Analytical model and simulation study of a novel enhancement-mode Ga2O3 MISFET realized by p-GaN gate

Abstract In this paper, we propose a novel junction-less Ga 2 O 3 metal–insulator–semiconductor field effect transistor (MISFET) with a p -GaN gate, named p -GaN Ga 2 O 3 -MISFET. A heavily doped thin layer p -GaN is set in the trench gate region to deeply deplete the n -Ga 2 O 3 channel region owing to the high work function of the p -GaN. Thus, a high threshold voltage ( V TH ) and breakdown voltage (BV) can be obtained even with a wide-fin design and low interface charge density ( n int ), which ensures easy fabrication and a stable V TH . Analytical modeling and experimentally calibrated technology computer aided design (TCAD) simulations confirm that with the increase of fin width ( W Fin ) from 0.1 μ m to 0.5 μ m, the V TH of the p -GaN Ga 2 O 3 -MISFET varies from 3.2 V to 2.4 V with n int = −1 × 10 11 cm −2 , which is always about 2.2 V higher than those of conventional junction-less Ga 2 O 3 MISFETs (CJL-MISFET). In addition, the BV of the CJL-MISFET decreases from ∼3400 V to ∼45 V with increasing W Fin due to soft breakdown, while the BV of the p -GaN MISFET only decreases to 2800 V due to the enhanced electric field at the corner of the trench gate. Moreover, the activation energy and doping concentration (when larger than 3 × 10 19 cm −3 ) of p -GaN barely affect the V TH . Even so, a high V TH remained in a common range of interface charge (from 1 × 10 13 cm −2 to 2 × 10 13 cm −2 ) at the p -GaN/Al 2 O 3 interface.