Interface quality improvement of metal/AlOxNy/AlGaN/GaN MIS-heterojunction by using alternative AlOxNy growth in PEALD system

Abstract

Aluminum oxynitride (AlOxNy) films with nitrogen content ranging from 2.51% to 6.38% were employed as gate dielectrics in GaN-based metal–insulator–semiconductor (MIS) structures. These films were deposited using a plasma-enhanced atomic layer deposition system through alternating cycles of AlN and Al2O3. X-ray photoelectron spectroscopy analysis of the Al 2p and N 1s peaks shows that the AlOxNy films contain Al–N, Al–O, and N–Al–O bonds, suggesting the appearance of ternary compound AlOxNy. Capacitance–voltage (C–V) measurements reveal that both fixed charge density (Nfix) and the interface trap density (Dit) in all AlOxNy samples are significantly lower than those in Al2O3 samples. Especially, with the increasing nitrogen compositions, the 6.38 N% AlON sample exhibits an exceptionally low Dit of ∼1011 cm−2eV−1. These results provide an effective approach to realizing more reliable and stable GaN-based MIS-high-electron-mobility transistors.