Atomic layer epitaxy of GaP and elucidation for self-limiting mechanism

Abstract

Atomic layer epitaxy (ALE) of GaP was performed for the first time in a low-pressure metalorganic vapor phase epitaxial (MOVPE) reactor using trimethylgallium (TMG) and phosphine (PH3) as sources. Growth was self-limiting for the exposure time of each reactant. X-ray photoelectron spectroscopy (XPS) analyses were carried out to identify the adsorbates on the growth surface. There were no methyl groups on the surface Ga and the self-limiting mechanism is due to the selective adsorption of TMG by the surface P atoms. When the substrate was exposed to a sufficient TMG flow after a submonolayer Ga was deposited by triethylgallium (TEG), growth was still self-limiting. This supports the selective adsorption model.