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Nitrogen (N) doping engineering is considered a promising approach to achieve p-type conductivity of Ga2O3 films. However, the defect self-compensation effect has been a major obstacle in this field. In this work, we propose a straightforward and environmentally friendly strategy to obtain a doped surface on β-Ga2O3 films via nonthermal N plasma-based treatment. By substituting nitrogen with oxygen, acceptor impurity levels are formed near the valence band, and self-trapped exciton recombination occurs, thereby enhancing the luminescence effect related to acceptor defects. Meanwhile, although achieving stable p-type conduction with N dopant acceptors remains challenging, the surface conductive properties are enhanced by the defect compensation of oxygen vacancy (VO) donor defects. Therefore, detailed investigations into the surface defect compensation of N-doped Ga2O3 thin films are of great research potential for device applications. [ABSTRACT FROM AUTHOR]

Ga2O3, with its large band gap, is a promising material suitable for utilization in solar-blind photodetection. Sapphire with a higher lattice match with Ga2O3 was used as the substrate for epitaxial growth of Ga2O3. Here, the epitaxial layers of Ga2O3 were deposited by MOCVD on patterned sapphire substrates. The structure of epitaxial Ga2O3 layers on patterned substrates has been identified by X-ray diffractometry. To investigate the influence of the patterned substrates on the formation of epitaxial layers, thin Ga2O3 layers were grown on a flat sapphire substrate under the same conditions. Both types of samples were β-phase. However, no improvement in the layers' crystalline quality was discovered when utilizing patterned sapphire substrates. In addition, the performance of the obtained two types of Ga2O3 photodetectors was compared. The photoelectric properties, such as responsivity, response speed, and detection capability, were different in the case of flat samples. [ABSTRACT FROM AUTHOR]

A high-quality β-Ga2O3 film was grown on a (111) GaAs substrate using the metal organic chemical vapor deposition method. The band alignment of the β-Ga2O3/GaAs heterojunction interface was determined by x-ray photoelectron spectroscopy. The energy-band structure of β-Ga2O3/GaAs was constructed based on the binding energies of Ga 3d and As 3d core levels as well as valence band maximum values. The valence band offset was determined to be 3.50 ± 0.05 eV. As a consequence, a type-ΙΙ heterojunction with a conduction band offset of 0.12 ± 0.05 eV was determined in the present study. The accurate determination of the band alignment of the β-Ga2O3/GaAs heterojunction provided useful information for the application in β-Ga2O3/GaAs-based devices. [ABSTRACT FROM AUTHOR]

Ga2O3 has generated considerable interest as a wide bandgap semiconductor and is used for solar-blind deep ultraviolet photodetectors. Additionally, graphene serving as a transparent electrode material can improve device performance. However, due to defects at the contact interface between graphene and Ga2O3, existing devices based on graphene/Ga2O3 are liable to elevated dark currents. In this work, we constructed a graphene/β-Ga2O3/Ag asymmetric Schottky junction photodetector, which addresses this issue. Taking advantage of the asymmetric structure design to suppress dark current and the transparent graphene electrode increasing the carrier collection efficiency, the device achieved an outstanding responsivity of 44.09 A W−1, a high detectivity of 5.84 × 1012 Jones, a remarkable external quantum efficiency of 2.15 × 104%, and a fast response time of 99.60 ms/27.74 ms. More importantly, owing to reverse bias voltage on the high barrier side, it possesses a low dark current of 12.09 pA with a light-to-dark ratio of up to 104. All in all, the graphene/β-Ga2O3/Ag asymmetric Schottky junction photodetector has considerable potential as a deep ultraviolet detector. [ABSTRACT FROM AUTHOR]

In this study, 2-in. wafer-scale large-area β-Ga2O3 epitaxial films were fabricated on c-plane sapphire substrates via metal-organic chemical vapor deposition. X-ray diffraction, atomic force microscopy, field-emission scanning electron microscope, and photoelectric properties were carried out to disclose the material uniformity of large-scale β-Ga2O3 epitaxial films. Even with film thickness as thick as 1.5 μm, the grown β-Ga2O3 epitaxial films demonstrated high crystal quality with an average FWHM of 1.71° and a standard deviation (SD) of 0.035, smooth surface morphology with an average root-mean-square of 5.45 nm and a slight deviation of 0.09 nm, outstanding thickness uniformity with an average film thickness of 1.55 μm and SD value of only 28 nm. Furthermore, each β-Ga2O3 photodetector on epitaxial wafer expressed uniform stability of the photoelectric performance distribution. High material uniformity of our fabricated large-scale β-Ga2O3 epitaxial films lays a solid foundation for its future mass production of Ga2O3-based devices. [ABSTRACT FROM AUTHOR]

Proteins of the alkylation B (AlkB) superfamily show RNA demethylase activity removing methyl adducts from N6‐methyladenosine (m6A). m6A is a reversible epigenetic mark of RNA that regulates human virus replication but has unclear roles in plant virus infection. We focused on Potyvirus—the largest genus of plant RNA viruses—and report here the identification of AlkB domains within P1 of endive necrotic mosaic virus (ENMV) and an additional virus of a putative novel species within Potyvirus. We show that Nicotiana benthamiana m6A levels are reduced by infection of plum pox virus (PPV) and potato virus Y (PVY). The two potyviruses lack AlkB and the results suggest a general involvement of RNA methylation in potyvirus infection and evolution. Methylated RNA immunoprecipitation sequencing of virus‐infected samples showed that m6A peaks are enriched in plant transcript 3′ untranslated regions and in discrete internal and 3′ terminal regions of PPV and PVY genomes. Down‐regulation of N. benthamiana AlkB homologues of the plant‐specific ALKBH9 clade caused a significant decrease in PPV and PVY accumulation. In summary, our study provides evolutionary and experimental evidence that supports the m6A implication and the proviral roles of AlkB homologues in Potyvirus infection. [ABSTRACT FROM AUTHOR]

A practical method for organic–inorganic hybrid heterojunction photodetector by spin-coating the cobalt phthalocyanine (CoPc) solution onto the β-gallium oxide (β-Ga2O3) film is available to realize the sensitive detection of ultraviolet light signals. We have carefully measured and calculated the optoelectronic performance of the prepared device. The device demonstrates excellent rectification characteristics under different light intensities, and the rectification ratio reaches 144.96 under 900 μW/cm2 at ±5 V. Benefiting from the construction of CoPc/Ga2O3 heterojunction, the device shows an extremely low dark current of 5.73 fA, a high detectivity of 1.92 × 1017 Jones, a responsivity of 18.4 mA/W, and a high light-to-dark current ratio of 3.76 × 106. In addition, the intrinsic physical mechanism of the device is investigated through the energy band diagram under different conditions. The device is equipped with the possibility to work under self-powered mode and has good stability in the air environment. [ABSTRACT FROM AUTHOR]

Can the modulation effect of charge-carrier transfer be inherited from a single layer to its heterojunction structure? Certainly, the answer is yes. Herein, we experimentally verify that the photodetection performance modulation effect of oxygen vacancy (Vo) is transmitted from the ε-Ga2O3 layer to the PEDOT:PSS/ε-Ga2O3 (PGO) hybrid heterojunction. By adopting the annealed ε-Ga2O3 films, whose Vo concentrations are remolded by annealing ambients, the constructed PGO photodetectors (PDs) demonstrate regulable self-powered performance. As the Vo defects decrease, the photodetection properties are effectively enhanced with a high photo-to-dark current ratio of 2.37×107, an excellent on/off switching ratio of 6.45×105, fast rise/decay time of 121/72 ms, a large responsivity of 67.9 mA/W, superior detectivity of 9.2×1013 Jones, an outstanding external quantum efficiency of 33.2%, and a high rejection ratio (R250/R400) of 5.96×106 at 0 V in PGO-O2 PD. The better photoresponse is attributed to the less Vo defect concentration in the ε-Ga2O3 layer, which could favor the lower electron-trapping probability and a more efficient charge-carrier transfer. Considering the universality of Vo defects in oxide materials, the proposed regulation strategy of photoresponse will open the route of high self-powered performance for next-generation ultraviolet PDs. [ABSTRACT FROM AUTHOR]

A novel p–i–n self-powered solar-blind UV photodetector based on p-type spiro-MeOTAD (spiro), Ga2O3, and n-type Si is fabricated. The p-type spiro film is spin-coated on the surface of the Ga2O3 film deposited on a Si wafer via a metal–organic chemical vapor deposition (MOCVD) system. Benefitting from the superior carrier-separation ability of the double built-in electric fields, the effective carrier transport of the novel vertical structure and the high solar-blind UV transmittance of the spiro film, the self-powered responsivity of the p–i–n-type photodetector based on spiro/Ga2O3/Si increases to 4.43 mA W−1 under UV light (λ = 254 nm), which is ∼54-fold that of the Ga2O3/Si photodetector (0.22 mA W−1). Meanwhile, the response speed (0.03/0.196 s) of the p–i–n device is also dramatically improved by introducing the spiro layer. The reported achievements of our work provide a new way to construct a high-sensitivity self-powered UV photodetector for photovoltaic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

By acting as the trapping centers during charge carrier transfer, oxygen vacancy (VO) plays a critical role in oxide photoelectric devices. Herein, a post-annealing method was introduced to perfect the photodetection performances of ε-Ga2O3 photodetectors (PDs) by improving the film quality and modulating the VO defect concentration. The native oxygen-deficient ε-Ga2O3 epitaxial films fabricated via metal–organic chemical vapor deposition become highly dense and VO-less after oxidation annealing, leading to an enhanced performance, while they become VO-rich after reduction annealing to depress the PD property. Compared with the pristine PD, the crucial parameters of the devices with a lower VO concentration have been improved by 1–6 magnitude with a high photo-to-dark current ratio of 1.06 × 108, a large responsivity of 1.368 A W−1, an excellent detectivity of 9.13 × 1014 Jones, a superior linear dynamic range of 176.7 dB and an outstanding external quantum efficiency of 666.5% and a record-high rejection ratio (R240/R400) of 1.80 × 107. As the VO defect is commonly ubiquitous in oxide materials, our investigation of regulating the VO concentrations in ε-Ga2O3 and then exerting influences on the PD capabilities will provide principles for designing high-performance photoelectric devices. [ABSTRACT FROM AUTHOR]