What causes Poole-Frenkel transport in VLS grown silicon nanowires?

Abstract

It is already established that Poole-Frenkel (PF) transport is the dominant method of current transport in gold-catalyzed, Vapor-Liquid-Solid (VLS) grown, intrinsic silicon nanowires. However, this is contrary to common knowledge in the field. PF transport is often used to model the current-voltage (IV) relationship of materials without long-range order. In this study, the physical nature of the coulomb traps responsible for PF transport in VLS grown silicon nanowires has been investigated. It has been found that, VLS grown, single crystal silicon nanowires have small regions (<25 nm2) of crystallographic misorientation throughout their volume. This, along with the twin boundaries found in the analysis, can periodically trap and detrap charge carriers traversing between the metal contacts on silicon nanowires. It is proposed that the omnipresence of these defects in the channel region to be the origin of PF transport in VLS grown silicon nanowires.