CHARACTERIZATION OF CUINS2 THIN-FILMS GROWN BY CLOSE-SPACED VAPOR SULFURIZATION OF CO-SPUTTERED CU-IN ALLOY PRECURSORS

Cu-In alloy films were prepared on base or Mo-coated glass by co-sputt ering from Cu and In targets at ambient temperature. The formation of CuInS2 films was accomplished by sulfurization within a graphite conta iner under high S vapor pressure. X-ray diffraction (XRD) analysis of the alloy films showed predominant variation of the phases from In-->C uIn2-->Cu11In9 as the Cu content in the films increased. The sulfurize d In-rich films formed the CuIn5S8 phase that steadily transformed int o CuInS2 as film composition changed toward the Cu-rich region. SEM an alysis showed different morphologies for the CuIn5S8 and CuInS2 films. Cu-rich films exhibited very dense crystal structures. EDX compositio n measurements on the films showed Cu/(Cu + In) varying from 0.21 to 0 .64 and S/(Cu + In) from 0.80 to 1.36. Resistivities in the range of 2 .36 to 1.7 x 10(8) Ohm. cm were obtained. Studies of the growth mechan ism indicated formation of CuIn5S8 as the main secondary phase in both Cu-rich and In-rich films at low temperatures before conversion into CuInS2 at temperatures >400 degrees C.