Surface passivation of n-GaN by nitrided-thin-Ga2O3/SiO2 and Si3N4 films

The electrical characteristics of n-GaN/nitrided-thin-Ga2O3/SiO2 and n-GaN/Si3N4 metal-insulator-semiconductor (MIS) capacitors have been compared, and the work-function difference phi(ms) and effective dielectric-fixed charge density Q(f,eff) have been determined. Oxide samples showed lower interface trap level density D-it, lower leakage current, and better reproducibility compared to the nitride samples. The superior properties of the oxide samples are partially attributed to the nitrided-thin-Ga2O3 layer (similar to0.6-nm-thick). phi(ms) and Q(f,eff) were determined, respectively, as 0.13 V and 1.0x10(12) q cm(-2) in oxide and 0.27 V and -3.6x10(11) q cm(-2) in nitride samples using flatband voltage versus dielectric thickness data. True dielectric-fixed charge density and location of the major amount of fixed charge are discussed based on Q(f,eff), D-it, and spontaneous polarization of n-GaN. (C) 2004 American Institute of Physics.