Adsorption and Decomposition of Organometallics on GaAs Surfaces in Low-Pressure Metalorganic Chemical Vapor Deposition

Abstract

To determine the mechanism of surface reactions during metalorganic chemical vapor deposition, we perform mass spectrometric studies of the products desorbed from a GaAs surface upon pulsed supply of the reactants. We find that the surface after trimethylgallium (TMG) exposure is terminated by CH3 and that the desorption of the CH3 from the surface is activated by the presence of As. The adsorption of triethylgallium (TEG) is inhibited on a CH3-terminated surface whereas TEG is decomposed both on As-rich and on Ga-rich surfaces. The effect of CH3 termination is highlighted by the complete inhibition of triethylaluminum decomposition when it is introduced together with TMG.