Evidence of hole flow in silicon nitride for positive gate voltage

This paper discusses the conduction mechanism of silicon nitride. n-channel transistors and MOS capacitors with the top-oxide/ nitride/bottom-oxide dielectric structure were used to characterize the dielectric conduction. Top and bottom oxides were found to have different effects on the dielectric leakage current and electron and hole tunneling. This implies that the dominant charge carriers across the top and bottom oxides are different. We claim the conduction through a bottom oxide is dominated by electron flow and conduction through a top oxide and the nitride is dominated by hole flow for positive gate voltage. Energy band diagrams are presented to discuss the effective trap level for hole conduction in the nitride and holes and electrons tunneling through the oxide/nitride/oxide dielectrics.