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

In this paper, we propose a novel junction-less Ga2O3 metal-insulator-semiconductor field effect transistor (MISFET) with a p-GaN gate, named p-GaN Ga2O3-MISFET. A heavily doped thin layer p-GaN is set in the trench gate region to deeply deplete the n-Ga2O3 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 & mu;m to 0.5 & mu;m, the V (TH) of the p-GaN Ga2O3-MISFET varies from 3.2 V to 2.4 V with n (int) = -1 x 10(11) cm(-2), which is always about 2.2 V higher than those of conventional junction-less Ga2O3 MISFETs (CJL-MISFET). In addition, the BV of the CJL-MISFET decreases from & SIM;3400 V to & SIM;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 x 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 x 10(13) cm(-2) to 2 x 10(13) cm(-2)) at the p-GaN/Al2O3 interface.

Automated summary

In this paper, a novel junction-less Ga2O3 MISFET with a p-GaN gate is proposed. By setting a heavily doped thin layer p-GaN in the trench gate region, the n-Ga2O3 channel region can be deeply depleted, leading to a high threshold voltage and breakdown voltage. Analytical modeling and TCAD simulations show that the proposed MISFET exhibits a higher threshold voltage than conventional junction-less Ga2O3 MISFETs. Additionally, the breakdown voltage of the proposed MISFET is higher than that of conventional junction-less Ga2O3 MISFETs due to the enhanced electric field at the corner of the trench gate.