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Constructing nanoheterojunction is a crucial approach to achieving self-powered ultraviolet photodetectors based on Ga2O3. Two-dimensional modified NiS2 nanosheets are excellent candidates for fabricating nanoheterojunctions due to their high electrical conductivity for efficient charge transport, large surface area for enhanced light absorption, and exceptional chemical and thermal stability for reliable long-term UV detection. Herein, two-dimensional bimetallic (Co, Ni)-S2 nanosheets are proposed using a two-step hydrothermal synthesis method. Subsequently, a 3D/2D Ga2O3@(Co, Ni)-S2 heterojunction is constructed by depositing (Co, Ni)-S2 nanosheets onto the Ga2O3 nanowire network. Ga2O3@(Co, Ni)-S2 heterojunction photodetector achieves a self-driven responsivity of 36.56 mA W1– under 254 nm illumination, which is higher than the heterojunction photodetector based on Ga2O3 and monometallic NiS2 photodetector. Under 10 V bias, Ga2O3@(Co, Ni)-S2 heterojunction photodetector exhibits a high responsivity, detectivity, and external quantum efficiency of 1.51 A W1–, 7.68 × 1012 Jones, and 738.27%, which are 174.11, 8.95, and 174.11 times greater than those of pure Ga2O3 photodetector. The Ga2O3@(Co, Ni)-S2 photodetector also displays a faster response speed than that of the pure Ga2O3 photodetector. Calculated charge density differences show that improved performances are attributed to the advanced band alignment and interface charge transfer by forming the type I heterostructure between Ga2O3 and (Co, Ni)-S2. The established built-in electric field and lower Schottky barrier facilitate the effective transfer of photoelectrons at the nanointerface. Furthermore, the enhanced light absorption capacity and elevated conductivity of (Co, Ni)-S2 contribute to the improved photoelectric conversion capability. This research highlights that 2D bimetallic sulfide nanomaterials play a significant role in developing Ga2O3-based self-driven photodetectors. [ABSTRACT FROM AUTHOR]

Gallium oxide (Ga2O3) is an emerging and promising candidate for high-power and radiation-rich environments, such as space, thanks to its ultra-wide bandgap (~ 4.9 eV) and high critical electrical field (~ 8 MV/cm). Radiation in space, such as protons, alpha particles and heavy ions, can cause serious damage to electronic devices and even lead to permanent damage. However, assessing these devices' reliability and radiation hardness in space-like environments is often expensive and complex. In the present work, we utilize a technology computer-aided design (TCAD) simulation-based framework that uses the concept of non-ionizing energy loss (NIEL) to evaluate the displacement damage in electronic devices under particle irradiation. To assess the radiation tolerance of Ga2O3 diodes, first, a TCAD model for Ga2O3 Schottky barrier diodes (SBD) is developed and calibrated/benchmarked to an experimental device, followed by irradiation simulations. The results show that Ga2O3 SBD can withstand a 5 MeV proton fluence of ~ 1015 cm−2 with no change in the forward current voltage (IV) characteristics. This value is significantly higher than that of 4H-SiC (~5 × 1013 cm−2) and Si (~1 × 1012) SBDs with the same ideal breakdown voltage - VBR (1600 V), demonstrating the potential of Ga2O3 as a radiation-hard technology. [ABSTRACT FROM AUTHOR]

Plasmonic nanoarray structures offer great potential for high-performance photodetectors due to their excellent ability to effectively trap light. In this work, Ga2O3 solar-blind photodetectors with Ru nanogratings were designed, precisely fabricated, and characterized systematically for the first time. The Ru nanograting through localized surface plasmon resonance significantly concentrates the optical field, reduces the transmittance, and enhances light–matter interactions, ultimately increasing absorbance. Integrating the Ru nanograting into Ga2O3 films induces a blue shift in the response peak, from 245 nm in Ga2O3 films to 215 nm. Meanwhile, the peak current rises dramatically from 4.9 × 10–11 to 1.3 × 10–9 A. The peak responsivity and specific detectivity are increased by 4.9 × 102 times and 6.8 × 102 times, respectively. This modification also accelerates the response speed, with τr and τd, of 0.96/0.14 s, notably shorter than the 1.57/0.47 s in Ga2O3 films. The mechanisms underlying strengthened absorbance and light–matter interactions are comprehensively explained through both simulated and experimental data. This work lays the theoretical and experimental groundwork for future high-performance Ga2O3-based photodetectors. [ABSTRACT FROM AUTHOR]

This study explores the potential of 700‐nm‐thick heteroepitaxial α‐Ga2O3 thin films on c‐plane sapphire substrates for X‐ray detector applications. The crystal quality and optical bandgap of the heteroepitaxial α‐Ga2O3 thin films are comparable to those of high‐quality α‐Ga2O3 thin films. The α‐Ga2O3 thin film X‐ray detector with a metal–semiconductor–metal structure exhibits a charge neutral point shift, resulting in a short‐circuit current density of 9.07 nA cm−2 and an open‐circuit voltage of –1.2 V. The detector achieves the highest signal‐to‐noise ratio of 973 at 0 V, while the maximum sensitivity (14.7 μC Gyair−1 cm−2) occurs at 10 V. The proposed X‐ray detector demonstrates a reliable transient response and long‐term robustness, suggesting the promise of heteroepitaxial α‐Ga2O3 for low‐cost, high‐quality, large‐area X‐ray detectors. [ABSTRACT FROM AUTHOR]

Etching plays a key role in processing and manufacturing electronic and optoelectronic devices. For ultra-wide bandgap semiconductor gallium oxide (Ga2O3), its etching investigations and evolution mechanism are still at the earlier stage, and some more research gumption should be invested. In this review, we make a summary on the etching of Ga2O3, including dry (plasma) etching, wet chemical etching, and photoelectrochemical etching, and discuss the etching results, existing problems, and feasible solutions, in order to provide guidance and advises for furtherly developing the Ga2O3 etching and Ga2O3-based electronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]

The rapidly developing Artificial Intelligence era has an increasing demand for high‐performance organ‐on‐a‐chip systems, especially the vision system, which is the most essential perceptual system for human beings. However, traditional artificial vision systems require multiple functional components, which are not favorable for integration. Neuromorphic visual sensors (NVSs) inspired by the human retina combine visual sensing and multiple preprocessing functions. However, most NVSs require complex structures to achieve both photo sensing and memory, and are difficult to be large‐scale fabricated. Here, a novel In2O3‐Ga2O3 (InGaO) thin‐film‐based NVS with both high photosensitivity and superior photomemory performance is proposed, which can avoid the complex multilayer structure. The device possesses high accuracy optical communication and multiple retina‐like functions. Notably, this InGaO NVS achieves sensing of most UV light, and it has been experimentally confirmed to have excellent photoelectric synaptic performance under both 254 nm and 365 nm UV illumination. This work provides a feasible strategy to assist the human eye in sensing invisible UV light. [ABSTRACT FROM AUTHOR]

This study investigates the compositional analysis and growth of β-(InxGa1-x)2O3 thin films on (010) β-Ga2O3 substrates using mist chemical vapor deposition (CVD), including the effects of the growth temperature. We investigated the correlation between In composition and b-axis length in coherently grown films, vital for developing high-electron-mobility transistors and other devices based on β-(InxGa1-x)2O3. Analytical techniques, including X-ray diffraction (XRD), reciprocal space mapping, and atomic force microscopy, were employed to evaluate crystal structure, strain relaxation, and surface morphology. The study identified a linear relationship between In composition and b-axis length in coherently grown films, facilitating accurate composition determination from XRD peak positions. The films demonstrated high surface flatness with root-mean-square roughness below 0.6 nm, though minor relaxation and granular features emerged at higher In compositions (x = 0.083) at the growth temperature of 750°C. XRD results revealed that lattice relaxation were observed at a growth temperature of 700°C despite low In composition. In contrast, at 800°C, the In composition was higher than at 750°C, and coherent growth was achieved. The surface morphology was the flattest at 750°C. These findings indicate that the growth temperature plays a crucial role in the mist CVD growth of β-(InxGa1-x)2O3 thin films. This study offers insights into the relationship between In composition and lattice parameters in coherently grown β-(InxGa1-x)2O3 films, as well as the effect of growth conditions, contributing to the advancement of ultra-wide bandgap semiconductor device development. IMPACT STATEMENT: This paper presents innovative growth techniques for β-(InxGa1-x)₂O₃ thin films, enabling precise In composition control and enhancing potential applications in next-generation power-switching devices. [ABSTRACT FROM AUTHOR]

Gallium oxide (Ga2O3), zirconium oxide (ZrO2), and graphene oxide (GO) are prepared separately and then added to the Hibiscus. Then the mixture is added to polylactic acid (PLA) to expose it to the electrospinning process for obtaining beaded nanofibers. The beaded nanofibers are investigated using different techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDX), and thermogravimetric analysis (TGA). However, XRD showed that the crystal structure of Ga2O3 and ZrO2 is monoclinic. In addition, PLA has two main phases which are γ-PLA and β-PLA. This phase decreased upon increasing the additions. Further, SEM showed a decrease in the diameter of beaded nanofibers and reached 0.146 μm. Furthermore, TGA showed that the beaded nanofibers are stable until around 240 oC. Moreover, the cell viability showed that the composition is 97.2% at the concentration of 2.4 µg/mL. [ABSTRACT FROM AUTHOR]

This study presents the fabrication and characterization of a dual-functional Pt/Ga2O3/Pt optoelectronic synaptic device, capable of operating as both a memristor and a memcapacitor. We detail the optimized radio frequency (RF) sputtering parameters, including a base pressure of 8.7 × 10−7 Torr, RF power of 100 W, working pressure of 3 mTorr, and the use of high-purity Ga2O3 and Pt targets. These precisely controlled conditions facilitated the formation of an amorphous Ga2O3 thin film, as confirmed by XRD and AFM analyses, which demonstrated notable optical and electrical properties, including light absorption properties in the visible spectrum. The device demonstrated distinct resistive and capacitive switching behaviors, with memory characteristics highly dependent on the wavelength of the applied light. Ultraviolet (365 nm) exposure facilitated long-term memory retention, while visible light (660 nm) supported short-term memory behavior. Paired-pulse facilitation (PPF) measurements revealed that capacitance showed slower decay rates than EPSC, suggesting a more stable memory performance due to the dynamics of carrier trapping and detrapping at the insulator interface. Learning simulations further highlighted the efficiency of these devices, with improved memory retention upon repeated exposure to UV light pulses. Visual encoding simulations on a 3 × 3 pixel array also demonstrated effective multi-level memory storage using varying light intensities. These findings suggest that Ga2O3-based memristor and memcapacitor devices have significant potential for neuromorphic applications, offering tunable memory performance across various wavelengths from ultraviolet to red. [ABSTRACT FROM AUTHOR]

A charge trapping layer (CTL) technique is incorporated to achieve a normally-off Ga2O3 MOSFET. The gate dielectric was engineered using a stack composed of a blocking layer (16 nm ${\mathrm { HfO}}_{\mathrm { x}}$ / 2 nm Al2O3), a CTL (5.76 nm Al:HfO ${_{\text {x}}}~1$ :5), and a tunneling barrier (2 nm Al2O3 / 2 nm ${\mathrm { HfO}}_{\mathrm { x}}$ / 2 nm Al2O3). The trap profile of the CTL layer and the interface of the gate dielectric and Ga2O3 channel are studied by photon-stimulated characterization, which yield highly uniform results, indicating the high quality and uniformity of the proposed method. Furthermore, we conducted a time-dependent dielectric breakdown (TDDB) test on devices both without a field plate (NOFP) and with a source-connected field plate (SFP) to investigate the dielectric failure mechanism and gain valuable insights for the design of CTL-based Ga2O3 MOSFETs.

This study reports the effect of inductively coupled plasma reactive ion etching using a BCl3/Ar gas mixture on the sidewall taper angle (STA), etch rate, and surface morphology of (−201) β‐Ga2O3 substrates, as well as (−201)‐oriented β‐Ga2O3 films on sapphire, for nano‐fins of ≈200 nm width. Various etch parameters are systematically investigated for the β‐Ga2O3 films on sapphire, revealing that the STA is lower at high plasma density when chemical component increases, and the ion scattering decreases; achieving a STA of 1.5° ± 0.7°, accompanied by an etch rate of 114 nm min−1 and a reduction in surface roughness compared to before etching. Additionally, a strong positive correlation between the STA and the crystal orientation in the β‐Ga2O3 substrates is observed at lower plasma density, while a weak correlation is found between the STA and the crystal orientation at high plasma density. This study provides valuable insights for the fabrication of β‐Ga2O3 devices. [ABSTRACT FROM AUTHOR]

In this work, Cr3+ ion introduced germanate transparent glass-ceramics with one-step heat treatment around the glass transition temperature were prepared. By using TEM and other structural characterizations, it was demonstrated that the microstructure of glass-ceramics had uniform distribution and excellent grain development. Through XPS, FTIR, Raman and JMA model calculation, it was found that the substitution of Cr 2 O 3 for Ga 2 O 3 led to the decrease of [TO 4 ] ratio in the glass network, and the crystallization behavior changed to the whole crystallization. The results of optical performance tests indicated that the transmittance of the transparent glass-ceramics with one-step heat treatment was 46 % higher than that of glass-ceramics prepared by the two-step heat treatment, and the broadband emission intensity at 980 nm was 1.69 times higher than that of the basic glass. There is some guiding relevance to the innovative preparation approach suggested in this work for the creation of transparent glass-ceramics. [ABSTRACT FROM AUTHOR]

P‐type NiOx is employed for the fabrication of NiO/Ga2O3p–n diode. Addressing the challenge of low hole mobility in NiOx, an extensive investigation into the impact of oxygen stoichiometry engineering in NiOx is conducted. The meticulous optimization of the O2/Ar ratio to 30% during the sputtering process results in significant improvements, notably achieving enhanced hole mobility of 1.61 cm2 V−1 s. It leads to a low specific on‐resistance of 2.79 mΩ cm2 and a high rectification ratio of ≈1011, underscoring the efficacy of recombination transport mechanism driven by enhanced hole mobility. Detailed band alignment analysis between NiOx and Ga2O3 reveals a small band offset, with a valence band offset of 2.47 eV and a conduction band offset of 1.70 eV. It suggests a tailored modification of band alignment through the engineering the oxygen stoichiometry in NiOx, facilitating enhanced recombination conduction. The device exhibits a superior breakdown voltage (Vb) of 2780 V and a notable Baliga's figure of merit (BFOM) of 2.77 GW cm−2, surpassing the SiC unipolar figure of merit. The insights gained from this work are expected to inform future designs and optimizations of high‐performance Ga2O3 electronic devices. [ABSTRACT FROM AUTHOR]

Ga2O3 is a promising material for deep-ultraviolet (DUV) photodetectors due to its ultra-wide bandgap and high thermal and chemical stability. However, because of their relatively low responsivity, Ga2O3-based photodetectors still have difficulty meeting the requirements of practical applications. Here, we construct a high-performance Ga2O3 photodetector realized by back-illumination. Utilizing high-crystallinity epitaxially grown Ga2O3 as the DUV absorbing layer and the double-polished Al2O3 substrate as the transparent window for injection of photons, the device operating in the back-illuminated mode exhibits a higher DUV photoresponse and faster response speed than in the front-illuminated mode. Therefore, our experimental results have led to the development of a novel strategy for designing and fabricating high-performance Ga2O3 photodetectors. [ABSTRACT FROM AUTHOR]

This study is based on density functional theory, studied structure and electronic properties, optical properties, electrocatalytic water splitting to produce H 2 , and electrical properties of the WS 2 /Ga 2 O 3 heterojunction. By analyzing the photoelectric characteristics, we find that the WS 2 /Ga 2 O 3 heterojunction has built-in electric field, which can separate photogenerated carriers and effectively capture visible light for visible light photocatalysis. In addition, the change of Gibb free energy (Δ G) tends to 0, so when the WS 2 /Ga 2 O 3 heterojunction is used as a catalyst, the hydrogen evolution reaction tends to proceed spontaneously. Interestingly, by analyzing the electrical properties, we find that the large and obviously changed photogalvanic effect photocurrent is produced with the change of polarization angle and photon energy of the WS 2 /Ga 2 O 3 heterojunction, and it has the potential to become high-sensitivity optoelectronic detector. • The WS 2 /Ga 2 O 3 heterojunction has excellent electrocatalytic hydrogen production performance. • The WS 2 /Ga 2 O 3 heterojunction has obvious absorption peak in visible and infrared regions. • The PGE photocurrent of the WS 2 /Ga 2 O 3 heterojunction reaches 2.12 a 0 2/photon in the armchair direction. [ABSTRACT FROM AUTHOR]

Solar-blind ultraviolet (UV) photodetectors play a critical role in ultraviolet communication and monitoring, effectively reducing false alarm rates and improving the accuracy of detection systems across various settings, which has garnered significant attention. Due to its exceptional solar-blind photon absorption coefficient, extremely stable structure, and ultrawide bandgap (4.5–4.9 eV), Ga2O3 has recently been identified as a desirable material for solar-blind UV photodetectors. Heterojunctions can separate photogenerated electron–hole pairs and their absorption edges can be controlled by selecting semiconductors with appropriate bandgaps, making them an important technology for light detection. In this work, a self-powered solar-blind UV photodetector has been fabricated using a mechanically separated β-Ga2O3/Lu2O3 core–shell microwire heterostructure. Our device demonstrates excellent solar-blind UV discriminability with self-powered photodetection, the device exhibits a responsivity of 38.8 mA/W, a detectivity of 1.22 × 1012 Jones, a switching ratio of 1.43 × 103, and a decay rate under UV irradiation of 62 ms, benefiting from both photovoltaic and photoconductive effects. Due to the high dielectric constant of Lu2O3 thin films at the nanoscale, enables more effective modulation of internal electric fields within heterojunction structures, thereby enhancing the response speed and sensitivity of photodetectors. The application of self-powered photodetectors in solar-blind communication systems has achieved promising results, which provides a viable strategy for Ga2O3-based high-performance self-powered photodetectors. [ABSTRACT FROM AUTHOR]

Sensitive high‐energy photon detection from UV to X‐ray and high‐resolution array imaging are critical for medical diagnosis, space exploration, and scientific research. The key challenges for high‐performance photodetector and imaging arrays are the effective material and device design strategies for the miniaturization and integration of the device. Here, photon‐controlled diodes (i.e., the detector has rectifying characteristics only under light irradiation) are proposed for high‐resolution and anti‐crosstalk array imaging applications without integrating the switching element. Based on ultra‐wide bandgap semiconductor Ga2O3, the sensitive DUV/X‐ray photon‐controlled diodes are realized by the design of high‐resistance Ga2O3 film and high‐barrier contact. The device exhibits remarkable detection performance, including high photo‐responsivity (168 A W−1) and specific detectivity (1.45 × 1015 Jones) under DUV illumination, as well as a high sensitivity (1.23 × 105 µC Gyair−1 cm−2) under X‐ray light. Moreover, the low dark current and excellent rectification characteristics are obtained. Furthermore, its potential for high‐density and anti‐crosstalk array imaging applications is verified. These results not only bring forth new insights in the implementation of high‐performance DUV/X‐ray photodetector, but also pave a feasible way to realize high pixel density detector array through the simplified fabrication process for high‐resolution imaging applications. [ABSTRACT FROM AUTHOR]

The impact of Fröhlich scattering on β‐Ga2O3 Schottky barrier diodes (SBDs) electron mobility, particularly at high temperatures, is investigated. This scattering is crucial due to electron–polar optical phonon interactions. Temperature‐dependent I–V characteristics of a β‐Ga2O3 SBD from 300 to 473 K showed significant current reduction due to electron–polar optical phonon scattering, supported by correlation with mobility profiles. Additionally, in situ temperature‐dependent XPS analysis revealed a notable positive shift in core‐level binding energy, attributed to heightened electron–phonon interactions. This study provides crucial insights into carrier transport mechanisms, essential for power device design and operation. [ABSTRACT FROM AUTHOR]

In this study, we successfully synthesized three gallium oxide thin films on (0001)-faceted Al 2 O 3 substrates using hydrogen-reduced chemical vapor deposition (CVD) at different deposition temperatures, resulting in distinct morphologies and crystalline phases. These films consist of two pure-phase β-Ga 2 O 3 films and one mixed-phase film comprising both β- and ε-Ga 2 O 3 phases. The mixed-phase samples were subsequently annealed at high temperatures to obtain pure-phase β-Ga 2 O 3 thin films. Furthermore, by precisely controlling the growth temperature, we achieved in-situ formation of Ga 2 O 3 nanostructures (nanowires and nanoribbons) on the surface of the β-Ga 2 O 3 thin films. The presence of different dominant crystal planes in the samples was confirmed through X-ray diffraction analysis (XRD) for verification purposes. In directly grown β-Ga 2 O 3 films, the (−201) plane emerged as the primary crystallographic plane, while both the (−201) and (401) planes dominated in β-Ga 2 O 3 films obtained via ε-Ga 2 O 3 film annealing. Raman spectroscopy findings further supported these observations regarding the crystalline phase of the films as observed through XRD analysis. Scanning electron microscopy (SEM) images revealed distinct film morphologies resulting from variations in deposition temperatures. A flatter surface was observed when a higher proportion of ε-Ga 2 O 3 was present in the film, however, regular cracking occurred after annealing. Atomic Force Microscope (AFM) images demonstrated that at a deposition temperature of 800 °C, regular steps were present on the film's surface. Mixed-phase films exhibited hillock morphology that disappeared after annealing, leading to a decrease in the surface roughness in root mean square (RMS) value. By elevating the growth temperature, a significantly enhanced density of gallium oxide nanoribbons can be seamlessly integrated onto the film surface. The transferred nanoribbons exhibit an ultra-thin profile with a minimum thickness of merely 12 nm, rendering them more slender and economically advantageous in comparison to conventional mechanical stripping methods. This study presents a CVD-based approach for growing gallium oxide thin films with varying morphologies by employing temperature modulation and demonstrates an innovative one-step method for growing nanostructures on gallium oxide films in situ, providing valuable insights for future device development involving gallium oxide. [ABSTRACT FROM AUTHOR]

Due to their ultra-wide bandgap and brilliant chemical stability, gallium oxide (Ga2O3) is considered one of the most promising materials for solar-blind photodetectors. However, the preparation of high-performance solar-blind photodetectors based on a low-cost Ga2O3 thin film still remains a great challenge. In this work, β-Ga2O3 thin films with nanoscale thickness have been prepared on a sapphire substrate by a facile and effective sol–gel spin-coating method. At the same time, the effect of local surface plasmon resonance (LSPR) is introduced by fabrication of Pt nanoparticles (NPs) in order to improve the optoelectronic performance of photodetectors based on polycrystalline Ga2O3. By adding Pt NPs, significant performance enhancement has been observed in terms of on/off ratio, responsiveness, detectivity, and external quantum efficiency by 618.7%, 66.7%, 390.7%, and 266.7%, respectively, reaching a comparable level to certain single-crystalline devices. [ABSTRACT FROM AUTHOR]

As devices become more miniaturized and integrated, the heat flux density has increased, highlighting the issue of heat concentration, especially for low thermal conductivity gallium oxide (Ga2O3). This study utilizes diamond composite substrates with an AlN transition layer to assist Ga2O3 in rapid thermal dissipation. All samples were prepared using pulsed laser deposition (PLD) and annealed at 600–1000 °C. The microstructure, surface morphology, vacancy defects, and thermal characteristics of post-annealed Ga2O3 were then thoroughly investigated to determine the mechanism by which annealing temperature influences the heat transfer of heterostructures. The results demonstrate that increasing the annealing temperature can improve the crystallinity of Ga2O3 while also reducing oxygen vacancy defects from 20.6% to 9.9%. As the temperature rises to 1000 °C, the thermal conductivity of Ga2O3 reaches a maximum of 12.25 W/(m·K). However, the interface microstructure has no direct correlation with annealing temperature. At 700 °C, Ga2O3/diamond exhibits a maximum thermal boundary conductance of 127.06 MW/(m2·K). Higher temperatures (>800 °C) cause irregular mixtures to form near the heterointerface, intensifying phonon interface scattering and sharply deteriorating interfacial heat transfer. These findings contribute to a better understanding of the heterointerface thermal transfer influence mechanism and provide theoretical guidance for the thermal management design and physical analysis of Ga2O3-based power devices. [ABSTRACT FROM AUTHOR]

Abstract Photodetectors play a crucial role in converting light signals into electrical signals and have significant applications in various fields such as communications, imaging, and sensing. However, the fabrication of a photodetector is a complex process that involves precise control of surface preparation, lithography, and deposition techniques. Here the study demonstrates that GaN/Ga2O3 heterojunctions can be fabricated utilizing laser processing to transform the surface of GaN into Ga2O3. The GaN/Ga2O3 heterojunctions exhibit good reproducibility, uniformity, and ability to operate under zero bias, with a responsivity of 110.22 mA W−1, a detection rate of 5.56 × 1011 jones, and an external quantum efficiency of 42.34%. Moreover, an 8 × 8 photodetector array based on GaN/Ga2O3 heterojunction is fabricated via laser writing and is demonstrated to have ultraviolet imaging capabilities. This report presents the pioneering fabrication of a photodetector array using laser writing. The findings offer a versatile and scalable approach for the production of large‐area heterojunction photodetector arrays.

Abstract The structural and electrical properties of undoped and Sn doped κ‐Ga2O3 layers grown by epitaxial lateral overgrowth on TiO2/sapphire substrates using stripe and point masks show that the crystalline structure of the films can be greatly improved relative to conventional planar growth. The undoped films are semi‐insulating, with the Fermi level pinned near EC‐0.7 eV, and deep electron traps at EC‐0.5 eV and EC‐0.3 eV are detectable in thermally stimulated current and photoinduced current transient spectra measurements. Low concentration Sn doping results in net donor concentrations of ≈ 1013 cm−3, and deep trap spectra determined by electron traps at EC‐0.5 eV, and deep acceptors with an optical ionization threshold near 2 and 3.1 eV. Treatment of the samples in hydrogen plasma at 330 °C increases the donor density near the surface to ≈ 1019 cm−3. Such samples show strong persistent photocapacitance and photoconductivity, indicating the possible DX‐like character of the centers involved. For thin (5 µm) κ‐Ga2O3 films grown on GaN/sapphire templates, p‐type‐like behavior is unexpectedly observed in electrical properties and we discuss the possible formation of a 2D hole gas at the κ‐Ga2O3/GaN interface.

Abstract Gallium oxide (Ga2O3) is an emerging ultra‐wide bandgap (UWBG) semiconductor material that has gained significant attention in the field of high voltage and high frequency power electronics. Its noteworthy attributes include a large bandgap (Eg) of 4.8 eV, high theoretical critical breakdown field strength (EC) of 8 MV cm−1, and saturation velocity (νs) of 2 × 107 cm s−1, as well as high Baliga figures of merit (BFOM) of 3000. In addition, Ga2O3 has the advantages of large‐size substrates that can be achieved by low‐cost melt‐grown techniques. This review provides a partial overview of pivotal milestones and recent advancements in the Ga2O3 material growth and device performance. It begins with a discussion of the fundamental material properties of Ga2O3, followed by a description of substrate growth and epitaxial techniques for Ga2O3. Subsequently, the contact technologies between Ga2O3 and other materials are fully elucidated. Moreover, this article also culminates with a detailed analysis of Ga2O3‐based high voltage and high frequency power devices. Some challenges and solutions, such as the lack of p‐type doping, low thermal conductivity, and low mobility are also presented and investigated in this review.

Abstract High‐temperature in situ growth of Ga2O3 thin film on flexible substrates for flexible/portable electronic devices is never realized because the conventional polymer substrates cannot meet the thermal‐stability requirements. In the research, for the first time, Ga2O3 thin films are directly grown on SiOx/Al2Ox buffered Hastelloy substrates. With pulsed laser deposition under high temperature, as‐grown Ga2O3 thin films have a fabric texture with a preferred out‐of‐plane orientation along (−201) and a good field‐effect mobility of 18.07 cm2 V−1 s−1. The Ga2O3 coated tape is patterned with transistor arrays and exhibited good performance homogeneity. The representative transistor devices have a threshold voltage of ≈−2.75 V and a breakdown voltage of 116 V measured under a −20 V gate voltage. Moreover, the tape transistors also have good mechanical robustness. The transistors’ good electrical performance, high uniformity, and mechanical robustness suggest that the in situ deposition technique using Hastelloy tape is promising for fabricating various flexible Ga2O3 channeled electronic circuits. Furthermore, it is believed that this technique can be extended to other flexible semiconductor devices that require high‐temperature processing.

Abstract The fabrication and characterization of metal/BaTiO3/β‐Ga2O3 solar‐blind photodetectors are reported. β‐Ga2O3 is a promising material for solar‐blind photodetectors due to its large bandgap and the availability of low defect‐density melt‐grown substrates. In this work, structures are introduced that employ high‐permittivity dielectric/semiconductor heterojunctions to enhance the performance of a Schottky photodetector. It is shown that integrating the high‐k dielectric BaTiO3 reduces the dark current by ≈104, all but eliminates illumination induced Schottky barrier lowering, and increases the UV–vis rejection ratio by a factor greater than 9 × 103 compared to a Schottky photodetector. It is hypothesized that the high permittivity of the dielectric overcomes the influence of self‐trapped holes in Ga2O3 to reduce the peak electric field at the dielectric/metal interface, thereby eliminating the effects of Schottky barrier lowering on illuminated β‐Ga2O3 photodetectors. Additionally, it is hypothesized that the increase in the UV–vis rejection ratio is caused by the “dead layer” that forms at the BaTiO3/Pt interface.

Traditional optical communication systems rely on single narrow-band PDs, which can expose confidential information and data to potential eavesdropping in free space. With advancements in technology, even optical communication in the UV spectrum, invisible to the sun, faces risks of interception. Consequently, broad-band PDs that combine optical encryption with algorithmic encryption hold significant promise for secure and reliable communication. This study presents a photodetector based on TiO2–α-Ga2O3 heterostructures, prepared via direct oxidation and hydrothermal reaction, demonstrating self-powered UVC/UVA broad-band detection capabilities. The PD exhibits response peaks at approximately 250 and 320 nm, with R of 42.16 and 59.88 mA/W and D* of 8.21 × 1013 and 9.56 × 1013 Jones, respectively. Leveraging the superior optical response characteristics of UVC and UVA wavelengths, this device has been employed to develop a communication system designed for data transmission. The proposed system features two independent channels: one for data transmission using UVC and another for key distribution using UVA. Secure communication is ensured through specialized encryption algorithms. In summary, this work offers a straightforward, cost-effective, and practical method for fabricating self-powered UVC/UVA broad-band PDs. This PD provides new insights into the development of multi-purpose, multi-band secure optical communication devices and holds promise for integration into multifunctional optoelectronic systems in the future. [ABSTRACT FROM AUTHOR]

β-Ga2O3 is an ultra-wide bandgap semiconductor (Eg~4.8 eV) of interest for many applications, including optoelectronics. Undoped Ga2O3 emits light in the UV range that can be tuned to the visible region of the spectrum by rare earth dopants. In this work, we investigate the crystal lattice recovery of (2 ¯ 01) -oriented β-Ga2O3 crystals implanted with Yb ions to the fluence of 1 ×1014 at/cm2. Post-implantation annealing at a range of temperature and different atmospheres was used to investigate the β-Ga2O3 crystal structure recovery and optical activation of Yb ions. Ion implantation is a renowned technique used for material doping, but in spite of its many advantages such as the controlled introduction of dopants in concentrations exceeding the solubility limits, it also causes damage to the crystal lattice, which strongly influences the optical response from the material. In this work, post-implantation defects in β-Ga2O3:Yb crystals, their transformation, and the recovery of the crystal lattice after thermal treatment have been investigated by channeling Rutherford backscattering spectrometry (RBS/c) supported by McChasy simulations, and the optical response was tested. It has been shown that post-implantation annealing at temperatures of 700–900 °C results in partial crystal lattice recovery, but it is accompanied by the out-diffusion of Yb ions toward the surface if the annealing temperature and time exceed 800 °C and 10 min, respectively. High-temperature implantation at 500–900 °C strongly limits post-implantation damage to the crystal lattice, but it does not cause the intense luminescence of Yb ions. This suggests that the recovery of the crystal lattice is not a sufficient condition for strong rare-earth photoluminescence at room temperature and that oxygen annealing is beneficial for intense infrared luminescence compared to other tested environments. [ABSTRACT FROM AUTHOR]

It remains a big challenge to synthesize two-dimensional (2D) GaN material for applications in power nanodevices. Traditional synthetic methods require complex equipment and processes and time consuming. Here, we reported a two-step route to prepare polycrystalline 2D GaN film. The amorphous ultrathin Ga2O3 film was first exfoliated from the surface of liquid gallium. In a vapor phase reaction, 2D Ga2O3 film was then converted into 2D GaN film while maintaining the 2D morphology. Raman and high-resolution transmission electron microscope (HRTEM) analysis implies the successful synthesis of wurtzite-type GaN ultrathin film. This simple strategy proposed in this work will provide more opportunities for applications of GaN ultrathin film in many devices. [ABSTRACT FROM AUTHOR]

Al2O3 and Ga2O3 exhibit numerous crystal phases with distinct stabilities and material properties. However, the phase transitions among those materials are typically undesirable in industrial applications, making it imperative to elucidate the transition mechanisms between these phases. The configurational similarities between Al2O3 and Ga2O3 allow for the replication of phase transition pathways between these materials. In this study, we investigate the potential phase transition pathway of alumina from the θ-phase to the α-phase using stochastic surface walking global optimization based on global neural network potentials, while extending an existing Ga2O3 phase transition path. Through this exploration, we identify a novel single-atom migration pseudomartensitic mechanism, which combines martensitic transformation with single-atom diffusion. This discovery offers valuable insights for experimental endeavors aimed at stabilizing alumina in transitional phases. [ABSTRACT FROM AUTHOR]

It is crucial to develop advanced optoelectronic devices that incorporate multiple functions, including sensing, storage, and computing, which is considered at the forefront of semiconductor optoelectronics to meet emerging functional diversification. In this study, by stacking the n‐type Ga2O3 with the n‐type MoS2 flakes, a Ga2O3/MoS2 heterostructure optoelectronic device with high rectification ratio of ≈105 and on/off ratio of ≈108 is fabricated, which achieves high detectivity of 1.34 × 109 Jones and high responsivity of 28.92 mA/W. More importantly, the Ga2O3/MoS2 heterostructure device shows potential ability to integrate sensing and memorizing, simultaneously, which can be used as artificial neuromorphic synaptic. The device exhibits excellent photo‐induced synaptic functions including short‐term plasticity, long‐term plasticity, and paired‐pulse facilitation, realizing the ability to couple light and electrical signals by Pavlovian associative learning. At last, the device also demonstrates the information processing ability to act as optoelectronic logic gate AND by synergistically regulating the light on/off states and gate voltage. The research introduces an innovative strategy for the development of next‐generation optoelectronic devices which are highly integrated with sensing, memory, and logic processing functions, demonstrating great application prospects in constructing an efficient artificial neuromorphic visual and logic systems. [ABSTRACT FROM AUTHOR]

The effect of adsorption of ethanol and ammonia on the basicity of Ga2O3, MgO, and ZnO was examined via IR studies of CO2 adsorption. Ethanol reacts with OH groups on Ga2O3, and MgO, forming ethoxyl groups. The substitution of surface hydroxyls by ethoxyls increases the basicity of the neighbouring oxygen. The ethoxyl groups that also form on ZnO do not contain surface OH groups, but the mechanism of their formation is different. On ZnO, ethoxy groups are formed by the reaction of ethanol with surface oxygens. The presence of ethoxyls on ZnO decreases the basicity because some surface oxygens are already engaged in the bonding of ethoxyl groups. The effect of ammonia adsorption on basicity is different for each oxide. For Ga2O3, ammonia adsorption increases the basicity of neighbouring oxygen sites. Ammonia is not adsorbed on MgO; therefore, it does not change the basicity of this oxide. Ammonia adsorbed on ZnO forms coordination bonds with Zn sites; it does not change the number of basic sites but changes how carbonate species are bonded to surface sites. [ABSTRACT FROM AUTHOR]

Ga2O3‐based Ultraviolet‐C photodetector (UVCPD) is considered the most promising UVCPD at present and is divided into Metal‐Semiconductor‐Metal (MSM) and PN junction types. Compared with MSM‐PDs, PN‐PDs exhibit superior transient performance due to the built‐in electric field. However, current Ga2O3‐based PN‐PDs lack consideration for carrier collection and electric field distribution. In this study, PN‐PDs with an interdigital n‐Ga2O3 layer and finger electrodes are fabricated on p‐GaN/n‐Ga2O3 epilayers. Ultrafast response times of 31 µs (1/e decay) and 2.76 µs (fast component) are realized, which outperforms all Ga2O3 UVC‐PDs up to now. Under 0 V self‐powered, the responsivity (0.25 A W−1) of interdigital PD is enhanced by the interdigital electrode structure due to increasing carriers' collection length. Under bias, the performances of interdigital PD with 41.7 A W−1 responsivity and 8243 selection ratios are significantly elevated by enhancing the built‐in electric field in the Ga2O3 region, which is 34.76 and 39.4 times those of traditional PDs, respectively. The intrinsic enhancing mechanism of interdigital structure is also investigated by interdigital PDs with various electrode spacings and perimeters. In summary, this paper not only reports a highly performed interdigitated structure p‐GaN/n‐Ga2O3 UVCPDs, but also provides guidelines for structure design in Ga2O3‐based PN‐PDs. [ABSTRACT FROM AUTHOR]