In-situ reflectance monitoring of GaSb substrate oxide desorption

The use of specular reflectance to monitor GaSb substrate oxide desorption in-situ is reported. Substrates were loaded into the organometallic vapor p hase epitaxy reactor either as-received (epi-ready) or after receiving a so lvent degrease, acid etch and rinse. A variety of surface preparations and anneal conditions win investigated. HCl was used as the etchant, and in cer tain cases was followed by an additional etch in Br-2-HCl-HNO3-Ch(3)COOH fo r comparison. Rinse comparisons included 2-propanol, methanol, and deionize d water. Substrates were heated to either 525 degreesC, 550 degreesC, or 57 5 degreesC. Features observed in the in-situ reflectance associated with th e oxide desorption process are interpreted based on the starting oxide chem istry and thickness. Based on in-situ reflectance and ex-situ atomic force microscopy data, a recommendation on a reproducible GaSb substrate preparat ion technique suitable for high-quality epitaxial growth is suggested. (C) 2001 Elsevier Science B.V. All rights reserved.