Atomically straight steps on vicinal Si (111) surfaces prepared by step-parallel current in the kink-up direction

TL;DR

This study shows that applying a step-parallel current in the kink-up direction during annealing creates atomically straight Si(111) steps, with potential for nanostructure templating, explained by electromigration effects.

Contribution

It introduces a method to produce atomically straight Si(111) steps using current direction during annealing, supported by a phenomenological electromigration model.

Findings

Straight steps formed only with kink-up current

All steps exhibit the same atomic configuration U(2,0)

Electromigration explains current-polarity dependence

Abstract

We demonstrate that annealing of a vicinal Si(111) surface at about 800 C with a direct current in the direction that ascends the kinks enhances the formation of atomically straight step edges over micrometer lengths, while annealing with a current in the opposite direction does not. Every straight step edge has the same atomic configuration U(2,0), which is useful as a template for the formation of a variety of nanostructures. A phenomenological model based on electromigration of charged mobile atoms explains the observed current-polarity dependent behavior.