In order to clarify the physics of the gating of solids by ionic liquids (ILs) we have gated lightly doped p-Si, which is so well studied that it can be called the "hydrogen atom of solid state physics" and can be used as a test bed for ionic liquids. We explore the case where the concentration of induced holes at the Si surface is below 1012cm−2, hundreds of times smaller than record values. We find that in this case an excess negative ion binds a hole on the interface between the IL and Si becoming a surface acceptor. We study the surface conductance of holes hopping between such nearest neighbor acceptors. Analyzing the acceptor concentration dependence of this conductivity, we find that the localization length of a hole is in reasonable agreement with our direct variational calculation of its binding energy. The observed hopping conductivity resembles that of well studied Na+ implanted Si MOSFETs.
@article{arxiv.1505.00065,
title = {Hopping Conduction via Ionic Liquid Induced Silicon Surface States},
author = {J. Nelson and K. V. Reich and M. Sammon and B. I. Shklovskii and A. M. Goldman},
journal= {arXiv preprint arXiv:1505.00065},
year = {2015}
}