Deposition of CZTS|ZnO Hetero-Junction Using SILAR and Spray Pyrolysis

Abstract

Copper zinc tin sulphide (CZTS) thin films have been deposited on glass substrate at 323 ± 5 K using sequential ionic layer adsorption reaction (SILAR). The number of SILAR cycles required for optimum crystalline quality CZTS thin films was optimized. The as-deposited CZTS thin films showed kesterite crystalline structure with preferential orientation along (103) plane. Structural, optical, electrical, and morphological properties of the films changed when the as-prepared films were subjected to annealing in a vacuum chamber maintained at 3 × 10–4 Torr at temperatures of 473, 573, and 673 K. Film resistivity was found to decrease exponentially as the annealing temperature was increased. We have achieved a resistivity of 4.4 × 10–4 Ω m for the as-prepared thin film, which is lowest among SILAR-grown films at temperature lower than 373 K without any post-deposition processing. A superstrate-type p–n junction was fabricated by growing nano-structured zinc oxide (ZnO) on top of the glass|CZTS structure using chemical spray pyrolysis technique. The photosensitivity of the p–n junction was reversed when the structure was subjected to vacuum annealing at 673 K.