Investigation of E-Mode Beta-Gallium Oxide MOSFET for Emerging Nanoelectronics

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Abstract
Gallium Oxide (Ga 2 O 3 ) is an emerging material due to its suitable material properties and device characteristics. N-type Ga 2 O 3 layer grown on semi-insulating Ga 2 O 3 substrate results in depletion-mode MOSFET-an always ‘on' device with negative threshold voltage. In absence of p-type doping in Ga 2 O 3 ; 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 Ga 2 O 3 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 10 10 . 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 Ga 2 O 3 material processing technologies can potentially achieve high performance power electronic devices.

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