Anion vacancies in CuInSe2

Effects of the Cu2-xSe surface phase, the post-growth air-annealing and the Na incorporation on the growth and properties of CuInSe2, films have been systematically investigated by various defect-sensitive characterization te chniques such as low temperature photoluminescence and positron annihilatio n. The presence of the Cu-Se surface phase, the post-growth air-annealing a nd the Na incorporation all provided significant changes in photoluminescen ce spectra. Decrease in positron lifetime and reduction of twin density wer e found to occur simultaneously, along with the changes in photoluminescenc e spectra. Change in photoluminescence spectra and the corresponding decrea se in positron lifetime indicate the annihilation of Se-vacancies; the cont rol of Se-vacancy is a key issue to be addressed for improving the electric al, optical and structural properties of CuInSe2 films. (C) 2001 Elsevier S cience B,V. All rights reserved.