Charge trapping and carrier transport mechanism in silicon-rich silicon oxynitride

Abstract

The charge-trapping and carrier transport properties of silicon-rich silicon oxynitride (SRO:N) were studied. The SRO:N films were deposited by low pressure chemical vapor deposition. Infrared (IR) and transmission electron microscopic (TEM) measurements were performed to characterize their structural properties. Capacitance versus voltage and current versus voltage measurements (I–V) were used to study the charge-trapping and carrier transport mechanism. IR and TEM measurements revealed the existence of Si nanodots in SRO:N films. I–V measurements revealed that there are two conduction regimes divided by a threshold voltage VT. When the applied voltage is smaller than VT, the current is dominated by the charge transfer between the SRO:N and substrate; and in this regime only dynamic charging/discharging of the SRO:N layer is observed. When the voltage is larger than VT, the current increases rapidly and is dominated by the Poole–Frenkel mechanism; and in this regime, large permanent trapped charge density is obtained. Nitrogen incorporation significantly reduced the silicon nanodots or defects near the SRO:N/Si interface. However, a significant increase of the density of silicon nanodot in the bulk of the SRO:N layer is obtained.