Broadband Ultraviolet Self-Powered Photodetector Constructed on Exfoliated β-Ga2O3/CuI Core-Shell Microwire Heterojunction with Superior Reliability

Photoelectrochemical properties of self-powered corundum-structured Ga2O3nanorod array/fluorine-doped SnO2photodetectors modulated by precursor concentrations

Herein, corundum-structured Ga2O3(α-Ga2O3) nanorod array/fluorine-doped SnO2(FTO) structures have been fabricated by hydrothermal and thermal annealing processes with different precursor concentrations from 0.01 to 0.06 M. The diameter and length of the nanorod arrays are much larger with increasing precursor concentrations due to more nucleation sites and precursor ions participating in the reaction procedures. The optical bandgap decreases from 4.75 to 4.47 eV because of the tensile stress relieving with increasing the precursor concentrations. Based on self-powered photoelectrochemical (PEC) photodetectors, the peak responsivity is improved from ∼0.33 mA W-1for 0.06 M to ∼1.51 mA W-1for 0.02 M. Schottky junctions can be formed in PEC cells. More photogenerated carriers can be produced in wider depletion region. From Mott-Schottky plots, the depletion regions become much wider with decreasing the precursor concentrations. Therefore, the enhance responsivity is owing to the wider depletion regions. Due to the reduced possibility of photogenerated holes captured by traps ascribed from fewer green and yellow luminescence defects, smaller charge transfer resistance, and shorter transportation route, the decay time becomes much faster through decreasing the precursor concentrations. Compared with the other self-poweredα-Ga2O3-nanorod-array-based PEC photodetectors, it shows the fastest response time (decay time of 0.005 s/0.026 s) simply modulated by precursor concentrations for the first time without employing complex precursors, seed layers or special device designs. Compared with other high-responsivity monoclinic Ga2O3(β-Ga2O3) self-powered photodetectors, our devices also show comparable response speed with simple control and design. This work provides the realization of fast-speed self-powered Ga2O3based solar-blind ultraviolet photodetectors by simple modulation processes and design, which is a significant guidance for their applications in warnings, imaging, computing, communication and logic circuit, in the future.

2 in. Bulk β-Ga2O3 Single Crystals Grown by EFG Method with High Wafer-Scale Quality

2 in. bulk β-Ga2O3 single crystals are successfully grown by the edge-defined film-fed growth method with a homemade furnace system. By considering the significance of wafer quality in future mass manufacture, a nine-point characterization method is developed to evaluate the full-scale quality of the processed 2 in. (100)-orientated β-Ga2O3 single-crystal wafers. Crystalline and structural characteristics were evaluated using X-ray diffraction and Raman spectroscopy, revealing decent crystalline quality with a mean full width at half-maximum value of 60.8 arcsec and homogeneous bonding structures. The statistical root-mean-square surface roughness, determined from nine scanning areas, was found to be only 0.196 nm, indicating superior surface quality. Linear optical properties and defect levels were further investigated using UV-visible spectrophotometry and photoluminescence spectroscopy. The high wafer-scale quality of the processed β-Ga2O3 wafers meets the requirements for homoepitaxial growth substrates in electronic and photonic devices with vertical configurations.

Enhancement of solar blind full band absorption in photodetector with Ga2O3 nanopore and Al nanograting

In this paper, we presented a novel double-layer light-trapping structure consisting of nanopores and nanograting positioned on both the surface and bottom of a gallium oxide-based solar-blind photodetector. Utilizing the finite element method (FEM), we thoroughly investigated the light absorption enhancement capabilities of this innovative design. The simulation results show that the double-layer nanostructure effectively combines the light absorption advantages of nanopores and nanogratings. Compared with thin film devices and devices with only nanopore or nanograting structures, double-layer nanostructured devices have a higher light absorption, achieving high light absorption in the solar blind area.

Deep-ultraviolet n-ZnGa2O4/p-GaN heterojunction photodetector fabricated by pulsed laser deposition

Zinc gallium oxide (ZnGa2O4) has attracted considerable interest in deep-ultraviolet photodetectors, due to the ultrawide bandgap, high transmittance in the ultraviolet (UV) region, and excellent environmental stability. In this study, ZnGa2O4 thin films were deposited on p-GaN epi-layers using pulsed laser deposition, resulting in improved crystalline quality. The ZnGa2O4 film exhibited a bandgap of 4.93 eV, calculated through absorption spectra. A heterojunction photodetector (PD) was constructed, demonstrating a rectification effect, an on/off ratio of 12,697 at -5.87 V, a peak responsivity of 14.5 mA/W, and a peak detectivity of 1.14 × 1012 Jones (262 nm, -6 V). The PD exhibited a fast response time (39 ms) and recovery time (30 ms) under 262 nm illumination. The band diagram based on the Anderson model elucidates the photoresponse and carrier transport mechanism. This work paves the way for advancing next-generation optoelectronics.

Self-powered deep ultraviolet photodetector based on p-CuI/n-ZnGa2O4 heterojunction with high sensitivity and fast speed

Self-powered deep ultraviolet photodetectors (DUV PDs) are essential in environmental monitoring, flame detection, missile guidance, aerospace, and other fields. A heterojunction photodetector based on p-CuI/n-ZnGa2O4 has been fabricated by pulsed laser deposition combined with vacuum thermal evaporation. Under 260 nm DUV light irradiation, the photodetector exhibits apparent self-powered performance with a maximum responsivity and specific detectivity of 2.75 mA/W and 1.10 × 1011 Jones at 0 V. The photodetector exhibits high repeatability and stability under 260 nm periodic illumination. The response and recovery time are 205 ms and 133 ms, respectively. This work provides an effective strategy for fabricating high-performance self-powered DUV photodetectors.

β-Ga2O3nanotube arrays for high-performance self-powered ultraviolet photoelectrochemical photodetectors

Self-powered ultraviolet (UV) photodetectors (PDs) are critical for future energy-efficient optoelectronic systems due to their low energy consumption and high sensitivity. In this paper, the vertically alignedβ-Ga2O3nanotube arrays (NTs) have been prepared on GaN/sapphire substrate by the thermal oxidation process combined with the dry etching technology, and applied in the UV photoelectrochemical photodetectors (PEC-PDs) for the first time. Based on the large specific surface area ofβ-Ga2O3NTs on GaN/sapphire substrates and the solid/liquid heterojunction, the PEC-PDs exhibit excellent self-powered characteristics under 255 nm (UVA) and 365 nm (UVC) light illumination. Under 255 nm (365 nm) light illumination, the maximum responsivity of 49.9 mA W-1(32.04 mA W-1) and a high detectivity of 1.58 × 1011Jones (1.01 × 1011Jones) were achieved for theβ-Ga2O3NTs photodetectors at 0 V bias. In addition, the device shows a fast rise/decay time of 8/4 ms (4/2 ms), which is superior to the level of the previously reported self-powered UV PEC-PDs. This high-performance PEC-PD has potential applications in next-generation low-energy UV detection systems.

Freestanding Crystalline β-Ga2O3 Flexible Membrane Obtained via Lattice Epitaxy Engineering for High-Performance Optoelectronic Device

Wearable and flexible β-Ga2O3-based semiconductor devices have attracted considerable attention, due to their outstanding performance and potential application in real-time optoelectronic monitoring and sensing. However, the unavailability of high-quality crystalline and flexible β-Ga2O3 membranes limits the fabrication of relevant devices. Here, through lattice epitaxy engineering together with the freestanding method, we demonstrate the preparation of a robust bending-resistant and crystalline β-Ga2O3 (-201) membrane. Based on this, we fabricate a flexible β-Ga2O3 photodetector device that shows comparable performance in photocurrent responsivity and spectral selectivity to conventional rigid β-Ga2O3 film-based devices. Moreover, based on the transferred β-Ga2O3 membrane on a silicon wafer, the PEDOT:PSS/β-Ga2O3 p-n heterojunction device with self-powered characteristic was constructed, further demonstrating its superior heterogeneous integration ability with other functional materials. Our results not only demonstrate the feasibility of obtaining a high-quality crystalline and flexible β-Ga2O3 membrane for an integrated device but also provide a pathway to realize flexible optical and electronic applications for other semiconducting materials.

High-Speed and Ultrasensitive Solar-Blind Ultraviolet Photodetectors Based on In Situ Grown β-Ga2O3 Single-Crystal Films

Deep-level defects in β-Ga2O3 that worsen the response speed and dark current (Id) of photodetectors (PDs) have been a long-standing issue for its application. Herein, an in situ grown single-crystal Ga2O3 nanoparticle seed layer (NPSL) was used to shorten the response time and reduce the Id of metal-semiconductor-metal (MSM) PDs. With the NPSL, the Id was reduced by 4 magnitudes from 0.389 μA to 81.03 pA, and the decay time (τd1/τd2) decreased from 258/1690 to 62/142 μs at -5 V. In addition, the PDs with the NPSL also exhibit a high responsivity (43.5 A W-1), high specific detectivity (2.81 × 1014 Jones), and large linear dynamic range (61 dB) under 254 nm illumination. The mechanism behind the performance improvement can be attributed to the suppression of the deep-level defects (i.e., self-trapped holes) and increase of the Schottky barrier. The barrier height extracted is increased by 0.18 eV compared with the case without the NPSL. Our work contributes to understanding the relationship between defects and the performance of PDs based on heteroepitaxial β-Ga2O3 thin films and provides an important reference for the development of high-speed and ultrasensitive deep ultraviolet PDs.

Solar-blind ultraviolet photodetector based on Nb2C/β-Ga2O3heterojunction

β-Ga2O3has been widely investigated for its stability and thermochemical properties. However, the preparation ofβ-Ga2O3thin films requires complex growth techniques and high growth temperatures, and this has hindered the application ofβ-Ga2O3thin films. In this study,β-Ga2O3thin films with good crystalline quality were prepared using a green method, and an ultraviolet (UV) detector based onβ-Ga2O3with a photocurrent of 2.54 × 10-6A and a dark current of 1.19 × 10-8A has been developed. Two-dimensional materials have become premium materials for applications in optoelectronic devices due to their high conductivity. Here, we use the suitable energy band structure between Nb2C and Ga2O3to create a high carrier migration barrier, which reduces the dark current of the device by an order of magnitude. In addition, the device exhibits solar-blind detection, high responsiveness (28 A W-1) and good stability. Thus, the Nb2C/β-Ga2O3heterojunction is expected to be one of the promising devices in the field of UV photoelectric detection.

Comprehensive Study on Ultra-Wide Band Gap La2O3/ε-Ga2O3 p-n Heterojunction Self-Powered Deep-UV Photodiodes for Flame Sensing

Solar-blind UV photodetectors have outstanding reliability and sensitivity in flame detection without interference from other signals and response quickly. Herein, we fabricated a solar-blind UV photodetector based on a La2O3/ε-Ga2O3 p-n heterojunction with a typical type-II band alignment. Benefiting from the photovoltaic effect formed by the space charge region across the junction interface, the photodetector exhibited a self-powered photocurrent of 1.4 nA at zero bias. Besides, this photodetector demonstrated excellent photo-to-dark current ratio of 2.68 × 104 under 254 nm UV light illumination and at a bias of 5 V, and a high specific detectivity of 2.31 × 1011 Jones and large responsivity of 1.67 mA/W were achieved. Importantly, the La2O3/ε-Ga2O3 heterojunction photodetector can rapidly respond to flames in milliseconds without any applied biases. Based on the performances described above, this novel La2O3/ε-Ga2O3 heterojunction is expected to be a candidate for future energy-efficient fire detection.

Enhanced Responsivity and Optoelectronic Properties of Self-Powered Solar-Blind Ag2O/β-Ga2O3 Heterojunction-Based Photodetector with Ag:AZO Co-Sputtered Electrode

A Ag:AZO electrode was used as an electrode for a self-powered solar-blind ultraviolet photodetector based on a Ag₂O/β-Ga₂O₃ heterojunction. The Ag:AZO electrode was fabricated by co-sputtering Ag and AZO heterogeneous targets using the structural characteristics of a Facing Targets Sputtering (FTS) system with two-facing targets, and the electrical, crystallographic, structural, and optical properties of the fabricated thin film were evaluated. A photodetector was fabricated and evaluated based on the research results that the surface roughness of the electrode can reduce the light energy loss by reducing the scattering and reflectance of incident light energy and improving the trapping phenomenon between interfaces. The thickness of the electrodes was varied from 20 nm to 50 nm depending on the sputtering time. The optoelectronic properties were measured under 254 nm UV-C light, the on/off ratio of the 20 nm Ag:AZO electrode with the lowest surface roughness was 2.01 × 10⁸, and the responsivity and detectivity were 56 mA/W and 6.99 × 10¹¹ Jones, respectively. The Ag₂O/β-Ga₂O₃-based solar-blind photodetector with a newly fabricated top electrode exhibited improved response with self-powered characteristics.

High Performance of Zero-Power-Consumption MOCVD-Grown β-Ga2O3-Based Solar-Blind Photodetectors with Ultralow Dark Current and High-Temperature Functionalities

In this article, we report on high-performance deep ultraviolet photodetectors (DUV PDs) fabricated on metal-organic chemical vapor deposition (MOCVD)-grown β-Ga₂O₃ heteroepitaxy that exhibit stable operation up to 125 °C. The fabricated DUV PDs exhibit self-powered behavior with an ultralow dark current of 1.75 fA and a very high photo-to-dark-current ratio (PDCR) of the order of 10⁵ at zero bias and >10⁵ at higher biases of 5 and 10 V, which remains almost constant up to 125 °C. The high responsivity of 6.62 A/W is obtained at 10 V at room temperature (RT) under the weak illumination of 42.86 μW/cm² of 260 nm wavelength. The detector shows very low noise equivalent power (NEP) of 5.74 × 10^-14 and 1.03 × 10^-16 W/Hz^1/2 and ultrahigh detectivity of 5.51 × 10¹¹ and 3.10 × 10¹⁴ Jones at 0 and 5 V, respectively, which shows its high detection sensitivity. The RT UV-visible (260:500 nm) rejection ratios of the order of 10³ at zero bias and 10⁵ at 5 V are obtained. These results demonstrate the potential of Ga₂O₃-based DUV PDs for solar-blind detection applications that require high-temperature robustness.

Solution-processed transparent p-type orthorhombic K doped SnO films and their application in a phototransistor

The exploitation of p-type oxide semiconductors with excellent optoelectrical properties as well as a simple preparation process is still challenging owing to the difficulty in producing hole carriers which results from strong hole localization in p-type oxide semiconductors. In this work, we succeeded in using ethylene glycol as a reductant to prepare orthorhombic structure SnO films using a sol-gel method and through K doping the optical and electrical properties of the films were improved. When the orthorhombic K doped SnO (K-SnO) films were applied in a phototransistor, it presented ultra-broadband photosensing from the ultraviolet to infrared region (300-1000 nm), demonstrating a photoresponsivity of 349 A W^-1 and a detectivity of 5.45 × 10¹² Jones at 900 nm under a light intensity of 0.00471 mW cm^-2. In particular, infrared photosensing was for the first time reported in the SnO based phototransistors. This work not only provides a simple method to fabricate high-performance and low-cost p-type K-SnO films and phototransistors, but may also suggest a new way to improve the p-type characteristics of other oxide semiconductors and devices.

Low-Temperature-Crystallized Ga2O3 Thin Films and Their TFT-Type Solar-Blind Photodetectors

Crystalline Ga₂O₃ (c-Ga₂O₃) is a promising candidate for next-generation solar-blind photodetectors (SBPDs) but is suffering from high processing temperatures. Herein, seed-induced engineering is proposed via adopting Zn as an induced metal for crystallizing Ga₂O₃, lowering the processing temperature by 200 °C. After annealing, the Zn/Ga₂O₃ consists of an inner Ga₂O₃ layer of a monoclinic crystalline phase, top ZnO crystals coming from Zn oxidation, and a thin corundum Ga₂O₃ layer between them, which implies a "seed-induced" crystallization mechanism besides the nonequilibrium chaotic state caused by the traditional electron transfer one. As a result, the tailored c-Ga₂O₃ thin-film transistor-type SBPD with enhanced packing density and finite oxygen deficiency demonstrates a satisfactory responsivity of 8.6 A/W and also an ultrahigh UVC/visible rejection ratio (R₂₅₄/R₄₅₀) of 2 × 10⁵. The seed-induced engineering forecasts its potential application in crystalline Ga₂O₃ SBPDs under a relatively low processing temperature.

Self-powered p-CuI/n-GaN heterojunction UV photodetector based on thermal evaporated high quality CuI thin film

With vacuum thermal evaporation, the CuI film was deposited on quartz and n-GaN substrates, and the morphology, crystalline structure and optical properties of the CuI films were investigated. According to the XRD results, the CuI film preferentially grew along [111] crystal orientation on the GaN epilayer. With Au and Ni/Au ohmic contact electrodes fabricated on CuI and n-GaN, a prototype p-CuI/n-GaN heterojunction UV photodetector strong UV spectral selectivity was created. At 0 V and 360 nm front illumination (0.32 mW/cm²), the heterojunction photodetector displayed outstanding self-powered detection performance with the responsivity (R), specific detectivity (D*), and on/off ratio up to 75.5 mA/W, 1.27×10¹² Jones, and ∼2320, respectively. Meanwhile, the p-CuI/n-GaN heterojunction photodetector had excellent atmosphere stability.

Ag2O/β-Ga2O3 Heterojunction-Based Self-Powered Solar Blind Photodetector with High Responsivity and Stability

Self-powered deep-ultraviolet photodetectors have received considerable attention in recent years because of their efficiency, reliability, and various applications in civilian and military fields. Herein, a Ag/Ag₂O layer is continuously deposited on a β-Ga₂O₃ epitaxial layer by a facing target sputtering system without opening the chamber, which has an advantage in time and cost. A p-n junction photodetector was constructed through the Ag₂O/β-Ga₂O₃ heterojunction and by varying the thickness of the Ag film, which was controlled by the sputtering time. The effect of top electrode thickness on the photoresponse characteristics of photodetectors was studied. Because thin Ag films have low surface roughness, indicating low optical loss and good interfacial conditions, photodetectors using a thin Ag film as the top electrode exhibit high photoresponsivity. However, Ag films that were thinner than the threshold thickness, which is the minimum thickness required to form a continuous, homogeneous surface film, exhibited rather low performance owing to the high reflection and scattering caused by the inhomogeneous surface morphology. The as-fabricated photodetector with a 20 nm Ag film presents a high on/off ratio of 3.43 × 10⁸, responsivity and detectivity of 25.65 mA/W and 6.10 × 10¹¹ Jones, respectively, and comparable rise and decay times of 108 and 80 ms, respectively. Additionally, even after three months of storage in an ambient environment, the photoresponse of the photodetector was maintained, indicating good stability in air. These results suggest that Ag₂O/β-Ga₂O₃ heterojunction-based photodetectors with thin Ag films can be used in various applications requiring deep-ultraviolet detection without an external power supply.

Flexible assembly of the PEDOT: PSS/ exfoliated β-Ga2O3 microwire hybrid heterojunction for high-performance self-powered solar-blind photodetector

Motivated by the goals of fabricating highly reliable, high performance, and cost-efficient self-powered photodetector (PD) for numerous scientific research and civil fields, an organic-inorganic hybrid solar-blind ultraviolet (UV) PD based on PEDOT: PSS/exfoliated β-Ga₂O₃ microwire heterojunction was fabricated by a flexible and cost-effective assembly method. Benefiting from the heterojunction constructed by the highly crystalline β-Ga₂O₃ and the excellent hole transport layer PEDOT: PSS, the device presents a high responsivity of 39.8 mA/W at 250 nm and a sharp cut-off edge at 280 nm without any power supply. Additionally, the ultra-high normalized photo-to-dark current ratio (> 10⁴ mW^-1cm²) under reverse bias and the superior detectivity of 2.4×10¹² Jones at zero bias demonstrate the excellent detection capabilities. Furthermore, the hybrid PD exhibits a rapid rise time (several milliseconds) and high rejection ratio (R₂₅₀/R₃₆₅: 5.8 × 10³), which further highlights its good spectral selectivity for solar-blind UV. The prominent performance is mainly ascribed to the efficient separation of the photogenerated carriers by the large built-in electric field of the advanced heterojunction. This flexible assembly strategy for solar-blind UV PD combines the advantages of high efficiency, low cost and high performance, providing more potential for PD investigation and application in the future.

Advances in Self-Powered Ultraviolet Photodetectors Based on P-N Heterojunction Low-Dimensional Nanostructures

Self-powered ultraviolet (UV) photodetectors have attracted considerable attention in recent years because of their vast applications in the military and civil fields. Among them, self-powered UV photodetectors based on p-n heterojunction low-dimensional nanostructures are a very attractive research field due to combining the advantages of low-dimensional semiconductor nanostructures (such as large specific surface area, excellent carrier transmission channel, and larger photoconductive gain) with the feature of working independently without an external power source. In this review, a selection of recent developments focused on improving the performance of self-powered UV photodetectors based on p-n heterojunction low-dimensional nanostructures from different aspects are summarized. It is expected that more novel, dexterous, and intelligent photodetectors will be developed as soon as possible on the basis of these works.

Pt/ZnGa2O4/p-Si Back-to-Back Heterojunction for Deep UV Sensitive Photovoltaic Photodetection with Ultralow Dark Current and High Spectral Selectivity

In this work, a strategy of constructing a back-to-back heterojunction is proposed to fabricate Si-based photovoltaic photodetectors with high deep ultraviolet (DUV) spectral selectivity. By combining Pt with a thickness of 4 nm with a ZnGa₂O₄/Si heterojunction, a back-to-back heterojunction is successfully constructed. Based on that, a Pt/ZnGa₂O₄/p-Si DUV photovoltaic detector with a low dark current density (∼9.6 × 10^-5 μA/cm²), a large photo-to-dark current ratio (PDCR, >10⁵), and a fast response speed (decay time <50 ms) is fabricated. At 0 V bias, this device displays a photoresponsivity of about 1.36 mA/W and a high deep ultraviolet-visible (DUV-vis) rejection ratio (R_258 nm/R_420 nm) of ∼1.1 × 10⁵, which are 1-2 orders of magnitude higher than those of most photovoltaic DUV detectors reported currently. Even at a working temperature of 470 K, the detectivity of this device can still reach ∼1.23 × 10¹⁰ Jones. In addition, compared with Au/ZnGa₂O₄/Si devices, the dark current and PDCR of this Pt/ZnGa₂O₄/Si device decrease by 2 orders of magnitude and increase by 1 order of magnitude, respectively. The enhanced performance of this ZnGa₂O₄/Si device can be attributed to the higher Schottky barrier established between Pt with a higher work function and ZnGa₂O₄. This strategy of adopting a back-to-back heterojunction device structure to hinder the visible light photoresponse of Si-based photodetectors and thus to reduce the dark current of a device can provide a reference for preparing photovoltaic DUV detectors with excellent performance.

A Spiro-MeOTAD/Ga2O3/Si p-i-n Junction Featuring Enhanced Self-Powered Solar-Blind Sensing via Balancing Absorption of Photons and Separation of Photogenerated Carriers

Solar blind ultraviolet (SBUV) self-powered photodetectors (PDs) have a great number of applications in civil and military exploration. Ga₂O₃ is a prospective candidate for SBUV detection owing to its reasonable bandgap corresponding to the SBUV waveband. Nevertheless, the previously reported Ga₂O₃ photovoltaic devices had low photoresponse performance and were still far from the demands of practical application. Herein, we propose an idea of using spiro-MeOTAD (spiro) as the SBUV transparent conductive layer to construct p-i-n PDs (p-spiro/Ga₂O₃/n-Si). With the aid of double built-in electric fields, the designed p-i-n PDs could operate without any external power source. Furtherly, the influence of spiro thickness on improving the photoelectric performance of devices is investigated in detail and the optimum device is achieved, translating to a peak responsivity of 192 mA/W upon a weak 254 nm light illumination of 2 μW/cm² at zero bias. In addition, the I-t curve of our PD shows binary response characteristics and a four-stage current response behavior under a small forward bias, and also, its underlying working mechanism is analyzed. In sum, this newly developed device presents great potential for booming the high energy-efficient optoelectronic devices in the short run.

Temperature-dependent device properties of γ-CuI and β-Ga2O3 heterojunctions

Abstract

Temperature-dependent studies of Ga2O3-based heterojunction devices are important in understanding its carrier transport mechanism, junction barrier potential, and stability at higher temperatures. In this study, we investigated the temperature-dependent device characteristics of the p-type γ-copper iodide (γ-CuI)/n-type β-gallium oxide (β‐Ga2O3) heterojunctions, thereby revealing their interface properties. The fabricated γ-CuI/β-Ga2O3 heterojunction showed excellent diode characteristics with a high rectification ratio and low reverse saturation current at 298 K in the presence of a large barrier height (0.632 eV). The temperature-dependent device characteristics were studied in the temperature range 273–473 K to investigate the heterojunction interface. With an increase in temperature, a gradual decrease in the ideality factor and an increase in the barrier height were observed, indicating barrier inhomogeneity at the heterojunction interface. Furthermore, the current–voltage measurement showed electrical hysteresis for the reverse saturation current, although it was not observed for the forward bias current. The presence of electrical hysteresis for the reverse saturation current and of the barrier inhomogeneity in the temperature-dependent characteristics indicates the presence of some level of interface states for the γ-CuI/β‐Ga2O3 heterojunction device. Thus, our study showed that the electrical hysteresis can be correlated with temperature-dependent electrical characteristics of the β‐Ga2O3-based heterojunction device, which signifies the presence of surface defects and interface states.

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