Development of an automated ultrasonic spray pyrolysis system and the growth of Cu2ZnSnS4 thin films

• Developed an automated ultrasonic spray pyrolysis system.
• It provides facilities for x–y movement and 300 × 300 mm area of deposition.
• Kesterite structured Cu2ZnSnS4 films were grown using this.
• Single phase p-type films were obtained after optimization.

An automated ultrasonic spray pyrolysis system is fabricated for the growth of thin films. The system is equipped with x–y movement and enables film deposition in different patterns and spray rates. Cu2(Zn,Sn)S4 (CZTS) films are deposited using this setup. The substrate temperature (Ts) is varied from 240 to 490 °C. Kesterite CZTS phase is observed in all the films together with binary phases. The films prepared at Ts < 340 °C showed SnxSy phase and those at Ts > 340 °C showed Cu2S phase. Sulfur incorporation is maximum (40%) at 440 °C and the films showed better morphology. The Cu and S concentrations are varied to remove binary phases. Depth wise elemental analysis confirmed the existence of single phase CZTS. p-Type CZTS films of resistivity in the range of 102–103 Ωcm are obtained.