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Solar‐blind photodetectors have attracted extensive attention due to their advantages such as ultra‐low background noise and all‐weather. In this study, the planar Ti/Ga2O3/Au Schottky avalanche photodetector (APD) is fabricated based on β‐Ga2O3 epitaxial film on the sapphire substrate grown by metal–organic chemical vapor deposition. The Schottky APD exhibits a high responsivity of 9780.23 A W−1, an ultrahigh photo‐to‐dark current ratio of 1.88 × 107, an external quantum efficiency of 4.77 × 106%, a specific detectivity of 9.48 × 1014 Jones, with an ultrahigh gain of 1 × 106 under 254 nm light illumination at 60 V reverse bias, indicating high application potential for solar‐blind imaging. The superior photoresponse performances ascribe to the effective carrier avalanche multiplication, which contributes to the high photocurrent, and the high quality Schottky junction depletion, which leads to the low dark current. [ABSTRACT FROM AUTHOR]

The homoepitaxial Si-doped Ga2O3 film prepared by metal–organic chemical vapor deposition (MOCVD) was reported in this paper. The film thickness reached 4.5 microns, a relatively high value for MOCVD. The full width at half maxima of the (002) diffraction plane of the film was 26.3 arcsec, thus showing high crystalline quality. The film showed n−-type properties with a doping concentration of 3.6 × 1016 cm−3 and electron mobility of 137 cm2/V·s. In addition, the element composition and stress state of the film were characterized and analyzed. This indicates that the MOCVD, supporting high-quality, high-precision epitaxy, is promising for Ga2O3 power devices. [ABSTRACT FROM AUTHOR]

β-Ga 2 O 3 nanowire films were prepared on Si(111) substrate by selective area growth (SAG) using metal-organic chemical vapor deposition (MOCVD). A large-area periodic nano-hole array TiN mask was fabricated. The effects of MOCVD process parameters on SAG were discussed by calculating Ga supersaturation. It was found that the SAG is closely related to the selective area nucleation and inhibition of lateral growth. Transmission electron microscopy confirmed that β-Ga 2 O 3 nanowires have a preferential orientation of the (002) crystal plane. The sample after in-situ O 2 annealing showed an x-ray diffraction intensity increase of (400), (002), and (-111) crystal planes. On this basis, P–Si/β‐Ga 2 O 3 nanowire heterojunctions were fabricated and presented high resistance of the films. At a bias voltage of 20 V, the current decreased from 6.14 × 10−6 to 2.25 × 10−6 A. The MOCVD-based SAG paves a novel way to fabricate β-Ga 2 O 3 nanowire films with high surface-to-volume ratio and homogeneity. [ABSTRACT FROM AUTHOR]

• The DUV optoelectronic synapse was fabricated on the MOCVD-deposited a-GaO x film. • The information written into the bionic synapse is non-volatile. • The synapse can mimic the transition from short-term memory to long-term memory. Optoelectronic bionic synapses, integrating sensing and processing capabilities, help to break through the limitations of von Neumann structure and are promising in smart sensors, AI robots etc. fields. Here, we fabricated a deep ultraviolet (DUV) optoelectronic bionic synapse with an amorphous gallium oxide (a-GaO x) film deposited by metal–organic chemical vapor deposition (MOCVD). DUV illumination pulses could be facilely written into the bionic synapse, and the written information exhibits non-volatility. By manipulating the illumination pulse number, the pulse width, and the pulse power density, the synapse is capable of transitioning from short-term memory (STM) to long-term memory (LTM), effectively emulating the learning-memory behavior of human brains. [ABSTRACT FROM AUTHOR]

[Display omitted] • The surface chemical composition of β-Ga 2 O 3 films is discussed in depth. • The component of O 1s with the binding energy around 531.8 eV is attributed to surface lattice O atoms. • The defects inside the β-Ga 2 O 3 films were analyzed by HRTEM. β gallium oxide (β-Ga 2 O 3) is an ultrawide bandgap semiconductor with great potential for solar-blind ultraviolet detection, power devices, and gas sensing. However, the understanding of the surface properties of β-Ga 2 O 3 remains insufficient. Here, epitaxial growth of β-Ga 2 O 3 films was carried by metal–organic chemical vapor deposition (MOCVD) on sapphire substrates. The surface chemical composition, surface layer crystalline properties, and surface morphology of the β-Ga 2 O 3 films were discussed and analyzed in detail. By comparing the atomic ratios of O/Ga, the surface morphology, and the crystalline properties of the films, we attribute the component of O 1s with the binding energy around 531.8 eV to surface lattice O atoms. Moreover, the one-dimensional defects inside the surface layers and the near-interface regions of the films were observed at atomic scale by high resolution transmission electron microscopy (HRTEM). By comparing the lattice fringes of different facets, the geometric phase uniformity, and the distribution of strain, we found that the crystalline quality of the surface layers is much higher than the near-interface regions. [ABSTRACT FROM AUTHOR]

Monoclinic gallium oxide (β-Ga 2 O 3) has attracted wide attention due to its low-cost single crystal and excellent optoelectronic properties. However, the low specific surface area and high defect density of β-Ga 2 O 3 thin films result in weak light-matter interaction and poor crystal quality, seriously hindering their applications. In this article, the growth of high light-trapping β-Ga 2 O 3 nanorod (NR) film on GaAs substrates by metal-organic chemical vapor deposition (MOCVD) is demonstrated. The GaAs substrates were pre-treated by thermal oxidation (TO) to produce a β-Ga 2 O 3 seed layer. The effect of MOCVD growth conditions on the morphology of β-Ga 2 O 3 NR films is investigated. The growth mechanism of β-Ga 2 O 3 NR films is studied in detail. X-ray diffraction, Raman, and photoluminescence were employed to study the crystal and optical properties of β-Ga 2 O 3 NR films. A significant light-trapping effect with a 40 % reduction in optical reflectance at the wavelength of 254 nm is observed. The results show that the β-Ga 2 O 3 NR films exhibit strong light-matter interaction and have potential in optoelectronic applications. [ABSTRACT FROM AUTHOR]

• SBUV photodetector based on β-Ga 2 O 3 /n-Si isotype heterojunction was fabricated. • Typical rectification behavior and stable light switching property were achieved. • The photodetector showed high PDCR and fast response speed. • The photodetector had excellent sensitivity and selectivity to SBUV light. In this study, β-Ga 2 O 3 /n-Si isotype heterojunction was fabricated to form a solar-blind ultraviolet photodetector by depositing β-Ga 2 O 3 film on n-type Si substrate using metal-organic chemical vapor deposition. Photodetection properties of the photodetector were investigated systematically. The fabricated isotype heterojunction photodetector exhibited typical rectifying characteristics and excellent light on-off switching performance. Under 254 nm illumination, the photodetector showed the photo-to-dark current ratio of 591.38 at −20 V bias. Meanwhile, fast response speed with rise time (τ r 1 , τ r 2 ) of (0.20 s, 1.81 s) and decay time (τ d 1 , τ d 2 ) of (0.02 s, 5.12 s) at −20 V bias was obtained. The results indicate that the photodetector based on β-Ga 2 O 3 /n-Si isotype heterojunction has excellent sensitivity and selectivity to solar-blind ultraviolet light. [ABSTRACT FROM AUTHOR]

A solar-blind ultraviolet photodetector based on p-Si/n-β-Ga 2 O 3 :Si heterojunction, using the Si-doped β-Ga 2 O 3 as the n-type layer, was fabricated successfully by metal-organic chemical vapor deposition (MOCVD). The current-voltage and photoresponse characteristics of photodetector were investigated. The fabricated p-Si/n-β-Ga 2 O 3 :Si heterojunction photodetector exhibited typical rectification behavior and good solar-blind ultraviolet photoresponse. Sensitive photodetection of current at the reverse bias voltage and stable on-off switching performance were achieved. The photodetector showed a responsivity of 3.76 A/W and a photo-to-dark current ratio of 37.9 under 254 nm illumination. The rise time constants (τ r 1 , τ r 2) and the decay time constants (τ d 1 , τ d 2) of the photodetector under 254 nm illumination at the reverse voltage of − 20 V were estimated to be (0.30 s, 0.76 s) and (0.15 s, 6.15 s), respectively. The fabricated p-Si/n-β-Ga 2 O 3 :Si heterojunction photodetector displayed relatively faster response speed compared to the reported photodetectors based on p-Si/undoped β-Ga 2 O 3 heterojunction. The results indicate that photodetectors based on p-Si/n-β-Ga 2 O 3 :Si heterojunction have potential development for the high-performance solar-blind ultraviolet photodetectors. [ABSTRACT FROM AUTHOR]