Investigation of critical barrier thickness in lattice matched InAlN/GaN MOSHEMT towards normally-off operation

An ultrathin normally-off lattice matched In0.17Al0.83N/GaN metal oxide semiconductor high electron mobility transistor is proposed. Analytical model for two-dimensional electron gas density has been developed to investigate the critical thickness of InAlN barrier. Numerical simulations have been performed using SILVACO TCAD to justify that the critical barrier thickness is 8nm for inducing the two-dimensional electron gas. A sub-critical 3nm thick barrier device is simulated and a positive threshold voltage of 1V is realized at 10nm oxide (Al2O3) thickness. The transconductance and drain characteristics are also studied in order to verify the feasibility of the device. The proposed device can overcome the lacuna of enhancement mode GaN based devices in power electronic applications.