Time-resolved carrier tunneling in nanocrystalline silicon/amorphous silicon dioxide superlattices

Eight period nanocrystalline Si/amorphous SiO2 superlattices with Si nanocrystals of similar to5 nm diameter and tunnel-transparent (1.6-1.8-nm-thick) layers of SiO2 reveal a sharp resonance in conductivity at a low (similar to0.8 V) applied bias. The performed measurements of time-resolved photocurrent decay show two distinctly different components. A fast, temperature-independent decay dominates at the applied bias close to the resonant conditions. Slower, temperature-dependent photocurrent decay becomes dominant at higher (>1.5 V) voltages. The observed fast photocurrent transient is associated with resonant hole tunneling throughout nanocrystalline Si superlattices. (C) 2003 American Institute of Physics.