SILICON-NITRIDE SEMICONDUCTOR INTERFACE STATE DENSITY AS A FUNCTION OF THE INSULATOR STOICHIOMETRY

The interface state density and the fixed charge were measured on metal/insulator/semiconductor (MIS) structures produced using plasma-enhanced chemical vapour deposited silicon nitride as insulator layer and Si, InGaAs and InGaAsP as semiconductors. The experimental results showed that the electrical characteristics of the interface depends on both the insulator stoichiometry, varied by changing the values of the insulator deposition parameters, and the physical conditions of the semiconductor surface. The plasma-induced damage in the surface layer of the compound semiconductors was found to be responsible of the U-shaped interface state density distributions, in agreement with the "surface disorder model" postulated for the GaAs and InP interfaces. The decrease of the density of states and the fixed charge, induced by a thermal annealing in nitrogen, is also shown and discussed.