Singular response to a dopant of an evaporating crystal surface

TL;DR

This paper demonstrates analytically that even a tiny amount of dopant can invert the stability of a moving crystal surface under electric current, explaining experimental observations of singular responses to gold doping on evaporating silicon surfaces.

Contribution

It provides an analytical explanation for the singular stability response of evaporating crystal surfaces to infinitesimal dopant quantities, linking it to inhomogeneous diffusion effects.

Findings

Infinitesimal dopant quantities can invert surface stability.

Dopant density distribution relates to inhomogeneous silicon diffusion.

Explains experimental singular responses to gold doping.

Abstract

Moving crystal surfaces can undergo step-bunching instabilities, when subject to an electric current. We show analytically that an infinitesimal quantity of a dopant may invert the stability, whatever the sign of the current. Our study is relevant for experimental results [S. S. Kosolobov et al., JETP Lett. 81, 117 (2005)] on an evaporating Si(111) surface, which show a singular response to Au doping, whose density distribution is related to inhomogeneous Si diffusion.