Etching of GaAs by CCl4 and VCl4 in a metalorganic vapor-phase epitaxy reactor

In situ etching of GaAs, AIAs and carbon-doped GaAs layers by CCl4 prior to growth was monitored by reflectometry with a 632.8 nm laser beam. A comparison between growth and etching rates of GaAs and carbon-doped GaAs, indicates that the reduction in the growth rate usually observed in heavily carbon-doped GaAs using CCl4 should be attributed to the Ga reduction by the formation of GaCl4 (x = 1-3) species in the gas and solid phases. We investigated the etching of the GaAs epitaxial layer or substrate by CCl4 or VCl4 gas inside a metalorganic vapor-phase epitaxy (MOVPE) reactor at various temperatures and under different flow rates of CCl4 or VCl4. The evolution of the reflectometry signal gives qualitative informations on the etched surface. A smooth etched surface can be achieved at high temperatures for both tetrachlorides. (C) 1998 Published by Elsevier Science B.V. All rights reserved.