A comparative study of AlN and Al₂O₃ based gate stacks grown by atomic layer deposition on InGaAs Available to Purchase

Thermal activated atomic layer deposited (t) (ALD) and plasma enhanced (p) ALD (PEALD) AlN films were investigated for gate applications of InGaAs based metal-insulator-semiconductor devices and compared to the well-known Al₂O₃ based system. The roles of post-metallization annealing (PMA) and the pre-deposition treatment (PDT) by either trimethylaluminium (TMA) or NH₃ were studied. In contrast to the case of Al₂O₃, in the case of AlN, the annealing temperature reduced interface states density. In addition, improvement of the AlN film stoichiometry and a related border traps density reduction were observed following PMA. The lowest interface states density (among the investigated gate stacks) was found for PEALD AlN/InGaAs stacks after TMA PDT. At the same time, higher values of the dispersion in accumulation were observed for AlN/InGaAs gate stacks compared to those with Al₂O₃ dielectric. No indium out-diffusion and the related leakage current degradation due to annealing were observed at the AlN/InGaAs stack. In light of these findings, we conclude that AlN is a promising material for InGaAs based gate stack applications.