Origins of GaN(0 0 0 1) surface reconstructions

TL;DR

This study investigates the surface reconstructions of GaN(0 0 0 1) with and without arsenic using in situ RHEED and STM, revealing specific reconstruction patterns and clarifying arsenic's role in these processes.

Contribution

It provides new insights into the surface reconstructions of GaN(0 0 0 1) and clarifies arsenic's influence using multiple experimental techniques.

Findings

Identification of various surface reconstructions via RHEED.

Only some reconstructions show long-range order in STM.

Arsenic's role in GaN surface reconstruction is clarified.

Abstract

The reconstructions of the Ga polarity GaN(0 0 0 1) surface with and without trace amounts of arsenic and prepared by molecular beam epitaxy (MBE) have been studied with in situ reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). Various reconstructions are observed with RHEED by analyzing patterns while the substrate is exposed to a fixed NH3 flux or after depositing known amounts of Ga as a function of substrate temperature. In situ STM images reveal that only a few of these reconstructions yield long-range periodicity in real space. The controversial role of arsenic on Ga induced reconstructions was also investigated using two independent MBE chambers and X-ray photoelectron spectroscopy.