Type and formation mechanism of thermal etch pits on annealed (111) CdZnTe surface were studied with scanning electron microscopy and atomic force microscopy. Four kinds of thermal etch pits on CdZnTe (111) Te face and two kinds of thermal etch pits on (111) Cd face were identified. The density of thermal etch pits on (111) Te face was estimated; it was two orders of magnitude higher than that of (111) Cd face. A formation mechanism of the thermal etch pits on (111) CdZnTe during the annealing process is proposed. The different behaviors of the thermal etch pits on the two faces of (111) CdZnTe are discussed. (C) 2008 Elsevier B.V. All rights reserved.