiple coaxial ring regions 140C1 to 140C5 and the linear regions 140L1 and 140L2 is substantially the same, approximately 25 μm.

[0029] The gallium oxide heterojunction DUV sensor 10 is located within the sensor package 20 and is electrically connected to the output pins by wiring.

[0030] One end of the wire may be connected to the pad area 140P of the patterned upper electrode 140, and the other end may be connected to the output pin. The lower electrode 120 may be electrically fixed to the sensor package 20 by applying conductive paste.

[0031] Figure 2 is an illustrative diagram showing a cross-section of one embodiment of a gallium oxide heterojunction DUV sensor along the AA' line in Figure 1.

[0032] Referring to Figure 2, the gallium oxide heterojunction DUV sensor 10 may include an n-type gallium oxide substrate 100, an n-type gallium oxide epitaxial layer 110, a lower electrode 120, a p-type nickel oxide layer 130, and a patterned upper electrode 140.

[0033] For the manufacturing process of the gallium oxide heterojunction DUV sensor 10, please refer to Figures 5 to 7.

[0034] The n-type gallium oxide substrate 100 can be formed from gallium oxide (Ga2O3) doped with an n-type dopant, for example, β-Ga2O3. Examples of n-type dopants include tin (Sn) and silicon (Si), and the carrier concentration of the n-type gallium oxide substrate 100 is approximately 4.0 × 10⁻⁶. 18 cm -3 On the other hand, the thickness of the n-type gallium oxide substrate 100 is approximately 650 μm.

[0035] The n-type gallium oxide epitaxial layer 110 is a pathway through which the photocurrent generated by absorbing DUV light flows, and it forms a pn heterojunction with the p-type nickel oxide layer 130. The n-type gallium oxide epitaxial layer 110 can be formed by epitaxially growing a gallium oxide layer doped with an n-type dopant on an n-type gallium oxide substrate 100. Examples of n-type dopants include silicon (Si), and the carrier concentration of the n-type gallium oxide epitaxial layer 110 is approximately 1.0 × 10⁻⁶. 16 cm -3On the other hand, the thickness of the gallium oxide epitaxial layer 110 is approximately 5.0 μm. The n-type gallium oxide epitaxial layer 110 can be deposited by methods such as HVPE (Halide Vapor Phase Epitaxy), MOCVD (Metalorganic Chemical Vapor Deposition), Mist CVD, MBE (Molecular Beam Epitaxy), and PLD (Pulsed Laser Deposition).

[0036] The lower electrode 120 may consist of two or more metal layers sequentially stacked on the underside of the gallium oxide substrate 100. In the illustrated structure, the lower electrode 120 may include a titanium layer 120a deposited on the underside of the gallium oxide substrate 100 to a thickness of approximately 150 nm to form an ohmic contact, and an aluminum-silicon alloy layer 120b deposited on the titanium layer 120a to a thickness of approximately 400 nm. The aluminum-silicon alloy layer 120b is more resistant to oxidation than the aluminum layer and is attached to the sensor package 20 by soldering.

[0037] The p-type nickel oxide layer 130 can be formed by sputtering a gallium oxide target to a thickness of approximately 20 nm onto the n-type gallium oxide epitaxial layer 110 to form a pn heterojunction with the n-type gallium oxide epitaxial layer 110. The carrier concentration of the p-type nickel oxide layer 130 is approximately 1.0 × 10⁻⁶ 19 cm -3 That is the case.

[0038] The patterned upper electrode 140 consists of a plurality of coaxial ring regions 140C1 to 140C5, linear regions 140L1, 140L2, and pad region 140P, formed by two or more metal layers sequentially stacked on the p-type nickel oxide layer 130. In the illustrated structure, the patterned upper electrode 140 may include a nickel-nichrome alloy layer 140a deposited on the p-type nickel oxide layer 130 to a thickness of approximately 200 nm, and an aluminum-silicon alloy layer 140b deposited on the nickel-nichrome alloy layer 140a to a thickness of approximately 600 nm, in order to form ohmic contact with the p-type nickel oxide layer 130.

[0039] FIG. 3 is a graph of the I-V characteristics in the dark state of the DUV sensor of the gallium oxide heterojunction illustrated in FIG. 2.

[0040] From the I-V characteristic graph shown in a logarithmic scale measured by applying a voltage of about -6V to +6V to the DUV sensor 10 of the gallium oxide heterojunction in the dark, it is confirmed that the DUV sensor 10 of the gallium oxide heterojunction has the rectifying characteristics of a pn heterojunction diode.

[0041] FIG. 4 is a diagram exemplarily showing a cross-section of another embodiment of the DUV sensor of the gallium oxide heterojunction along the line AA' of FIG. 1.

[0042] Referring to FIG. 4, the DUV sensor 11 of the gallium oxide heterojunction may include an n-type gallium oxide substrate 100, an n-type gallium oxide epitaxial layer 110, a lower electrode 120, a p-type nickel oxide layer 130, and a patterned upper electrode 140.

[0043] The n-type gallium oxide substrate 100 may be formed of gallium oxide (Ga2O3) doped with an n-type dopant, for example, β-Ga2O3. The n-type dopant may be, for example, tin (Sn), silicon (Si), and the carrier concentration of the n-type gallium oxide substrate 100 may be about 4.0×10 18 cm -3 It can be. On the other hand, the thickness of the n-type gallium oxide substrate 100 may be about 650 μm.

[0044] The n-type gallium oxide epitaxial layer 110 is a path through which the photocurrent generated by absorbing DUV flows and forms a pn heterojunction with the p-type nickel oxide layer 130. The n-type gallium oxide epitaxial layer 110 may be formed by epitaxially growing a gallium oxide layer doped with an n-type dopant on the n-type gallium oxide substrate 100. The n-type dopant may be, for example, silicon (Si), and the carrier concentration of the n-type gallium oxide epitaxial layer 110 may be about 1.0×10 16 cm -3This is possible. On the other hand, the thickness of the n-type gallium oxide epitaxial layer 110 may be about 5.0 μm. The n-type gallium oxide epitaxial layer 110 can be deposited by methods such as HVPE (Halide Vapor Phase Epitaxy), MOCVD (Metalorganic Chemical Vapor Deposition), Mist CVD, MBE (Molecular Beam Epitaxy), and PLD (Pulsed Laser Deposition).

[0045] The lower electrode 120 may consist of two or more metal layers sequentially stacked on the underside of the gallium oxide substrate 100. In the illustrated structure, the lower electrode 120 may include a titanium layer 120a deposited on the underside of the gallium oxide substrate 100 to a thickness of approximately 150 nm to form an ohmic contact, and an aluminum-silicon alloy layer 120b deposited on the titanium layer 120a to a thickness of approximately 400 nm. The aluminum-silicon alloy layer 120b is more resistant to oxidation than the aluminum layer and is attached to the sensor package 20 by soldering.

[0046] The p-type nickel oxide layer 130 can be formed by sputtering a gallium oxide target to a thickness of approximately 20 nm onto the n-type gallium oxide epitaxial layer 110 so as to form a pn heterojunction with the n-type gallium oxide epitaxial layer 110. The carrier concentration of the p-type nickel oxide layer 130 is approximately 1.0 × 10⁻⁶. 19 cm -3 It is possible.

[0047] The patterned upper electrode 140 consists of a plurality of coaxial ring regions 140C1 to 140C5, linear regions 140L1 and 140L2, and a pad region 140P, which are formed from two or more metal layers sequentially stacked on the p-type nickel oxide layer 130. The patterned upper electrode 140 further includes a relatively high-concentration contact resistance reducing layer interposed between the p-type nickel oxide layer 130 and the nickel-nichrome alloy layer 140a to reduce contact resistance with the p-type nickel oxide layer 130. In the illustrated structure, the patterned upper electrode 140 may include a p+-type Li-doped nickel oxide layer 140c deposited on a p-type nickel oxide layer 130 to a thickness of about 150 nm, a nickel-nichrome alloy layer 140a deposited on the p+-type Li-doped nickel oxide layer 140c to a thickness of about 200 nm to form ohmic contact with the p+-type Li-doped nickel oxide layer 140c, and an aluminum-silicon alloy layer 140b deposited on the nickel-nichrome alloy layer 140a to a thickness of about 600 nm.

[0048] Figures 5 to 7 illustrate the manufacturing process of a gallium oxide heterojunction DUV sensor.

[0049] In step S1, an n-type gallium oxide substrate 100 on which an n-type gallium oxide epitaxial layer 110 is formed is prepared, and then it is washed to remove foreign matter.

[0050] The n-type gallium oxide substrate 100 and the n-type gallium oxide epitaxial layer 110 can be formed from β-Ga2O3 doped with an n-type dopant. The n-type gallium oxide epitaxial layer 110 can be formed on the n-type gallium oxide substrate 100 by epitaxial growth. The thickness of the n-type gallium oxide substrate 100 is approximately 650 μm, and the carrier concentration is approximately 4.0 × 10⁻⁶. 18 cm -3 This is possible. On the other hand, the thickness of the n-type gallium oxide epitaxial layer 110 is approximately 5.0 μm, and the carrier concentration is approximately 1.0 × 10⁻⁶. 16 cm -3 It is possible.

[0051] The n-type gallium oxide substrate 100 is sonicated for approximately 5 minutes while immersed in acetone to remove organic contaminants from its surface, and then sonicated for approximately 5 minutes while immersed in isopropyl alcohol (IPA) to remove residual organic contaminants and fine particles. Next, the n-type gallium oxide substrate 100 is washed with distilled water to remove any remaining chemicals. Then, the n-type gallium oxide substrate 100 is washed with BOE (Buffered Oxide Etchant) and then washed with distilled water to remove any remaining chemicals. Next, the n-type gallium oxide substrate 100 is irradiated with UVC for approximately 24 hours to remove any remaining organic contaminants and dry etch the thin oxide film formed on the n-type gallium oxide epitaxial layer 110.

[0052] In step S2, a lower electrode pattern PR1 is formed on the lower surface of the n-type gallium oxide substrate 100 to form the lower electrode 120. The lower electrode pattern PR1 defines grinding lines, and the lower electrode 120 can be formed in the remaining area excluding the grinding lines by the lower electrode pattern PR1. For example, the lower electrode pattern PR1 may be formed by spin-coating a liquid photoresist, followed by soft baking, exposure, and etching steps.

[0053] In step S3, two or more metal layers are sequentially deposited on the underside of the n-type gallium oxide substrate 100. The titanium layer 120a is formed on the underside of the n-type gallium oxide substrate 100 to a thickness of approximately 150 nm by DC sputtering a titanium target in an Ar gas atmosphere, and the aluminum-silicon alloy layer 120b can be formed on the underside of the n-type gallium oxide substrate 100 to a thickness of approximately 400 nm by DC sputtering an aluminum-silicon alloy target in an Ar gas atmosphere. The wt% of aluminum to silicon in the aluminum-silicon alloy target may be 99:1. During sputtering of the titanium layer 120a and the aluminum-silicon alloy layer 120b, the basic pressure is approximately 3 × 10⁻¹⁰ -6 The Torr, operating pressure is approximately 5 mTorr, Ar flow rate is approximately 20 sccm, and the temperature is room temperature.

[0054] In S4, the lower electrode pattern PR1 is removed to form the lower electrode 120. For example, the lower electrode pattern PR1 is lifted off to remove the metal layer deposited on the lower electrode pattern PR1 formed along the grinding line. After removing pattern PR1, UVC can be irradiated onto the n-type gallium oxide epitaxial layer 110 to remove any remaining contaminants.

[0055] In S5, a p-type nickel oxide layer 130 is formed on the n-type gallium oxide epitaxial layer 110. The p-type nickel oxide layer 130 can be formed on the n-type gallium oxide epitaxial layer 110 to a thickness of approximately 20 nm by RF sputtering of a nickel oxide target in an Ar-O2 mixed gas atmosphere. During sputtering of the p-type nickel oxide layer 130, the basic pressure is approximately 3 × 10⁻¹⁰ -6 Torr, operating pressure is approximately 5 mTorr, Ar flow rate is approximately 20 sccm, O2 flow rate is approximately 4 sccm, and the temperature is room temperature.

[0056] In S6, an upper electrode pattern PR2 is formed on the p-type nickel oxide layer 130 to form a patterned upper electrode 140. Pattern PR2 can be formed by spin-coating a liquid photoresist, followed by soft baking, exposure, and etching steps. Exposure and etching remove the photoresist in the regions where a plurality of coaxial ring regions 140C1 to 140C5, linear regions 140L1, 140L2, and pad region 140P are formed, exposing the p-type nickel oxide layer 130 in those regions.

[0057] In step S7, two or more metal layers are sequentially deposited on the p-type nickel oxide layer 130. When manufacturing the gallium oxide heterojunction DUV sensor 11 as illustrated in Figure 4, the p+-type Li-doped nickel oxide layer 140c can be formed on the p-type nickel oxide layer 130 to a thickness of approximately 150 nm by RF sputtering a Li-doped nickel oxide target in an Ar-O2 mixed gas atmosphere. During sputtering of the p+-type Li-doped nickel oxide layer 140c, the basic pressure is approximately 3 × 10⁻¹⁰ -6The Torr, operating pressure is approximately 5 mTorr, Ar flow rate is approximately 20 sccm, O2 flow rate is approximately 4 sccm, and the temperature is room temperature. The nickel-nichrome alloy layer 140a can be formed on the p+-type Li-doped nickel oxide layer 140c to a thickness of approximately 200 nm by DC sputtering a nickel-nichrome alloy target in an Ar gas atmosphere, and the aluminum-silicon alloy layer 140b can be formed on the nickel-nichrome alloy layer 140a to a thickness of approximately 600 nm by DC sputtering an aluminum-silicon alloy target in an Ar gas atmosphere. The wt% of nickel to chromium in the nickel-nichrome alloy target is 80:20, and the chromium increases the adhesion to the p+-type Li-doped nickel oxide layer 140c, which can reduce the phenomenon of electrode separation during post-processing, including wiring, and during use.

[0058] On the other hand, when manufacturing the gallium oxide heterojunction DUV sensor 10 illustrated in Figure 2, the step of generating the p+-type Li-doped nickel oxide layer 140c may be omitted. The nickel-nichrome alloy layer 140a may be formed on the p-type nickel oxide layer 130 to a thickness of approximately 200 nm by DC sputtering a nickel-nichrome alloy target in an Ar gas atmosphere, and the aluminum-silicon alloy layer 140b may be formed on the nickel-nichrome alloy layer 140a to a thickness of approximately 600 nm by DC sputtering an aluminum-silicon alloy target in an Ar gas atmosphere.

[0059] In S8, the upper electrode pattern PR2 is removed to form the upper electrode 140. For example, the upper electrode pattern PR2 is lifted off, and the metal layer deposited in the remaining region, excluding the multiple coaxial ring regions 140C1 to 140C5, the linear regions 140L1 and 140L2, and the pad region 140P, is removed.

[0060] Figures 8a and 8b are IV characteristic graphs in the dark state of the gallium oxide heterojunction DUV sensor exemplified in Figure 4.

[0061] Referring to both Figures 8a and 8b, the IV characteristic graphs, shown on a linear scale (Figure 8a) and a logarithmic scale (Figure 8b), show the photocurrent measured by applying a voltage of approximately -6V to 3V to the gallium oxide heterojunction DUV sensor 11 in the dark, confirming that it possesses the rectifying characteristics of a pn heterojunction diode. In particular, comparing Figure 8b with Figure 3, the slope of the IV characteristic curve increases significantly when a positive voltage is applied, confirming the effect of the contact resistance reduction layer. The hole concentration of the p+ type Li-doped nickel oxide layer 140c is approximately 1E20cm². -3 This material is deposited on a p-type nickel oxide layer 130 and ohmic-bonded to a nickel-nichrome alloy layer 140a, exhibiting lower contact resistance compared to existing P-NiO / NiCr. The low contact resistance generates a high photocurrent, which is advantageous for arc sensing. Furthermore, the multi-layer structure of the p-type nickel oxide layer / p+-type Li-doped nickel oxide layer improves leakage current and breakdown voltage characteristics against reverse voltage.

[0062] Figures 9a and 9b are illustrative graphs showing the photocurrent at different UV wavelengths in a gallium oxide heterojunction DUV sensor.

[0063] Figure 9a shows light with a wavelength of approximately 254 nm at approximately 1,000 μW / cm². 2 Figure 9b shows the photocurrent measured when a gallium oxide heterojunction-based DUV sensor was irradiated with light of approximately 222 nm wavelength at regular time intervals. The photocurrent when irradiated with DUV of approximately 254 nm wavelength (i.e., on-current) is approximately 5-7 × 10⁻¹⁰. -7 A is true, and when no light is irradiated (i.e., the photocurrent in the dark: off-current) is approximately 5-7 × 10⁻⁶. -11 A is the value, and the on / off ratio is approximately 7.1 × 10⁻⁶. 3 ~Approx. 1.4×10 4 On the other hand, the on-current when irradiating with DUV at a wavelength of approximately 222 nm is approximately 1.7 to 2.0 × 10⁻⁶. -6 A is the value, and the off-current when no light is irradiated is approximately 1.0 to 2.0 × 10⁻⁶. -10 A is the value, and the on / off ratio is approximately 8.5 × 103 ~Approx. 1.1×10 4 That is the case.

[0064] Figure 10 is a graph illustrating the response of a gallium oxide heterojunction DUV sensor to different UV wavelengths.

[0065] Referring to Figure 10, light with wavelengths of approximately 200 nm to 600 nm is emitted at approximately 1,000 μW / cm². 2 The responsiveness of a gallium oxide heterojunction DUV sensor with a 5V bias applied when irradiated at a certain intensity is shown. Here, the two gallium oxide heterojunction DUV sensors were fabricated to have p-type nickel oxide layers of approximately 20 nm and 50 nm thickness, respectively. When irradiated with light having wavelengths between approximately 250 nm and 350 nm, which partially belong to the DUV wavelength band, the gallium oxide heterojunction DUV sensors generate a photocurrent. In both gallium oxide heterojunction DUV sensors, a maximum peak was detected at a wavelength of approximately 260 nm. On the other hand, a second peak was detected at a wavelength of approximately 290 nm in the gallium oxide heterojunction DUV sensor with a p-type nickel oxide layer of approximately 20 nm thickness, while a second peak was detected at a wavelength of approximately 300 nm in the gallium oxide heterojunction DUV sensor with a p-type nickel oxide layer of approximately 50 nm thickness. Both p-type nickel oxide layers of approximately 20 nm and 50 nm thickness enable the gallium oxide heterojunction DUV sensor to exhibit excellent DUV responsiveness. However, it has been confirmed that as the thickness of the p-type nickel oxide layer decreases, the second peak is detected at a relatively shorter wavelength, resulting in even better DUV responsiveness.

[0066] Figures 11a and 11b are illustrative graphs showing the photocurrent of a gallium oxide heterojunction DUV sensor at different temperatures.

[0067] Figure 11a shows a gallium oxide heterojunction DUV sensor with a 5V bias applied, while varying the ambient temperature between approximately 30°C and 120°C, and measuring approximately 1,000 μW / cm². 2The photocurrent (including on-current and off-current) measured by irradiating with light at this intensity changes depending on the temperature, and although the on-current-off-current ratio changes because the magnitude of the photocurrent changes with temperature, it is confirmed that a distinguishable on-current-off-current ratio is maintained. On the other hand, as shown in Figure 11b, when the ambient temperature of a gallium oxide heterojunction DUV sensor with a 5V bias applied is increased to above approximately 130°C, the leakage current increases significantly, the on-current-off-current ratio decreases relatively significantly, and it is confirmed that the gallium oxide heterojunction DUV sensor operates abnormally.

[0068] Figure 12 shows the IV graph measured when a reverse voltage was applied to a gallium oxide heterojunction DUV sensor.

[0069] When a reverse voltage was applied to a gallium oxide heterojunction DUV sensor in the dark, the leakage current was measured and it was confirmed that the leakage current was approximately 1 nA or less, and the breakdown voltage was -200 V or higher.

[0070] Figure 13 shows the current graph due to the bias voltage applied to a gallium oxide heterojunction DUV sensor.

[0071] Referring to Figure 13, with a gallium oxide heterojunction DUV sensor subjected to 0V bias and 5V bias, a DUV light at approximately 254 nm wavelength was emitted at approximately 1,000 μW / cm². 2 The photocurrent was measured when irradiated at a constant time interval with a certain intensity. When irradiated with DUV at a wavelength of approximately 254 nm, the photocurrent (i.e., on-current) of the gallium oxide heterojunction DUV sensor in a 0V bias state was approximately 4.2 × 10⁻¹⁰. -7 At A, the on-current of a gallium oxide heterojunction DUV sensor under 5V bias is approximately 7.8 × 10⁻¹⁰ -7 A was measured. On the other hand, when no light was irradiated, a current close to 0A was measured. From this, it can be seen that when a positive voltage bias is applied to a gallium oxide heterojunction DUV sensor, the photocurrent increases and the on-current-off-current ratio also increases.

[0072] Figure 14 is a photocurrent graph showing the difference between the gallium oxide heterojunction DUV sensor and the light source due to the distance between them.

[0073] With a 5V bias applied to the gallium oxide heterojunction DUV sensor, the reading was approximately 1,000 μW / cm². 2 The photocurrent was measured while adjusting the distance from the light source irradiating with DUV light at approximately 254 nm wavelength at a given intensity. As expected, a decrease in photocurrent was observed as the distance from the light source increased.

[0074] Figure 15 shows the photocurrent graph of a gallium oxide heterojunction DUV sensor with respect to optical wavelength.

[0075] A gallium oxide heterojunction DUV sensor is placed in the sensor package 20, and with a 5V bias applied, light with wavelengths of approximately 254 nm and 400 nm is emitted at approximately 1,000 μW / cm². 2 The photocurrent of a gallium oxide heterojunction DUV sensor was measured by irradiating it with light at a constant intensity at regular time intervals. Comparing the photocurrent generated by DUV at approximately 254 nm with the photocurrent generated by UVA at a wavelength of 400 nm, it was confirmed that the DUV-to-UVA rejection ratio of the gallium oxide heterojunction DUV sensor was extremely high, at approximately 100 times.

[0076] The above description of the present invention is illustrative, and a person with ordinary skill in the art will understand that it can be easily modified into other specific forms without altering the technical idea or essential features of the present invention. Therefore, the embodiments described above should be understood to be illustrative and not limiting in all respects.

[0077] The scope of the present invention is indicated by the claims, which are set forth below rather than by the detailed description above, and all modifications or alterations derived from the meaning and scope of the claims, as well as the concept of equivalents thereof, should be interpreted as being included within the scope of the present invention.

Claims

1. n-type gallium oxide substrate and An n-type gallium oxide epitaxial layer grown on the n-type gallium oxide substrate, A p-type nickel oxide layer is formed on the n-type gallium oxide epitaxial layer and forms a pn heterojunction with the n-type gallium oxide epitaxial layer, A patterned upper electrode formed on the p-type nickel oxide layer, The lower electrode formed on the lower part of the n-type gallium oxide substrate, A gallium oxide heterojunction DUV sensor equipped with [the specified feature].

2. The patterned upper electrode is Multiple coaxial ring regions whose centers lie on the same axis, A linear region extending from the innermost coaxial ring region to the outermost coaxial ring region among the plurality of coaxial ring regions, and connected to all of the plurality of coaxial ring regions, A pad region connected to one of the ends of the aforementioned linear region, which is furthest from the center, A DUV sensor of a gallium oxide heterojunction according to claim 1, comprising:

3. The patterned upper electrode is A nickel-nichrome alloy layer is deposited on the p-type nickel oxide layer and forms ohmic contact with the p-type nickel oxide layer, An aluminum-silicon alloy layer deposited on the aforementioned nickel-nichrome alloy layer, A DUV sensor of a gallium oxide heterojunction according to claim 1, comprising:

4. The patterned upper electrode is A p-type contact resistance reducing layer deposited on the aforementioned p-type nickel oxide layer, A nickel-nichrome alloy layer deposited on the contact resistance reduction layer, An aluminum-silicon alloy layer deposited on the aforementioned nickel-nichrome alloy layer, A DUV sensor of a gallium oxide heterojunction according to claim 1, comprising:

5. The aforementioned p-type contact resistance reduction layer is a p+-type Li-doped nickel oxide layer. The carrier concentration in the p+-type Li-doped nickel oxide layer is higher than the carrier concentration in the p-type nickel oxide layer. The gallium oxide heterojunction DUV sensor according to claim 4.

6. The DUV sensor of a gallium oxide heterojunction according to claim 4, wherein the thickness of the p-type contact resistance reduction layer is smaller than the thickness of the nickel-nichrome alloy layer.

7. The gallium oxide heterojunction DUV sensor according to claim 3 or claim 4, wherein the weight ratio (wt%) of aluminum to silicon in the aluminum-silicon alloy layer is 99:

1.

8. The lower electrode is, A titanium layer deposited on the lower surface of the n-type gallium oxide substrate to form an ohmic contact, An aluminum-silicon alloy layer deposited on the titanium layer, A DUV sensor of a gallium oxide heterojunction according to claim 1, comprising:

9. The steps include: preparing an n-type gallium oxide substrate on which an n-type gallium oxide epitaxial layer is formed, The steps include forming a lower electrode on the lower surface of the n-type gallium oxide substrate, The steps include forming a p-type nickel oxide layer on the n-type gallium oxide epitaxial layer, The steps include forming a patterned upper electrode on the p-type nickel oxide layer, A method for manufacturing a gallium oxide heterojunction DUV sensor, including [the specified component].

10. The step of forming a patterned upper electrode on the p-type nickel oxide layer is, The steps include forming an upper electrode pattern on the p-type nickel oxide layer, which consists of a plurality of coaxial ring regions, a linear region connected to all of the plurality of coaxial ring regions, and a pad region connected to the linear region, The steps include: sputtering a nickel-nichrome alloy target to deposit a nickel-nichrome alloy layer onto the p-type nickel oxide layer; The steps include: sputtering an aluminum-silicon alloy target to deposit an aluminum-silicon alloy layer onto the nickel-nichrome alloy layer; The steps include removing the upper electrode pattern, A method for manufacturing a gallium oxide heterojunction DUV sensor according to claim 9, including the method described in claim 9.

11. The step of forming a patterned upper electrode on the p-type nickel oxide layer is, The steps include forming an upper electrode pattern on the p-type nickel oxide layer, which consists of a plurality of coaxial ring regions, a linear region connected to all of the plurality of coaxial ring regions, and a pad region connected to the linear region, The steps include: sputtering a Li-doped nickel oxide target to deposit a p+-type Li-doped nickel oxide layer onto the p-type nickel oxide layer; The steps include: sputtering a nickel-nichrome alloy target to deposit a nickel-nichrome alloy layer onto the p+-type Li-doped nickel oxide layer; The steps include: sputtering an aluminum-silicon alloy target to deposit an aluminum-silicon alloy layer onto the nickel-nichrome alloy layer; The steps include removing the upper electrode pattern, A method for manufacturing a gallium oxide heterojunction DUV sensor according to claim 9, including the method described in claim 9.

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