Comparison of point defects in CuInSe2 and CuGaSe2 single crystals

Hall-effect and photoluminescence measurements have been carried out on as-grown and In/Ga-annealed CuInSe2 and CuGaSe2 single crystals grown by chemical vapor transport. Various defect levels in these related compounds have been identified and compared. V-Cu and Vs, show similar properties and activation energies in both materials. A tremendous difference is observed in the behavior of IIICu antisite defects. Ga-Cu levels in CuGaSe2 are much deeper than In-Cu in CuInSe2, and furthermore, the formation of In-Cu is much easier compared to Ga-Cu. This is related to the higher formation energy of Ga-Cu in CuGaSe2. Due to this difference in the defect chemistry of both compounds, it has not been possible until now, to prepare n-type CuGaSe2 crystals, whereas CuInSe2 is easily transformed from p- to n-type by annealing in vacuum or In-atmosphere. (C) 1999 Published by Elsevier Science B.V. All rights reserved.