Sol-gel prepared Cu2ZnSnS4 (CZTS) semiconductor thin films: Role of solvent removal processing temperature

The conditions under which thin films are deposited are the most important parameter determining the physical performance of devices. In this work, we present the effect of preheating temperatures under N2 ambient conditions on the quality of Cu2ZnSnS4 (CZTS) thin films. Herein we are interested in the structural, morphological, vibrational, optical and electrical characteristics of CZTS layers, synthesized using the sol-gel method. CZTS layers were deposited at preheating temperatures of 200 °C, 250 °C and 300 °C under N2 ambient atmosphere prior to a 1-h sulphuration process at 580 °C. XRD results confirm the dependence of the crystallite size on temperature. All the deposited layers are in stannite phase, confirmed by Raman spectroscopy, and the electrical properties show that all films obtained are p-type semiconductors with a carrier charge concentration of 4.06–9.48 × 1020 cm−3. CZTS films preheated at 300 °C show better crystallinity, larger grains, more suitable band gap, higher electrical conductivity and improved surface morphology compared to the rest of the thin films, which indicates that the method proposed here can be used to deposited high quality absorber layers of CZTS for solar cells applications.