Transport in Silicon Nanowires: Role of Radial Dopant Profile

TL;DR

This study investigates how the radial distribution of phosphorus dopants affects electronic transport in silicon nanowires, revealing that surface doping enhances conductance and reduces fluctuations, with implications for device modeling.

Contribution

It combines ab initio DFT calculations with Green's function methods to analyze dopant distribution effects on silicon nanowire conductance.

Findings

Surface doped wires have longer mean-free paths.

Radial dopant distribution significantly influences conductance.

Simple models can predict scattering effects of dopants.

Abstract

We consider the electronic transport properties of phosphorus (P) doped silicon nanowires (SiNWs). By combining ab initio density functional theory (DFT) calculations with a recursive Green's function method, we calculate the conductance distribution of up to 200 nm long SiNWs with different distributions of P dopant impurities. We find that the radial distribution of the dopants influences the conductance properties significantly: Surface doped wires have longer mean-free paths and smaller sample-to-sample fluctuations in the cross-over from ballistic to diffusive transport. These findings can be quantitatively predicted in terms of the scattering properties of the single dopant atoms, implying that relatively simple calculations are sufficient in practical device modeling