Atomic-scale characterization of the N incorporation on GaAs(001)

Abstract

The initial nitridation processes of GaAs(001) have been systematically studied using reflection high-energy electron diffraction, scanning tunneling microscopy, and x-ray photoelectron spectroscopy. The structure and composition of the nitrided surface strongly depends on the preparation condition. The amount of N atoms decreases with increasing substrate temperature, which is due to the desorption of N at higher temperatures. The surface nitrided without As4 flux shows a N-induced (3 × 3) reconstruction tentatively associated with a N-N dimer formation at the surface layer. N incorporation is less promoted when the initial GaAs surface is exposed to active N species under the As4 flux, because of the replacement of N atoms by the arriving As atoms. We found that N atoms are initially incorporated in the substitutional site at the central position below two As-As dimers in the β2(2 × 4) structure.