Thermal and electron-induced reactions of AsCl3 on GaAs(100)

The adsorption and decomposition reactions of AsCl3 on the gallium-rich GaAs(100)-(4 x 1) surface have been investigated using Auger Electron spectroscopy (AES), Low Energy Electron Diffraction (LEED) and Temperature Programmed Desorption (TPD) techniques. At room temperature AsCl3 adsorbs molecularly. Thermal decomposition of the adsorbed AsCl3 occurs, to form adsorbed AsCl2 and CI, and this dissociation channel competes with its desorption into the gas phase. Principal desorption products were identified as AsCl3 (390K), AsCl2 (400K),GaCl (610K), As-2 (640K) and As-4 (640K). Electron irradiation of the adsorbed AsCl3 causes its dissociation and the process occurs with a reaction cross section of (2.2+/-0.3) x 10(-16) cm(2). This dissociation has the effect of bringing about large increases in the etch products GaCl, As-2 and As-4 A significant difference between thermal and electron-induced dissociation was that As-4 was found to become a major etch product following electron irradiation, and LEED shows the surface structure at these high As-4 concentrations corresponds to a c(4 x 4) reconstruction. In this paper eve discuss the thermal and electron induced decomposition mechanisms of AsCl3 on GaAs(100), and the implications that these reaction mechanisms may have in the use of AsCl3 in the chemical beam processing of compound semiconductors. (C) 1999 Elsevier Science B.V. All rights reserved.