Sub-Micron Gallium Oxide Radio Frequency Field-Effect Transistors

Beta-gallium oxide (BGO) radio frequency device performance is presented using sub-micron T-shaped gates. In the first design, a gate-recess is implemented to allow gate and channel device scaling which results in f_t/f_max= 3/13 GHz at VDS= 40 V. The second approach uses a thin and higher doped channel with a T-gate formed by electron beam lithography. An f_t/f_max= 5/17 GHz is measured at V_DS= 15 V and is the highest reported for BGO transistors. Significant gains in RF performance are expected with reduction of device parasitics and vertically scaled epitaxial designs.