Investigation of E-Mode beta-gallium oxide MOSFET for emerging nanoelectronics

Gallium Oxide (Ga₂O₃) is an emerging material due to its suitable material properties and device characteristics. N-type Ga₂O₃ layer grown on semi-insulating Ga₂O₃ substrate results in depletion-mode MOSFET-an always 'on' device with negative threshold voltage. In absence of p-type doping in Ga₂O₃; conducting channel is available at V_GS = 0V, however, for high voltage and power applications enhancement-mode (e-mode) transistors find more suitability. Hence, in this paper an e-mode 'T' shaped recessed gate novel Ga₂O₃ MOSFET (E-MOSFET) is designed and simulated using Atlas TCAD. The 'T' shape recessed gate depletes major portion of the active channel region and thus ensures off-operation at zero gate bias. The device achieves V_Th of 0.05 V, and on-resistance (R_on) of 212 Ω-mm. The simulated device results in peak drain current density (ID_max) of around 40 mA/mm and I_ON/I_OFF ratio greater than 10¹⁰. The device with source to drain spacing of 20μm achieved subthreshold swing (SS) of 123 mV/dec which is the best reported value and in good agreement with experimental results. Effects of gate length variation on device key-parameters such as R_ON and V_Th are analyzed for optimum device performance; self-heating in the device at high voltages and resulting effects on device performance have been presented through extensive simulations. The device developments along with Ga₂O₃ material processing technologies can potentially achieve high performance power electronic devices.