Silver (Ag) incorporated Cu2ZnSnS4 thin film for improved optical and morphological properties

Abstract

Replacing copper (Cu) with silver (Ag) which is always in monovalent state can improve the stability and quality of Cu2ZnSnS4 (CZTS). In this work, few copper (Cu) atoms have been substituted by Ag into the crystal lattice of CZTS by Ag deposition using DC (direct current) magnetron sputtering before stacked layer reactively sputtered individual Sn-Cu-Zn targets at room temperature and post annealed at 550 degrees C for 5 min only. Substitution of Cu with Ag reduces antisite defects, secondary phases and also improves the optical absorbance and grain size of the (Ag,Cu)(2)ZnSnS4 (ACZTS) thin film. Rice-like structured ACZTS film showed optical absorption coefficient one order of magnitude higher than CZTS thin film. The band gap was slightly smaller 1.4 eV for ACZTS as compared to 1.5 eV for CZTS film. To the best of our acquaintance, this is the first study on synthesis of rice-like structured ACZTS film and investigation of optical and morphological properties. Also the method used for sample preparation (sputtering) with short annealing time can be an industrially viable technique