Resonant tunneling in partially disordered silicon nanostructures

Low-temperature vertical carrier transport in layered structures comprised of Si nanocrystals separated in the growth direction by angstrom-thick SiO2 layers exhibits entirely unexpected, well-defined resonances in conductivi ty. An unusual alternating current ( ac) conductivity dependence on frequen cy and low magnetic field, negative differential conductivity, reproducible N-shaped switching and self-oscillations were observed consistently. The m odeled conductivity mechanism is associated with resonant hole tunneling vi a quantized valence band states of Si nanocrystals. Tight-binding calculati ons of the quantum confinement effect for different Si nanocrystal sizes an d shapes strongly support the tunneling model.