Gallium oxide infrared detector with enhanced pyroelectric effect and preparation method thereof
By fabricating Schottky junctions on specific crystal planes of gallium oxide thin films, the built-in electric field and intrinsic polarization electric field are aligned, solving the problem of the inability to superimpose pyroelectric responses in ε-phase gallium oxide materials and improving the pyroelectric performance of gallium oxide infrared detectors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUN YAT SEN UNIV
- Filing Date
- 2026-02-16
- Publication Date
- 2026-05-15
AI Technical Summary
In the prior art, the built-in electric field of the Schottky junction in ε-phase gallium oxide materials is opposite to the direction of the intrinsic polarization electric field, which prevents the pyroelectric response from being effectively superimposed, thus limiting the improvement of the pyroelectric performance of thin film materials.
By fabricating Schottky junctions on specific crystal planes of gallium oxide thin films, the direction of the built-in electric field is aligned with the direction of the intrinsic spontaneous polarization electric field. By combining the intrinsic pyroelectric effect of gallium oxide with the junction-type pyroelectric effect of the Schottky junction, signal superposition is achieved.
This significantly improves the pyroelectric response of the gallium oxide infrared detector, achieves the same-direction superposition of pyroelectric currents, and enhances the overall detection performance of the device.
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Figure CN122054909A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor device technology, and in particular to a gallium oxide infrared detector with enhanced pyroelectric effect and its fabrication method. Background Technology
[0002] Infrared detection technology has wide applications in military reconnaissance, security monitoring, industrial temperature measurement, and medical diagnosis. Among them, pyroelectric infrared detectors have become one of the important development directions of uncooled infrared detection due to their advantages such as no need for cooling, wide response spectrum, and low power consumption. The performance of pyroelectric materials is the core factor determining the sensitivity of the detector.
[0003] Traditional high-performance pyroelectric detectors primarily employ bulk materials such as lead zirconate titanate (PZT), lithium tantalate (LiTaO3), barium titanate (BaTiO3), and triglycine sulfate (TGS). While these materials possess high pyroelectric coefficients, their ceramic nature makes them difficult to integrate directly with silicon-based readout circuits in a monolithic manner, severely limiting the miniaturization of detector arrays. To meet the requirements for compatibility with complementary metal-oxide-semiconductor (CMOS) processes, research has shifted to wide-bandgap semiconductor thin-film materials such as aluminum nitride (AlN) and zinc oxide (ZnO). These materials are easily integrated on silicon substrates, but their inherent pyroelectric coefficients are typically 1-2 orders of magnitude lower than those of traditional bulk materials, limiting device detection performance. Therefore, effectively improving the pyroelectric characteristics of thin-film materials has become a key technological bottleneck that needs to be addressed.
[0004] To improve the pyroelectric properties of thin film materials, conventional technical approaches mainly include: external electric field polarization and elemental doping modification. The former forces the internal domains of the material to align in an oriented manner through a strong electric field, but the thin film is prone to dielectric breakdown, resulting in poor reliability. The latter has complex processes, low universality, and the effect is difficult to control precisely. In recent years, the pyroelectric effect based on Schottky junctions has provided a new approach to performance improvement. The Schottky junction formed by the contact between a semiconductor and a metal has a space charge region that is sensitive to temperature and can produce a significant charge response. If the intrinsic pyroelectric effect of the material can be coupled with the junction-type pyroelectric effect of the Schottky junction, theoretically, the response signal can be superimposed and enhanced. However, for polar semiconductor materials with a definite spontaneous polarization direction, achieving such coupling faces an inherent structural contradiction. Taking ε-phase gallium oxide as an example, its spontaneous polarization direction is determined by the crystal growth direction, usually fixed along the c-axis, i.e., from the <00-1> crystal plane to... <001> Crystal plane. The exposed surface of conventionally epitaxially grown ε-phase gallium oxide is the (001) crystal plane. When a Schottky junction is fabricated on this crystal plane, the direction of the built-in electric field of the formed Schottky junction is opposite to the direction of the intrinsic spontaneous polarization electric field of the material. This reverse electric field configuration causes the charge flow induced by intrinsic effects and junction effects to weaken each other in the external circuit when the temperature changes, failing to achieve synergistic enhancement of the effects and instead reducing the overall response. This contradiction limits the technical path for effectively enhancing the pyroelectric performance of such materials using Schottky junctions. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a pyroelectric-enhanced gallium oxide infrared detector and its fabrication method, which improves the pyroelectric response of ε-phase gallium oxide thin films in infrared detection applications. At the same time, it solves the technical problem that in ε-phase gallium oxide materials with fixed spontaneous polarization direction, the built-in electric field of the Schottky junction is opposite to the intrinsic polarization electric field, resulting in the inability to effectively superimpose the pyroelectric response.
[0006] In a first aspect, the present invention provides a gallium oxide infrared detector with enhanced pyroelectric effect, comprising, from bottom to top, a substrate, a first metal electrode layer, a gallium oxide thin film, and a second metal electrode layer; The gallium oxide thin film is in the ε-crystal phase. <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer and the gallium oxide thin film <001> Crystal planes form ohmic contacts; The second metal electrode layer forms a Schottky contact with the <00-1> crystal plane of the gallium oxide thin film.
[0007] Preferably, the material of the first metal electrode layer is titanium, aluminum, or molybdenum.
[0008] Preferably, the second metal electrode layer is platinum, palladium, gold, or nickel.
[0009] Preferably, the bonding surface of the substrate is made of metal, and the contact between the substrate and the first metal electrode layer is a metal-to-metal contact.
[0010] Preferably, the thickness of the first metal electrode layer is 10-30 nm; and the thickness of the second metal electrode layer is 80-120 nm.
[0011] Preferably, the thickness of the gallium oxide thin film is 700-900 nm.
[0012] Secondly, the present invention provides a method for fabricating a gallium oxide infrared detector with enhanced pyroelectric effect, comprising the following steps: S1) Growing on the substrate layer with <001> ε-phase gallium oxide thin film with crystal orientation; S2), in gallium oxide thin film <001> A first metal electrode layer is deposited on the crystal surface; S3) Bond the first metal electrode layer to the substrate; S4) Peel off the substrate layer to expose the <00-1> crystal plane of the ε-phase gallium oxide film; S5) A second metal electrode layer is deposited on the <00-1> crystal plane of the gallium oxide thin film.
[0013] Preferably, in step S1), the gallium oxide thin film has a doping concentration of 10. 16 ~10 18 cm -3 n-type semiconductor materials.
[0014] Preferably, after step S5), rapid thermal annealing is performed in a nitrogen atmosphere at 450-490°C to optimize the interface contact characteristics.
[0015] Preferably, the gallium oxide thin film is in the ε-crystal phase. <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer and the gallium oxide thin film <001> Crystal planes form ohmic contacts; The second metal electrode layer forms a Schottky contact with the <00-1> crystal plane of the gallium oxide thin film; The Schottky junction formed on the <00-1> crystal plane of the gallium oxide thin film has a built-in electric field direction pointing from the gallium oxide thin film to the second metal electrode layer; since the intrinsic spontaneous polarization electric field direction of the gallium oxide thin film is... <001> Since the crystal planes point to the <00-1> crystal planes, the built-in electric field direction of the Schottky junction is consistent with the direction of the intrinsic spontaneous polarization electric field.
[0016] The beneficial effects of this invention are as follows: 1. When the temperature of the device of the present invention changes due to infrared radiation, the intrinsic pyroelectric effect caused by the change in the spontaneous polarization intensity of gallium oxide and the junction pyroelectric effect caused by the temperature sensitivity of the space charge region of the Schottky junction are superimposed to generate pyroelectric currents in the same direction in the external circuit, thereby achieving signal superposition and significantly improving the overall pyroelectric response of the device. 2. This invention intentionally combines the intrinsic pyroelectric effect of gallium oxide with the junction-type pyroelectric effect of a metal-semiconductor Schottky junction in the device structure. Through key fabrication processes such as bonding and peeling, the Schottky junction is fabricated on a specific crystal plane of the gallium oxide thin film, so that the direction of its built-in electric field is consistent with the direction of the intrinsic spontaneous polarization electric field, realizing the superposition of the two physical effects in the same direction, improving the pyroelectric response of the ε-phase gallium oxide thin film in infrared detection applications, and solving the technical problem that in ε-phase gallium oxide materials with fixed spontaneous polarization direction, the built-in electric field of the Schottky junction is opposite to the direction of the intrinsic polarization electric field, resulting in the inability to effectively superimpose the pyroelectric response. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the detector structure according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram showing the direction of the spontaneous polarization electric field of the infrared detector in Embodiment 1 of the present invention and the direction of the built-in electric field of the Schottky junction; Figure 3 This is a test diagram of the pyroelectric coefficient of the infrared detector in Embodiment 1 of the present invention; Figure 4 This is the infrared response diagram of the infrared detector of Embodiment 1 of the present invention; Figure 5 The above are charge concentration analysis diagrams of the space charge region at the Schottky junction interface of the infrared detectors in Embodiments 1-4 of this invention. Figure 6 The above are pyroelectric coefficient analysis diagrams of the space charge region at the Schottky junction interface of the infrared detectors in Embodiments 1, 5, and 6 of the present invention. Figure 7 This is a test diagram of the pyroelectric coefficient of the infrared detector in Comparative Example 1 of the present invention; Figure 8 This is a test diagram of the pyroelectric coefficient of the infrared detector of Comparative Example 2 of the present invention.
[0018] In the figure, 101-substrate; 102-first metal electrode layer; 103-gallium oxide thin film; 104-second metal electrode layer. Detailed Implementation
[0019] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings: Example 1
[0020] like Figure 1As shown, this embodiment provides a pyroelectric effect-enhanced gallium oxide infrared detector, which includes, from bottom to top, a substrate 101, a first metal electrode layer 102, a gallium oxide thin film 103, and a second metal electrode layer 104. The gallium oxide thin film 103 is an ε-crystalline phase. <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer 102 and the gallium oxide thin film 103 <001> Crystal planes form ohmic contacts; The second metal electrode layer 104 forms a Schottky contact with the <00-1> crystal plane of the gallium oxide thin film 103.
[0021] In this embodiment, the gallium oxide thin film 103 has a thickness of 800 nm and a doping concentration of 1 × 10⁻⁶. 18 cm -3 ; The thickness of the first metal electrode layer 102 is 20 nm, and the material used is titanium (Ti). The second metal electrode layer 104 has a thickness of 100 nm and is made of platinum (Pt).
[0022] The method for fabricating the gallium oxide infrared detector in this embodiment is as follows: S1) An 800 nm thick layer with a doping concentration of 1 × 10⁻⁶ is epitaxially grown on the substrate using metal-organic chemical vapor deposition (MOCVD). 18 cm -3 The n-type ε-phase gallium oxide thin film 103 has the following growth direction: <001> Crystal orientation; S2), in the gallium oxide thin film 103 <001> On the crystal surface, a titanium Ti thin film with a thickness of 20 nm is deposited by electron beam evaporation to form the first metal electrode layer 102; S3) Using a bonding process, the gallium oxide thin film 103 with the first electrode layer is bonded to a substrate 101 with a metal layer on the surface with the Ti electrode facing down. S4) The temporary substrate is removed by a stripping process, thereby exposing the <00-1> crystal plane of the gallium oxide thin film 103; S5) On the exposed <00-1> crystal plane, a 100 nm thick platinum Pt film is deposited by electron beam evaporation to form the second metal electrode layer 104. S6) Rapid thermal annealing in a nitrogen atmosphere at 470°C optimizes interface contact characteristics, wherein the first metal electrode layer 102 and the gallium oxide thin film 103... <001> An ohmic contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103, and a Schottky contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103.
[0023] like Figure 2The diagram shows the spontaneous polarization electric field direction and the built-in electric field direction of the Schottky junction in the device fabricated in this embodiment. Analysis shows that the built-in electric field direction of the Schottky junction formed between the <00-1> crystal plane of the gallium oxide thin film 103 and the second metal electrode layer 104 points from the gallium oxide thin film 103 to the second metal electrode layer 104. The intrinsic spontaneous polarization electric field direction of the ε-phase gallium oxide thin film 103 is... <001> The crystal planes point to the <00-1> crystal planes. Therefore, the direction of the built-in electric field in the Schottky junction is consistent with the direction of the intrinsic spontaneous polarization electric field.
[0024] When the device is exposed to infrared radiation and its temperature rises, the intrinsic spontaneous polarization of the gallium oxide thin film 103 weakens, releasing free charges bound by spontaneous polarization. This generates a pyroelectric current in the external circuit, flowing from the first metal layer and substrate 101 to the second metal electrode layer 104. Simultaneously, the built-in potential of the Schottky junction decreases due to the increased temperature, reducing the charge in the space charge region, also generating a current in the same direction in the external circuit. The superposition of these two physical effects produces a significantly enhanced pyroelectric response current in the external circuit.
[0025] The device was placed in a pyroelectric coefficient testing system, and a thermocouple was used to measure the device from the substrate 101 side at 10 °C / min. -1 Heating was performed, and the pyroelectric current generated during the heating process was read using a 6514 electrometer. The test results are as follows: Figure 3 As shown, the pyroelectric coefficient is approximately 6.5 μC / m. -2 K -1 .
[0026] The fabricated detector underwent infrared response testing. The device was illuminated with a modulated infrared light source; at the instant the light source was turned on or off, the device generated a pyroelectric current due to the sudden temperature change. The test results are as follows: Figure 4 As shown, the device generated a stable pyroelectric current signal of approximately 30 pA, proving that the structure design can work effectively and has good infrared detection response characteristics. Example 2
[0027] like Figure 1 As shown, this embodiment provides a pyroelectric effect-enhanced gallium oxide infrared detector, which includes, from bottom to top, a substrate 101, a first metal electrode layer 102, a gallium oxide thin film 103, and a second metal electrode layer 104. The gallium oxide thin film 103 is an ε-crystalline phase. <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer 102 and the gallium oxide thin film 103 <001> Crystal planes form ohmic contacts; The second metal electrode layer 104 forms a Schottky contact with the <00-1> crystal plane of the gallium oxide thin film 103.
[0028] In this embodiment, the gallium oxide thin film 103 has a thickness of 800 nm and a doping concentration of 1 × 10⁻⁶. 18 cm -3 ; The thickness of the first metal electrode layer 102 is 20 nm, and the material used is titanium (Ti). The second metal electrode layer 104 has a thickness of 100 nm and is made of palladium (Pd).
[0029] The method for fabricating the gallium oxide infrared detector in this embodiment is as follows: S1) An 800 nm thick layer with a doping concentration of 1 × 10⁻⁶ is epitaxially grown on the substrate using metal-organic chemical vapor deposition (MOCVD). 18 cm -3 The n-type ε-phase gallium oxide thin film 103 has the following growth direction: <001> Crystal orientation; S2), in the gallium oxide thin film 103 <001> On the crystal surface, a titanium Ti thin film with a thickness of 20 nm is deposited by electron beam evaporation to form the first metal electrode layer 102; S3) Using a bonding process, the gallium oxide thin film 103 with the first electrode layer is bonded to a substrate 101 with a metal layer on the surface with the Ti electrode facing down. S4) The temporary substrate is removed by a stripping process, thereby exposing the <00-1> crystal plane of the gallium oxide thin film 103; S5) On the exposed <00-1> crystal plane, a 100nm thick palladium Pd film is deposited by electron beam evaporation to form a second metal electrode layer 104. S6) Rapid thermal annealing in a nitrogen atmosphere at 470°C optimizes interface contact characteristics, wherein the first metal electrode layer 102 and the gallium oxide thin film 103... <001> An ohmic contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103, and a Schottky contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103. Example 3
[0030] like Figure 1 As shown, this embodiment provides a pyroelectric effect-enhanced gallium oxide infrared detector, which includes, from bottom to top, a substrate 101, a first metal electrode layer 102, a gallium oxide thin film 103, and a second metal electrode layer 104. The gallium oxide thin film 103 is an ε-crystalline phase. <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer 102 and the gallium oxide thin film 103 <001> Crystal planes form ohmic contacts; The second metal electrode layer 104 forms a Schottky contact with the <00-1> crystal plane of the gallium oxide thin film 103.
[0031] In this embodiment, the gallium oxide thin film 103 has a thickness of 800 nm and a doping concentration of 1 × 10⁻⁶. 18 cm -3 ; The thickness of the first metal electrode layer 102 is 20 nm, and the material used is titanium (Ti). The second metal electrode layer 104 has a thickness of 100 nm and is made of gold (Au).
[0032] The method for fabricating the gallium oxide infrared detector in this embodiment is as follows: S1) An 800 nm thick layer with a doping concentration of 1 × 10⁻⁶ is epitaxially grown on the substrate using metal-organic chemical vapor deposition (MOCVD). 18 cm -3 The n-type ε-phase gallium oxide thin film 103 has the following growth direction: <001> Crystal orientation; S2), in the gallium oxide thin film 103 <001> On the crystal surface, a titanium Ti thin film with a thickness of 20 nm is deposited by electron beam evaporation to form the first metal electrode layer 102; S3) Using a bonding process, the gallium oxide thin film 103 with the first electrode layer is bonded to a substrate 101 with a metal layer on the surface with the Ti electrode facing down. S4) The temporary substrate is removed by a stripping process, thereby exposing the <00-1> crystal plane of the gallium oxide thin film 103; S5) On the exposed <00-1> crystal plane, a 100nm thick gold Au film is deposited by electron beam evaporation to form a second metal electrode layer 104. S6) Rapid thermal annealing in a nitrogen atmosphere at 470°C optimizes interface contact characteristics, wherein the first metal electrode layer 102 and the gallium oxide thin film 103... <001> An ohmic contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103, and a Schottky contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103. Example 4
[0033] like Figure 1 As shown, this embodiment provides a pyroelectric effect-enhanced gallium oxide infrared detector, which includes, from bottom to top, a substrate 101, a first metal electrode layer 102, a gallium oxide thin film 103, and a second metal electrode layer 104. The gallium oxide thin film 103 is an ε-crystalline phase. <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer 102 and the gallium oxide thin film 103 <001> Crystal planes form ohmic contacts; The second metal electrode layer 104 forms a Schottky contact with the <00-1> crystal plane of the gallium oxide thin film 103.
[0034] In this embodiment, the gallium oxide thin film 103 has a thickness of 800 nm and a doping concentration of 1 × 10⁻⁶. 18 cm -3 ; The thickness of the first metal electrode layer 102 is 20 nm, and the material used is titanium (Ti). The second metal electrode layer 104 has a thickness of 100 nm and is made of nickel (Ni).
[0035] The method for fabricating the gallium oxide infrared detector in this embodiment is as follows: S1) An 800 nm thick layer with a doping concentration of 1 × 10⁻⁶ is epitaxially grown on the substrate using metal-organic chemical vapor deposition (MOCVD). 18 cm -3 The n-type ε-phase gallium oxide thin film 103 has the following growth direction: <001> Crystal orientation; S2), in the gallium oxide thin film 103 <001> On the crystal surface, a titanium Ti thin film with a thickness of 20 nm is deposited by electron beam evaporation to form the first metal electrode layer 102; S3) Using a bonding process, the gallium oxide thin film 103 with the first electrode layer is bonded to a substrate 101 with a metal layer on the surface with the Ti electrode facing down. S4) The temporary substrate is removed by a stripping process, thereby exposing the <00-1> crystal plane of the gallium oxide thin film 103; S5) On the exposed <00-1> crystal plane, a 100nm thick nickel Ni film is deposited by electron beam evaporation to form the second metal electrode layer 104; S6) Rapid thermal annealing in a nitrogen atmosphere at 470°C optimizes interface contact characteristics, wherein the first metal electrode layer 102 and the gallium oxide thin film 103... <001> An ohmic contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103, and a Schottky contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103.
[0036] like Figure 5 As shown, theoretical analysis was performed on the devices prepared in Examples 1-4 to simulate the charge concentration in the space charge region at their Schottky junction interfaces. The analysis results indicate that the charge concentration in the space charge region of the Schottky junction formed between the gallium oxide thin film 103<00-1> crystal plane and nickel, gold, palladium, and platinum metals is greater than 4.5 × 10⁻⁶. 3 cm -3 The reliable Schottky contact means that the device will have a greater pyroelectric response under a unit temperature change. Example 5
[0037] like Figure 1As shown, this embodiment provides a pyroelectric effect-enhanced gallium oxide infrared detector, which includes, from bottom to top, a substrate 101, a first metal electrode layer 102, a gallium oxide thin film 103, and a second metal electrode layer 104. The gallium oxide thin film 103 is an ε-crystalline phase. <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer 102 and the gallium oxide thin film 103 <001> Crystal planes form ohmic contacts; The second metal electrode layer 104 forms a Schottky contact with the <00-1> crystal plane of the gallium oxide thin film 103.
[0038] In this embodiment, the gallium oxide thin film 103 has a thickness of 800 nm and a doping concentration of 1 × 10⁻⁶. 17 cm -3 ; The thickness of the first metal electrode layer 102 is 20 nm, and the material used is titanium (Ti). The second metal electrode layer 104 has a thickness of 100 nm and is made of platinum (Pt).
[0039] The method for fabricating the gallium oxide infrared detector in this embodiment is as follows: S1) An 800 nm thick layer with a doping concentration of 1 × 10⁻⁶ is epitaxially grown on the substrate using metal-organic chemical vapor deposition (MOCVD). 17 cm -3 The n-type ε-phase gallium oxide thin film 103 has the following growth direction: <001> Crystal orientation; S2), in the gallium oxide thin film 103 <001> On the crystal surface, a titanium Ti thin film with a thickness of 20 nm is deposited by electron beam evaporation to form the first metal electrode layer 102; S3) Using a bonding process, the gallium oxide thin film 103 with the first electrode layer is bonded to a substrate 101 with a metal layer on the surface with the Ti electrode facing down. S4) The temporary substrate is removed by a stripping process, thereby exposing the <00-1> crystal plane of the gallium oxide thin film 103; S5) On the exposed <00-1> crystal plane, a 100 nm thick platinum Pt film is deposited by electron beam evaporation to form the second metal electrode layer 104. S6) Rapid thermal annealing in a nitrogen atmosphere at 470°C optimizes interface contact characteristics, wherein the first metal electrode layer 102 and the gallium oxide thin film 103... <001> An ohmic contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103, and a Schottky contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103. Example 6
[0040] like Figure 1As shown, this embodiment provides a pyroelectric effect-enhanced gallium oxide infrared detector, which includes, from bottom to top, a substrate 101, a first metal electrode layer 102, a gallium oxide thin film 103, and a second metal electrode layer 104. The gallium oxide thin film 103 is an ε-crystalline phase. <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer 102 and the gallium oxide thin film 103 <001> Crystal planes form ohmic contacts; The second metal electrode layer 104 forms a Schottky contact with the <00-1> crystal plane of the gallium oxide thin film 103.
[0041] In this embodiment, the gallium oxide thin film 103 has a thickness of 800 nm and a doping concentration of 1 × 10⁻⁶. 16 cm -3 ; The thickness of the first metal electrode layer 102 is 20 nm, and the material used is titanium (Ti). The second metal electrode layer 104 has a thickness of 100 nm and is made of platinum (Pt).
[0042] The method for fabricating the gallium oxide infrared detector in this embodiment is as follows: S1) An 800 nm thick layer with a doping concentration of 1 × 10⁻⁶ is epitaxially grown on the substrate using metal-organic chemical vapor deposition (MOCVD). 16 cm -3 The n-type ε-phase gallium oxide thin film 103 has the following growth direction: <001> Crystal orientation; S2), in the gallium oxide thin film 103 <001> On the crystal surface, a titanium Ti thin film with a thickness of 20 nm is deposited by electron beam evaporation to form the first metal electrode layer 102; S3) Using a bonding process, the gallium oxide thin film 103 with the first electrode layer is bonded to a substrate 101 with a metal layer on the surface with the Ti electrode facing down. S4) The temporary substrate is removed by a stripping process, thereby exposing the <00-1> crystal plane of the gallium oxide thin film 103; S5) On the exposed <00-1> crystal plane, a 100 nm thick platinum Pt film is deposited by electron beam evaporation to form the second metal electrode layer 104. S6) Rapid thermal annealing in a nitrogen atmosphere at 470°C optimizes interface contact characteristics, wherein the first metal electrode layer 102 and the gallium oxide thin film 103... <001> An ohmic contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103, and a Schottky contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103.
[0043] like Figure 6As shown, theoretical analysis was performed on the devices prepared in Examples 1, 5, and 6 to simulate the pyroelectric coefficient of their Schottky junction interface. The analysis results show that at a doping concentration of 10... 16 cm -3 10 17 cm -3 10 18 cm -3 The pyroelectric coefficients of the gallium oxide thin film 103<00-1> crystal plane forming a Schottky junction with platinum metal are 0.16 μC / m. -2 K -1 0.34μC m -2 K -1 0.58μCm -2 K -1 This can effectively increase the pyroelectric response of the device. Comparative Example 1
[0044] like Figure 1 As shown, this embodiment provides a pyroelectric effect-enhanced gallium oxide infrared detector, which includes, from bottom to top, a substrate 101, a first metal electrode layer 102, a gallium oxide thin film 103, and a second metal electrode layer 104. The gallium oxide thin film 103 is an ε-crystalline phase. <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer 102 and the gallium oxide thin film 103 <001> Crystal planes form ohmic contacts; The second metal electrode layer 104 forms an ohmic contact with the <00-1> crystal plane of the gallium oxide thin film 103.
[0045] In this embodiment, the gallium oxide thin film 103 has a thickness of 800 nm and a doping concentration of 1 × 10⁻⁶. 18 cm -3 ; The thickness of the first metal electrode layer 102 and the second metal electrode layer 104 is 20 nm, and the material is titanium (Ti). The method for fabricating the gallium oxide infrared detector in this embodiment is as follows: S1) An 800 nm thick layer with a doping concentration of 1 × 10⁻⁶ is epitaxially grown on the substrate using metal-organic chemical vapor deposition (MOCVD). 18 cm -3 The n-type ε-phase gallium oxide thin film 103 has the following growth direction: <001> Crystal orientation; S2), in the gallium oxide thin film 103 <001> On the crystal surface, a titanium Ti thin film with a thickness of 20 nm is deposited by electron beam evaporation to form the first metal electrode layer 102; S3) Using a bonding process, the gallium oxide thin film 103 with the first electrode layer is bonded to a substrate 101 with a metal layer on the surface with the Ti electrode facing down. S4) The temporary substrate is removed by a stripping process, thereby exposing the <00-1> crystal plane of the gallium oxide thin film 103; S5) On the exposed <00-1> crystal plane, a titanium Ti film with a thickness of 20nm is deposited by electron beam evaporation to form the second metal electrode layer 104; S6) Rapid thermal annealing in a nitrogen atmosphere at 470°C optimizes interface contact characteristics, wherein the first metal electrode layer 102 and the gallium oxide thin film 103... <001> An ohmic contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103.
[0046] The device was placed in a pyroelectric coefficient testing system, and a thermocouple was used to measure the device from the substrate 101 side at 10 °C / min. -1 Heating was performed, and the pyroelectric current generated during the heating process was read using a 6514 electrometer. The test results are as follows: Figure 7 As shown, the pyroelectric coefficient is approximately 6.0 μC / m. -2 K -1 . Comparative Example 2
[0047] like Figure 1 As shown, this embodiment provides a pyroelectric effect-enhanced gallium oxide infrared detector, which includes, from bottom to top, a substrate 101, a first metal electrode layer 102, a gallium oxide thin film 103, and a second metal electrode layer 104. The gallium oxide thin film 103 is an ε-crystalline phase. <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer 102 and the gallium oxide thin film 103 <001> Schottky contacts are formed on the crystal planes; The second metal electrode layer 104 forms an ohmic contact with the <00-1> crystal plane of the gallium oxide thin film 103.
[0048] In this embodiment, the gallium oxide thin film 103 has a thickness of 800 nm and a doping concentration of 1 × 10⁻⁶. 18 cm -3 ; The thickness of the first metal electrode layer 102 is 100 nm, and the material used is platinum (Pt). The second metal electrode layer 104 has a thickness of 20 nm and is made of titanium (Ti).
[0049] The method for fabricating the gallium oxide infrared detector in this embodiment is as follows: S1) An 800 nm thick layer with a doping concentration of 1 × 10⁻⁶ is epitaxially grown on the substrate using metal-organic chemical vapor deposition (MOCVD). 18 cm -3 The n-type ε-phase gallium oxide thin film 103 has the following growth direction: <001> Crystal orientation; S2), in the gallium oxide thin film 103 <001> On the crystal surface, a 100nm thick platinum Pt thin film is deposited by electron beam evaporation to form the first metal electrode layer 102. S3) Using a bonding process, the gallium oxide thin film 103 with the first electrode layer is bonded to a substrate 101 with a metal layer on the surface with the Pt electrode facing down. S4) The temporary substrate is removed by a stripping process, thereby exposing the <00-1> crystal plane of the gallium oxide thin film 103; S5) On the exposed <00-1> crystal plane, a titanium Ti film with a thickness of 20nm is deposited by electron beam evaporation to form the second metal electrode layer 104; S6) Rapid thermal annealing in a nitrogen atmosphere at 470°C optimizes interface contact characteristics, wherein the first metal electrode layer 102 and the gallium oxide thin film 103... <001> A Schottky contact is formed on the surface, and an ohmic contact is formed between the second metal electrode layer 104 and the <00-1> surface of the gallium oxide thin film 103.
[0050] The device was placed in a pyroelectric coefficient testing system, and a thermocouple was used to measure the device from the substrate 101 side at 10 °C / min. -1 Heating was performed, and the pyroelectric current generated during the heating process was read using a 6514 electrometer. The test results are as follows: Figure 8 As shown, the pyroelectric coefficient is approximately 5.4 μC / m. -2 K -1 The pyroelectric coefficient of this device structure is lower than that of the device that forms ohmic contacts on both sides of the gallium oxide thin film 103, indicating that the built-in electric field of the Schottky junction, which is opposite to the direction of the intrinsic spontaneous polarization electric field of the gallium oxide thin film 103, weakens the overall pyroelectric effect.
[0051] The embodiments and descriptions above are merely illustrative of the principles and preferred embodiments of the present invention. Various changes and modifications may be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.
Claims
1. A gallium oxide infrared detector with enhanced pyroelectric effect, characterized in that, From bottom to top, it includes a substrate (101), a first metal electrode layer (102), a gallium oxide thin film (103), and a second metal electrode layer (104). The gallium oxide thin film (103) is an ε-crystalline phase. <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer (102) and the gallium oxide thin film (103) <001> Crystal planes form ohmic contacts; The second metal electrode layer (104) forms a Schottky contact with the <00-1> crystal plane of the gallium oxide thin film (103).
2. The pyroelectric-enhanced gallium oxide infrared detector according to claim 1, characterized in that: The material of the first metal electrode layer (102) is titanium, aluminum, or molybdenum.
3. A pyroelectric-enhanced gallium oxide infrared detector according to claim 1, characterized in that: The second metal electrode layer (104) is platinum, palladium, gold, or nickel.
4. A pyroelectric-enhanced gallium oxide infrared detector according to claim 1, characterized in that: The bonding surface of the substrate (101) is made of metal, and the contact between the substrate (101) and the first metal electrode layer (102) is a metal-to-metal contact.
5. A method for fabricating a gallium oxide infrared detector with enhanced pyroelectric effect, characterized in that, Includes the following steps: S1) Growing on the substrate layer with <001> ε-phase gallium oxide thin film with crystal orientation (103). S2), in the gallium oxide thin film (103) <001> A first metal electrode layer (102) is deposited on the crystal surface. S3) Bond the first metal electrode layer (102) to the substrate (101); S4) The substrate layer is peeled off to expose the <00-1> crystal plane of the ε-phase gallium oxide thin film (103); S5) A second metal electrode layer (104) is deposited on the <00-1> crystal plane of the gallium oxide thin film (103).
6. The method for fabricating a gallium oxide infrared detector with enhanced pyroelectric effect according to claim 5, characterized in that, In the step S1), the gallium oxide film (103) is an n-type semiconductor material with a doping concentration of 10 16 ~10 18 cm -3 -1.
7. The method for fabricating a pyroelectric-enhanced gallium oxide infrared detector according to claim 5, characterized in that, The gallium oxide thin film (103) is an ε-crystalline phase, and its <001> The crystal orientation is the spontaneous polarization direction; the first metal electrode layer (102) and the gallium oxide thin film (103) <001> Crystal planes form ohmic contacts; The second metal electrode layer (104) forms a Schottky contact with the <00-1> crystal plane of the gallium oxide thin film (103); The Schottky junction formed on the <00-1> crystal plane of the gallium oxide thin film (103) has a built-in electric field direction that points from the gallium oxide thin film (103) to the second metal electrode layer (104); since the intrinsic spontaneous polarization electric field direction of the gallium oxide thin film (103) is... <001> Since the crystal planes point to the <00-1> crystal planes, the built-in electric field direction of the Schottky junction is consistent with the direction of the intrinsic spontaneous polarization electric field.
8. The method for fabricating a pyroelectric-enhanced gallium oxide infrared detector according to claim 5, characterized in that, The thickness of the first metal electrode layer (102) is 10-30 nm; the thickness of the second metal electrode layer (104) is 80-120 nm.
9. A method for fabricating a gallium oxide infrared detector with enhanced pyroelectric effect according to claim 5, characterized in that, The thickness of the gallium oxide thin film (103) is 700-900 nm.
10. A method for fabricating a gallium oxide infrared detector with enhanced pyroelectric effect according to claim 5, characterized in that, After step S5), rapid thermal annealing is performed in a nitrogen atmosphere at 450-490°C to optimize the interface contact characteristics.