Search Results (421)

Mg-doped gallium oxide films were prepared on single crystal sapphire substrates through radio frequency magnetron sputtering technology, and then AlN films of different thicknesses were deposited on them as passivation layers. Finally, Pt interdigitated electrodes were prepared through mask plate and ion sputtering technology to make metal–insulator–semiconductor–insulator–metal (MISIM) photodetectors. The influence of the AlN passivation layer on the optical properties and photodetection performance of the device was investigated using UV-Vis (ultraviolet-visible absorption spectroscopy) spectrophotometer and a Keith 4200 semiconductor tester. The device’s performance was significantly enhanced. Among them, the MISIM-structured device achieves a responsivity of 2.17 A/W, an external quantum efficiency (EQE) of 1100%, a specific detectivity (D*) of 1.09 × 10¹² Jones, and a photo-to-dark current ratio (PDCR) of 2200. The results show that different thicknesses of AlN passivation layers have an effect on the detection performance of Mg-doped β-Ga₂O₃ films in the UV detection of the solar-blind UV region. The AlN’s thickness has little effect on the bandgap when it is 3 nm and 5 nm, and the bandgap increases at 10 nm. The transmittance of the film increases with the increase in AlN thickness and decreases when the AlN’s thickness increases to 10 nm. The photocurrent exhibits a non-monotonic dependence on AlN thickness at 10 V, and the dark current gradually decreases. The thickness of the AlN passivation layer also has a significant impact on the response characteristics of the detector, and the response characteristics of the device are best when the thickness of the AlN passivation layer is 5 nm. The responsiveness, detection rate, and external quantum efficiency of the device first increase and then decrease with the thickness of the AlN layer, and comprehensive performance is best when the thickness of the AlN passivation layer is 5 nm. The reason is that the AlN layer plays a passivating role on the surface of Ga₂O₃ films, reducing surface defects and inhibiting its capture of photogenerated carriers, while the appropriate thickness of the AlN layer increases the barrier height at the semiconductor interface, forming a built-in electric field and improving the response speed. Finally, the AlN layer inhibits the adsorption and desorption processes between the photogenerated electron–hole pair and O₂, thereby retaining more photogenerated non-equilibrium carriers, which also helps enhance photoelectric detection performance. Full article

Ultra-bandgap semiconductor material, β-gallium oxide (β-Ga₂O₃), has great potential for fabricating the next generation of high-temperature, high-voltage power devices due to its superior material properties and cost competitiveness. In addition, β-Ga₂O₃ has the advantages of high-quality, large-size, low-cost, and controllable doping, which can be realized by the melt method. It has a wide bandgap of 4.7–4.9 eV, a large breakdown field strength of 8 MV/cm, and a Baliga figure of merit (BFOM) as high as 3000, which is approximately 10 and 4 times that of SiC and GaN, respectively. These properties enable β-Ga₂O₃ to be strongly competitive in power diodes and metal-oxide-semiconductor field-effect transistor (MOSFET) applications. Most of the current research is focused on electrical characteristics of those devices, including breakdown voltage (V_BR), specific on-resistance (R_ON,SP), power figure of merit (PFOM), etc. Considering the rapid development of β-Ga₂O₃ diode technology, this review mainly introduces the research progress of different structures of β-Ga₂O₃ power diodes, including vertical and lateral structures with various advanced techniques. A detailed analysis of Ga₂O₃-based high-voltage power diodes is presented. This review will help our theoretical understanding of β-Ga₂O₃ power diodes as well as the development trends of β-Ga₂O₃ power application schemes. Full article

This study systematically investigated the effects of oxygen plasma treatment on oxygen vacancy defects in sputtered β-gallium oxide (β-Ga₂O₃) films and their corresponding ultraviolet (UV) detection performance. The sputtered β-Ga₂O₃ film subjected to 1 min of oxygen plasma treatment exhibited optimal photodetection properties. Compared to the untreated sample, the dark current was reduced by approximately one order of magnitude to 0.378 pA at 10 V bias. It exhibited an 86% (from 2.92 s to 0.41 s) decrease in response time, a 41.6% increase in photocurrent, a very high photo-to-dark current ratio of 9.18 × 10⁵, and a specific detectivity of 2.62 × 10¹⁰ cm·Hz^1/2W⁻¹ under 254 nm UV illumination intensity of 799 μW/cm² at 10 V bias. Notably, appropriate oxygen plasma treatment minimizes electron capture, enhances the separation and collection of photogenerated carriers, and suppresses the persistent photoconductivity (PPC) effect, thus ultimately shortening the response time. Oxygen plasma processing thus provides an effective approach to fabricating high-performance β-Ga₂O₃ solar-blind photodetectors (SBPDs). Full article

Gallium oxide-based devices are critical in various applications, including industrial safety, the gas and petroleum sectors, and research environments. However, the deep etching process has not been thoroughly explored. Key parameters such as etching rate, selectivity, uniformity, isotropic/anisotropic behavior, and surface properties all influence the effectiveness of the etching process and its reproducibility. This research was motivated by the need for efficient fabrication processes, particularly in applications where sensors must operate in harsh environments, due to their instead of owning to low leakage current density of their power devices. In this study, we studied a deep etching technique for Ga₂O₃, focusing on the chemical stability of the two planes and identifying suitable protocols that could enhance etching depth via a dry-etching process. A deep ion-etching process for Ga₂O₃ was successfully developed, achieving deep etches of 6.97 µm in the Ga₂O₃. These advancements pave the way for high-aspect-ratio Ga₂O₃ nanostructures, offering new possibilities for robust nanosensors in harsh environments. Full article

This article presents a remarkable achievement: a gallium oxide-based, non-metallic, fully transparent, and self-powered solar-blind ultraviolet photodetector. We have replaced the traditional metal electrode with gallium-doped zinc oxide (GZO), a transparent conductive oxide, for this transparent purpose. Gallium oxide, a wide-bandgap material suitable for solar-blind detection, is used as the active layer. Glass and natural mica are used for the transparent substrate. The gallium oxide thin film is deposited by RF sputtering at room temperature, with polycrystalline orientation, and the top integrated GZO electrode is also prepared at room temperature using the same technique. This simple two-layer structure device maintains a transmittance of over 88% in the visible spectrum for both substrates, a truly impressive performance. Both glass and mica substrates exhibit self-powered photoresponsivity at 265 nm with responsivities of 8.8 × 10⁻⁹ and 4.4 × 10⁻⁷ (A/W), operating with an externally applied voltage of 1 V and boasting a responsivity of around two orders of magnitude with rise/fall times less than 10 s. An X-ray diffractometer, ultraviolet–visible spectroscopy, semiconductor analysis, and a semiconductor electron microscope are used for material analysis and device performance. This article presents a transparent gallium oxide solar-blind photodetector with a simple structure. Our research explains the exceptional transmittance of non-metal electrodes with gallium oxide solar-blind photodetectors, setting a new standard in the field. Full article

This paper presents a study on the propagation of acoustic waves in gallium nitride (GaN) layers deposited on sapphire substrate. The influence of GaN layer thickness and the configuration of interdigital transducers (IDTs) on the generation and propagation of different surface wave modes, including Rayleigh, Sezawa, and Love waves, was analyzed. Experimental measurements in the 100 MHz–6 GHz range were complemented by numerical simulations using the finite element method (FEM). The results demonstrated a strong dependence of wave characteristics on technological parameters, particularly the quality of the GaN–sapphire interface. The data obtained can be utilized for optimizing the design of acoustic sensors, resonators, and RF filters. Full article

Gallium oxide (Ga₂O₃) is a promising ultra-wide-bandgap (UWBG) material with exceptional transport properties, including a large breakdown voltage, making it ideal for high-voltage power device applications. Recently, Ga₂O₃ has gained significant attention as a next-generation material for electronic device fabrication aimed at advancing power electronics. In this paper, we investigate the effect of a Ga₂O₃ buffer layer on a GaN-based high electron mobility transistor (HEMT), focusing on output I–V characteristics and surface charge effects. Furthermore, we explore an advanced approach to enhance HEMT performance by utilizing polarization-induced two-dimensional electron gas (2DEG), as an alternative to conventional doping methods. A III-N/Ga₂O₃ heterostructure is proposed as a distinctive electrical property and a cost-effective UWBG solution. To evaluate the associated effects, we simulate a two-dimensional (2D) Ga₂O₃/GaN HEMT structure incorporating surface charge models. Our results confirm that 2DEG formation near the surface creates a conductive channel due to polarization-induced dipoles at the interface. The simulations also show a negative shift in the threshold voltage, a condition typically unattainable without oxidation layers or doping. Finally, we analyze the potential of AlGaN/Ga₂O₃-based HEMTs for future power electronic applications. Full article

Mycobacterium avium complex (MAC) infections present significant therapeutic challenges due to their inherent antibiotic resistance, demanding innovative treatment approaches. This study investigated the antimicrobial and antioxidant potential of a novel compound, Fullerene Gallium Phosphonate (FGP), and compared its effects against a previously tested similar compound, Fullerene Disodium Phosphonate (FDSP). Results of experiments using MAC cultures and infected THP-1 macrophages treated with varying FGP and FDSP concentrations (1, 10, 100 µg/mL) revealed that FGP demonstrated greater efficacy than FDSP in reducing M. avium colony-forming units (CFU), achieving a nearly 3-fold reduction by day 8, compared to a 2-fold decrease with FDSP. In infected macrophages, FGP significantly decreased bacterial load at 1 and 10 µg/mL (p < 0.01). FGP also lowered oxidative stress, reflected by a significant reduction in malondialdehyde (MDA) levels on day 4 (p < 0.05) and decreased IL-6 (2-fold) and TNF-α levels (3-fold) by day 8, indicating both antimicrobial and anti-inflammatory effects. However, FGP paradoxically increased MAC burden at its highest concentration and showed no significant difference in efficacy of different concentrations. These findings suggest that FGP may serve as a promising candidate for antimycobacterial therapy with dual antibacterial and antioxidant effects. Further research is crucial to fully elucidate its mechanism of action and find the optimal therapeutic window. Full article

Volatile organic compounds (VOCs) are major contributors to air pollution, posing significant environmental and health risks. Here we report gallium oxide (Ga₂O₃)-coated mesh as a practical immobilized photocatalyst for VOC degradation under UVC irradiation. A 3 wt.% Ga₂O₃ suspension was spray-coated onto the stainless-steel mesh, yielding a uniform coating with strong adhesion properties, as confirmed by cross-sectional analysis. Under identical conditions to a Ga₂O₃ powder, the Ga₂O₃-coated mesh delivered comparable VOC degradation rates and first-order kinetics while offering superior mechanical stability and ease of handling. Over five consecutive cycles, 93–95% of the VOC degradation efficiency was retained with negligible loss of activity, confirming excellent reusability. Fourier Transform Infrared Spectroscopy (FTIR) spectra of the Ga₂O₃-coated mesh after degradation reaction revealed significantly reduced VOC peaks, such as C=O and C-O absorption peaks, whereas spectra for the uncoated mesh changed only slightly. These results indicate that VOC degradation originates from the coated photocatalyst. Overall, these findings demonstrate that Ga₂O₃-coated mesh is a highly efficient, stable, and reusable platform for VOC removal, suggesting its potential for practical applications in air purification and environmental remediation. Full article

Beta-gallium oxide (β-Ga₂O₃) is a semiconductor with an ultra-wide bandgap, high optical transparency, and excellent electrical properties, which can be finely tuned for a wide range of electronic devices. This study optimized the process conditions for fabricating β-Ga₂O₃ thin films with desired electrical characteristics. β-Ga₂O₃ films were deposited on (100) Si substrates via RF magnetron sputtering with varying O₂ flow rates and post-annealed at temperatures ranging from 600 °C to 800 °C. The structural and electrical properties of the films were analyzed using X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM), and Hall effect measurements. The XRD results confirmed the formation of nanocrystalline β-Ga₂O₃, with variations in peak intensities and shifts observed based on O₂ flow rates. The films exhibited carrier concentrations exceeding 5 × 10²² cm⁻³, mobilities ranging from 50 to 115 cm²/Vs, and resistivity around 1 × 10⁻⁶ Ω⋅cm. This study demonstrates that the electrical properties of β-Ga₂O₃ thin films can be modulated during the deposition and post-annealing processes. The ability to control these properties underscores the potential of β-Ga₂O₃ for advanced applications in high-performance high-power devices and optoelectronic devices such as deep ultraviolet photodetectors. Full article

Volatile organic compounds (VOCs), including benzene, toluene, and formaldehyde, are hazardous air pollutants that require efficient and sustainable mitigation strategies. Photocatalytic degradation of VOCs offers a promising pathway; however, its performance is strongly influenced by multiple operational parameters. Here, we present a systematic investigation of toluene degradation under ultraviolet-C (UVC) irradiation across controlled temperatures using Ga₂O₃ as a photocatalyst. A comprehensive analysis revealed that elevated temperatures enhanced photocatalytic activity by accelerating chemical reaction rates. However, further temperature increases led to a decrease in performance due to a reduction in the reactant adsorption rate. An optimal operating temperature was identified, at which the balance between chemical reaction rates and reactant adsorption yields the highest degradation efficiency. These findings demonstrate Ga₂O₃ as a promising photocatalyst and provide fundamental insights into the temperature-dependent photocatalytic mechanisms governing VOC removal in practical environmental applications. Full article

Hexagonal boron nitride (h-BN) possesses a unique combination of a wide bandgap, high thermal conductivity, and chemical inertness, making it a key insulating and thermal management material for advanced electronics and nanocomposites. However, its intrinsic hydrophobicity and strong interlayer van der Waals forces severely limit exfoliation efficiency and dispersion stability, particularly in scalable liquid-phase processes. Here, we report a synergistic exfoliation strategy that integrates acid-induced hydroxylation with gallium (Ga) intercalation to achieve high-yield (>80%) production of ultrathin (<4 nm) hydrophilic h-BN nanosheets. Hydroxylation introduces abundant -OH groups, expanding interlayer spacing and significantly increasing surface polarity, while Ga intercalation leverages its native Ga₂O₃ shell to form strong interfacial interactions with hydroxylated basal planes. This oxide-mediated adhesion facilitates efficient layer separation under mild sonication, yielding nanosheets with well-preserved lateral dimensions and exceptional dispersion stability in polar solvents. Comprehensive characterization confirms the sequential chemical and structural modifications, revealing the crucial roles of hydroxylation-induced activation and Ga₂O₃ assisted wettability enhancement. This combined chemical activation–soft metallic intercalation approach provides a scalable, solution-processable route to high-quality h-BN nanosheets, opening new opportunities for their integration into dielectric, thermal interface, and multifunctional composite systems. Full article

H₂ has become one of the most attractive alternatives to replace fossil fuels in clean energy production, but large-scale production remains a challenge. A key step toward this goal is to develop new efficient electrocatalysts for H₂ production. This work presents a new mixed metal oxides-decorated CNT paste electrode (MMO@C), which is highly electrocatalytic, for use in the hydrogen evolution reaction (HER). MMO@C is synthesized by a solvothermal method and used as an easy-to-prepare paste electrode. XPS and X-ray analysis indicate that the electrocatalyst corresponds to a mixed surface of Ga₂O₃-CuO-Cu₂O-Cu(OH)₂@C. The MMO@C electrocatalyst shows a positive E_o of 0.12 V vs. RHE at −10 mA cm⁻² towards the HER in a neutral medium. In neutral and alkaline media, the presence of Ga₂O₃ facilitates the reduction of CuO to Cu(I) species, which is followed by the formation of Cu(s) active sites. Therefore, the excellent electrocatalytic performance toward the HER in a neutral medium is attributed to the synergistic effect between gallium and copper oxides on the electrode surface. The prominent H₂ production using MMO@C electrocatalyst is 1.31 × 10⁻² mol cm⁻², with a turnover number (TON) of 39,423, a turnover frequency (TOF) of 13,141 h⁻¹, and a faradaic efficiency (FE) of 94.3%. Although the Tafel slope reveals slow reaction kinetics, the outstanding onset potential allows for the coupling of the electrocatalyst to renewable energy production systems, making it an attractive candidate for producing green H₂ and for application in membrane water electrolyzers. Full article

Ga₂O₃ is an ultra-wide bandgap semiconductor material that has attracted significant attention for deep ultraviolet photodetector applications due to its excellent UV absorption capability and reliable stability. In this study, a novel plasma-enhanced thermal oxidation (PETO) method has been proposed to fabricate Ga₂O₃ thin films on the GaN/sapphire substrate in the gas mixture of Ar and O₂. By adjusting the O₂-to-Ar ratio (2:1, 4:1, and 8:1), the structural, morphological, and photoelectric properties of the synthesized Ga₂O₃ films are systematically studied as a function of the oxidizing atmosphere. It is demonstrated that, at an optimal O₂-to-Ar ratio of 4:1, the synthesized Ga₂O₃ thin film has the largest grain size of 31.4 nm, the fastest growth rate of 427.5 nm/h, as well as the lowest oxygen vacancy concentration of 16.61%. Furthermore, the nucleation and growth of Ga₂O₃ thin films on the GaN/sapphire substrate by PETO is proposed. Finally, at the optimized O₂-to-Ar ratio of 4:1, the metal–semiconductor–metal-structured Ga₂O₃-based photodetector achieves a specific detectivity of $2.74\times {10}^{13}$ Jones and a solar-blind/visible rejection ratio as high as 116 under a 10 V bias. This work provides a promising approach for the cost-effective fabrication of Ga₂O₃ thin films for UV photodetector applications. Full article

Gallium oxide (Ga₂O₃)-based memristors are gaining traction as promising candidates for next-generation electronic devices toward in-memory computing, leveraging the unique properties of Ga₂O₃, such as its wide bandgap, high thermodynamic stability, and chemical stability. This review explores the evolution of memristor theory for Ga₂O₃-based materials, emphasising capacitive memristors and their ability to integrate resistive and capacitive switching mechanisms for multifunctional performance. We discussed the state-of-the-art fabrication methods, material engineering strategies, and the current challenges of Ga₂O₃-based memristors. The review also highlights the applications of these memristors in memory technologies, neuromorphic computing, and sensors, showcasing their potential to revolutionise emerging electronics. Special focus has been placed on the use of Ga₂O₃ in capacitive memristors, where their properties enable improved switching speed, endurance, and stability. In this paper we provide a comprehensive overview of the advancements in Ga₂O₃-based memristors and outline pathways for future research in this rapidly evolving field. Full article