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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 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]

Doping technology with stable carrier concentration regulation is a guarantee for optimizing β -Ga 2 O 3 -based high-power electronic devices and optoelectronic devices. In this study, β -Ga 2 O 3 homoepitaxial epitaxial films with stable and tunable electron concentrations were grown on Fe-doped (010)-oriented β -Ga 2 O 3 substrates by using metal-organic chemical vapor deposition (MOCVD). XRD shows that the basic bulk properties of β -Ga 2 O 3 film, i. e. the structure and crystal orientation, are stable with low Si-doping, however, its electrical properties vary remarkably depending on concentrations of Si ions incorporated by Si source flow rate during the film growth process. Hall measurement is utilized to confirm high-quality β -Ga 2 O 3 films with tunable electron concentration of 1017–1019 cm−3. As a consequence, the electron concentration-dependent behavior of β -Ga 2 O 3 Schottky barrier diodes (SBDs) was studied. The β -Ga 2 O 3 SBDs exhibited better forward current output electrical performance with reduction in built-in potential difference (V bi) from 2.4 V to 0.3 V and on-resistance (R on) from 257 Ω cm to 26 Ω cm. Our results suggest that stable and tunable electron concentration provides high-quality material assurance for constructing power electronic devices of Ga 2 O 3. • We achieved high-quality β -Ga 2 O 3 films with tunable electron concentrations of 1017–1019 cm−3 by using MOCVD. • We constructed high-performance lateral β -Ga 2 O 3 SBDs with tunable electronic properties. • The doped films exhibit good forward current output characteristics and a relatively fast current growth rate. [ABSTRACT FROM AUTHOR]

The influences of low growth temperatures (420–490 °C) on phase transition of Ga 2 O 3 films grown on Al 2 O 3 substrates by means of metal-organic chemical vapor deposition (MOCVD) are investigated here. The changes of crystal structure, phase composition, surface and cross-sectional morphologies are carried out by X-ray diffraction, atomic force microscope and field-emission scanning electron microscope to reveal the detail evolution from ε -phase to β -phase in Ga 2 O 3 films. The fluctuant Gibbs free energy change relying on growth temperature induces different growth mechanism of Ga 2 O 3 films. Furthermore, the ultraviolet photoresponse properties of different phase compositions for Ga 2 O 3 films are compared by constructing metal-semiconductor-metal photodetectors. It is found that mixture phase Ga 2 O 3 films express better photodetection performance than pure phase Ga 2 O 3 films due to the formation of built-in field within phase junction. This proposed regulation principle of Ga 2 O 3 phase transition provides a new route to high-performance photoelectric material. • Phase transition from ε -Ga 2 O 3 to β -Ga 2 O 3 was captured in a low growth temperature window of 420–490 °C by MOCVD. • Different Ga 2 O 3 phase compositions resulted in varying crystal structures, surface morphologies and UV sensing properties. • Ga 2 O 3 films with mixture phases demonstrated better photoresponse due to the formation of built-in field within phase junction. [ABSTRACT FROM AUTHOR]

• Solution processed VOx films obtain changeable conductivities in 2 orders of magnitude range. • Regulable conductivity of VO x enables effective hole-transport engineering in VO x /Ga 2 O 3 heterojunction. • Optimized VO x /Ga 2 O 3 photodetector demonstrates enhanced self-powered ultraviolet photodetection performance. The self-powered photodetection performance of the VO x /Ga 2 O 3 heterojunction photodetector could be effectively and positively regulated via the VO x hole transport layer by charge-carrier engineering, inducing the record PDCR of 1.08 × 108 and superhigh on/off ratio of 1.23 × 106. [Display omitted] As the carrier behavior is crucial to the photoelectric conversion process, the charge-carrier engineering could provide feasible strategy for high-performance photodetector (PD). Herein, self-powered ultraviolet PDs were constructed on VO x /Ga 2 O 3 (VGO) heterojunctions by adopting the solution processed VO x films as hole transport layer (HTL). Treated with different annealing ambients, the HTL demonstrated changeable conductivities due to the regulated crystallinities, phase structures and chemical valences, which further exerted influences on the VGO PDs inducing controllable photodetection properties. With effective hole transportation, low valence band barrier and large built-in field, the modulated VGO PDs achieved enhanced self-powered photodetection performance with photo-to-dark current ratio of 1.08 × 108, on/off ratio of 1.23 × 106, rejection ration (R 245 / R 400) of 3.12 × 104, responsivity of 28.9 mA/W and detectivity of 1.13 × 1014 Jones as well as rise/decay time of 57/74 ms. In consideration of the carrier-transport problems are commonly ubiquitous and particularly vital, our proposed HTL engineering method could open the high-performance route for self-powered ultraviolet PDs. [ABSTRACT FROM AUTHOR]