Thin films of CuInSe2and CuGaSe2were grown by molecular‐beam epitaxy. Domain structures in these films were examined by transmission electron microscopy. We demonstrate that orientation domains may not form by the use of (001)GaAs substrate while antiphase domains can be eliminated by annealing the films in the presence of a Se beam. The annealing temperatures were 400 °C for CuInSe2and 450 °C for CuGaSe2. Photoluminescence measurements on an annealed CuInSe2film exhibited a decrease in intensity of optical emissions associated with antisite defects and an enhancement in near‐band‐edge emission intensity. ©1996 American Institute of Physics.