Growth optimization of unintentionally doped GaSb buffer layers on (1 0 0) GaSb substrates by molecular beam epitaxy is reported. Several growth parameters were varied to determine the optimal oxide desorption and GaSb growth conditions, as well as to investigate the conditions under which antimony condenses on the wafer surface. Variation of group-V stabilization flux level, timing of flux application during wafer heating and cooling, desorption anneal temperature, and GaSb growth temperature were investigated. Epilayer quality was gauged by optical microscopy, atomic force microscopy, 77 K photoluminescence, and X-ray photoelectrom spectroscopy. Results indicate that growth of GaSb at 520 degrees C, the highest temperature used here, combined with appropriate heating and cooling steps produces the highest quality bulk GaSb. (C) 2009 Elsevier B.V. All rights reserved.