Effect of surface polarity on gallium adsorption on 6H-SiC surfaces

Abstract

We have performed the first scanning tunneling microscopy (STM) study of gallium adsorption on both the Si-terminated 6H-SiC(0001) (∛×∛) and C-terminated 6H-SiC(0001̄) (2∛×2∛) surfaces. The structure of the Ga terminated 6H-SiC surface showed strong polarity dependence. On the Si-terminated ∛×∛ surface, parallel rows of Ga atoms arranged in three different domains oriented at 120° with respect to each other at 1 ML coverage were observed. On the C-terminated 2∛×2∛ surface, sets of two concentric rings formed an overall 4∛×4∛ reconstruction at 1 ML coverage. We propose a structural model for the 4∛×4∛ structure which explains the STM image.