Deposition of CuInS2 films by electrostatic field assisted ultrasonic spray pyrolysis

We studied CuInS2 (CIS) film growth using high electrostatic field assisted ultrasonic spray (HEFAUS) deposition. CIS films were fabricated with various precursors and substrate temperatures. All the as-sprayed CIS films were observed to be grown with mixed ordering mode, where chalcopyrite (CH) and CuAu (CA) orderings coexisted. It was found that application of additional sulfurization to sprayed CIS films induced re-crystallization of films accompanied by enhancement of CH ordering. After the post-sulfurization, the most improved film showed nearly the same CH-fraction as that for a CIS film which was made by sulfurization of sputtered Cu–In alloy film. These results indicate that our modified spray deposition could be used for fabrication of CIS photoabsorbing layer instead of high-cost vacuum-based process. All fabricated films were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscope and energy dispersive X-ray analysis measurements.