Electron-beam enhanced creep deformation of amorphous silicon nano-cantilever

Abstract

To investigate the creep properties of amorphous silicon (a-Si) nanocantilevers and the effects of electron beam (EB) irradiation on those properties, we performed creep bending experiments with and without EB irradiation using field emission scanning electron microscopy at room temperature. Approximately 220 nm-thick a-Si nanocantilevers were fabricated with controlled shape and size by substrate shape-assisted glancing angle deposition. The results showed that EB irradiation increased fracture strength and greatly enhanced creep deformation of a-Si nanocantilevers. Under EB irradiation, a-Si nanocantilevers showed continuous creep behavior consisting of transition, steady-state, and redeceleration regions, while creep deformation was brought about with intermittent displacement bursts under nonirradiation. EB irradiation resulted in the decrease of the creep exponent n, from n=5.55 under nonirradiation to n=2.46 under EB irradiation, indicating a change in the creep mechanism. Creep resistance was restored by halting EB irradiation, which indicates that the change in creep properties was only temporary. This suggests that the mechanical properties of a-Si nanostructures, such as creep characteristics, can be temporarily altered by EB irradiation.