In-situ nitrogen plasma passivation of Al2O3/GaN interface states

The authors report on in-situ nitrogen plasma cleaning, consisting of alternating cycles of nitrogen plasma and trimethylaluminum prior to the dielectric deposition, as an effective method to passivate Al2O3/GaN interface states. The nitrogen plasma pretreatment reduces the frequency dispersion in capacitance–voltage and the conductance peak in conductance–voltage measurements, compared to interfaces cleaned with a hydrogen plasma pretreatment. It is shown that the decrease of the trap density (Dit) below the conduction band is correlated with the suppression of Ga-O bonding and the formation of an aluminum oxynitride interfacial layer.