Step bunching of vicinal 6H-SiC{0001} surfaces

TL;DR

This study uses kinetic Monte Carlo simulations to investigate how growth and etching cause step bunching on vicinal 6H-SiC{0001} surfaces, revealing different surface terminations depending on the process.

Contribution

The paper introduces a simulation approach that accounts for surface diffusion rates and step mobilities to reproduce experimental step bunching phenomena in 6H-SiC surfaces.

Findings

Single bilayer steps bunch into half unit cell height steps.

Adjacent half unit cell steps bunch into full unit cell height steps.

Growth and etching lead to different surface terminations.

Abstract

We use kinetic Monte Carlo simulations to understand growth- and etching-induced step bunching of 6H-SiC{0001} vicinal surfaces oriented towards [1-100] and [11-20]. By taking account of the different rates of surface diffusion on three inequivalent terraces, we reproduce the experimentally observed tendency for single bilayer height steps to bunch into half unit cell height steps. By taking account of the different mobilities of steps with different structures, we reproduce the experimentally observed tendency for adjacent pairs of half unit cell height steps to bunch into full unit cell height steps. A prediction of our simulations is that growth-induced and etching-induced step bunching lead to different surface terminations for the exposed terraces when full unit cell height steps are present.