SiN<inf>x</inf> passivated GaN HEMT by plasma enhanced atomic layer deposition

Abstract

Plasma enhanced atomic layer deposited (PEALD) films of SiN x and Al 2 O 3 have been investigated for surface passivation of AlGaN/GaN high electron mobility transistors (HEMTs). Through DC characterization of the fabricated HEMTs with the 3 nm thick films, the SiNx passivated HEMT showed the lowest on-resistance (R on ) of 6.7 Ω · mm. Since channel resistances under the gate electrodes and Ohmic contact resistances are identical to all the samples due to the same lots of fabrication, the lowest R on is ascribed to the reduced channel resistance between gate and Ohmic electrodes where the film was deposited, i.e. an increase in the electron concentration at the channel region. This increase suggests lowering of the electron potential at the surface, and the lowering would be ascribed to a decrease in surface traps with electrons captured. Consequently, this implies that dangling bonds of the HEMT surface are well terminated by PEALD-SiN x .