Observation of competing arsenic removal channels in the Cl2+GaAs reaction

Abstract

A molecular beam study of the Cl2+GaAs(s) reaction has been performed for surface temperatures in the range of 300–550 K. The gas phase neutral reaction products are identified by mass spectroscopy using electron bombardment ionization. Detailed analysis of the surface temperature dependence of the mass spectrum of the observed reaction products indicates that only three neutral reaction products are formed in this temperature range: GaCl3, AsCl3, and As4. At low (high) surface temperatures, only AsCl3 (As4) is observed. The ratio of the etching rates of Ga and As is independent of the surface temperature and within the range expected for stoichiometric etching. The change in the mode of As removal with surface temperature for the incident Cl2 flux implies that surface diffusion is important at surface temperatures above 400 K.