A giant, anomalous piezo-response of fully-depleted silicon-on-insulator (FD-SOI) devices under mechanical stress is demonstrated using impedance spectroscopy. This piezo-response strongly depends on the measurement frequency, ω, and consists of both a piezoresistance (PZR) and piezocapacitance whose maximum values are πR=−1100×10−11 Pa−1 and πC=−900×10−11 Pa−1 respectively. These values should be compared with the usual bulk PZR in p-type silicon, πR=70×10−11 Pa−1. The observations are well described using models of space charge limited electron and hole currents in the presence of fast electronic traps having stress-dependent capture (ωc) and emission rates. Under steady-state conditions (i.e. when ω≪ωc) where the impedance spectroscopy measurements yield results that are directly comparable with previously published reports of PZR in depleted, silicon nano-objects, the overall piezo-response is just the usual, bulk silicon PZR. Anomalous PZR is observed only under non-steady-state conditions when ω≈ωc, with a symmetry suggesting that the electro-mechanically active fast traps are native Pb0 interface defects. The observations suggest new functionalities for FD-SOI, and shed light on the debate over the PZR of carrier depleted nano-silicon.
@article{arxiv.1801.09494,
title = {Giant, anomalous piezo-impedance of silicon-on-insulator},
author = {Heng Li and Christopher Tao-Kuan Lew and Brett Johnson and Jeffrey McCallum and Steve Arscott and Alistair Rowe},
journal= {arXiv preprint arXiv:1801.09494},
year = {2019}
}