Structural analysis of Cu1-xAgxGaSe2 bulk materials and thin films

The influence of the Ag-content in the quaternary compound Cu1-xAgxGaSe2 (0 less than or equal to x less than or equal to 0.38) on the structural prop erties of the bulk material and subsequently deposited thin films is discus sed. Cu1-xAgxGaSe2 bulk material was synthesized from the elements via a li quid phase reaction method. and thin films were subsequently deposited onto Mo-coated glass substrates by chemical vapor deposition (CVD) employing io dine as the transport agent, while hydrogen served as the carrier gas. X-ra y diffraction measurements of the bulk material showed that single phase Cu 1-xAgxGaSe2 could be obtained. For synthesis under iodine addition. AgI was found to be present in small amounts for x greater than or equal to 0.2. w hereas synthesis without iodine resulted in the formation of Cu1.8Se for x greater than or equal to 0.1. Examination of the lattice parameters reveale d an increase in alpha from 5.62 to 5.70 Angstrom with increasing x, while c remained approximately constant at 11.03 Angstrom. The results allow us t o refine and verify our previously proposed model of the effects of Ag-inco rporation into CuGaSe2. Thin films deposited from the above material at 480 and 520 degrees C showed identical XRD spectra with Ag2Se present for x gr eater than or equal to 0.2, while a detailed comparison of alpha and c to t he values of the bulk material is complicated due to the presence of the Ag 2Se phase. (C) 2000 Elsevier science S.A. All rights reserved.