As a promising ultra-wide bandgap (UWBG) semiconductor, gallium oxide (Ga2O3) has recently aroused increasing attention in the area for high-power electronics, power switch for radio frequency (RF) operation, and solar blind UV detectors. The β-phase of Ga2O3 is deemed as a potential candidate for next generation high-power electronics due to its high theoretical breakdown electric field (8 MV cm−1), UWBG (4.8 eV), and large Baliga’s figure of merit. Owing to the intensive research efforts across the world since 2013, gallium oxide transistors recently make rapid advances in device design and performance. Until now, high quality large-size bulk Ga2O3 and n-type epi products are successively coming onto the market, as well as there are gratifying progress worldwide to develop more complex epi structures, including β-(Al x Ga1−x )2O3/Ga2O3, β-(In x Ga1−x )2O3/Ga2O3, n-Ga2O3/p-NiO, β-Ga2O3/4H-SiC heterostructures et al. In this paper, the basic physical properties of Ga2O3, and the recent research process of Ga2O3 based transistors field-effect transistor (FET) for high-power electronics and RF are introduced. Furthermore, various state-of-the-art structures and process used in Ga2O3 based FETs have been summarized and compared, including planar/vertical metal-oxide-semiconductor field-effect transistor (MOSFET), trench MOSFET, FinFET, modulation-doped FET or called it high electron mobility transistors with two-dimensional electron gas channel, SOI MOSFET, thus the potential of Ga2O3 FETs is preliminary revealed. Finally, the prospect of the Ga2O3 based FET for high-power and RF application will be also analyzed.

Fully transparent ITO/LaAlO3/ITO structure RRAM (resistive random access memory) devices were fabricated on glass substrate, and ITO/Al2O3/ITO structure devices were set for comparison. The electrical characteristics of the devices were analyzed by Agilent B1500A semiconductor analyzer. Compared with the ITO/Al2O3/ITO RRAM devices, the current stability, SET/RESET voltage distribution, and retention characteristic of the ITO/LaAlO3/ITO RRAM devices have been greatly improved. In the visible light range, the light transmittance of the device is about 80%, that of the LaAlO3 layer is about 95%, the on-off ratio of the device is greater than 40, and the data retention time is longer than 10,000 s. The devices have great optical and electrical properties and have huge application potential as fully transparent RRAM devices.

A novel enhanced mode (E-mode) Ga2O3 metal–oxide–semiconductor field-effect transistor (MOSFET) with vertical FINFET structure is proposed and the characteristics of that device are numerically investigated. It is found that the concentration of the source region and the width coupled with the height of the channel mainly effect the on-state characteristics. The metal material of the gate, the oxide material, the oxide thickness, and the epitaxial layer concentration strongly affect the threshold voltage and the output currents. Enabling an E-mode MOSFET device requires a large work function gate metal and an oxide with large dielectric constant. When the output current density of the device increases, the source concentration, the thickness of the epitaxial layer, and the total width of the device need to be expanded. The threshold voltage decreases with the increase of the width of the channel area under the same gate voltage. It is indicated that a set of optimal parameters of a practical vertical enhancement-mode Ga2O3 MOSFET requires the epitaxial layer concentration, the channel height of the device, the thickness of the source region, and the oxide thickness of the device should be less than 5 × 1016 cm−3, less than 1.5 μm, between 0.1 μm − − 0.3 μm and less than 0.08 μm, respectively.

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