ABSTRACT
Intrinsic defects in molecular-beam-epitaxy grown CuInSe2 films have been studied by positron annihilation spectroscopy coupled with monoenergetic positron beams. Both the S-parameter of Doppler-broadening measurement and positron lifetime of In-rich CuInSes films are significantly higher than those of Cu-rich films. These results suggest that there exists a high density of vacancy type defects in In-rich films. From a theoretical calculation, the lifetime component of In-rich films can be attributed to divacncies of Cu and Se atoms. After In-rich films were annealed in air, significant decrease in both positron lifetime and S-parameter was found. This suggests oxygen atoms substitute for the selenium vacancy of V(CuSe).
