The growth of nanostructured Cu2ZnSnS4 films by pulsed laser deposition

In this work, we investigated on the growth of Cu2ZnSnS4 films by using pulsed Nd:YAG laser (355 nm) ablation of a quaternary Cu2ZnSnS4 target. Depositions were performed at laser fluence from 0.5 to 4 J cm−2. The films were grown at substrate temperature from 27 °C to 300 °C onto glass and silicon substrates. The dependence of the film morphology, composition, and optical properties are studied and discussed with respect to laser fluence and substrate temperature. Composition analysis from energy dispersive X-ray spectral results show that CZTS films with composition near stoichiometric were obtained at an optimized fluence at 2 J cm−2 by 355 nm laser where the absorption coefficient is >104 cm−1, and optical band gap from a Tauc plot was ∼1.9 eV. At high fluence, Cu and Sn rich droplets were detected which affect the overall quality of the films. The presence of the droplets was associated to the high degree of preferential and subsurface melting on the target during high fluence laser ablation. Crystallinity and optical band gap (1.5 eV) were improved when deposition was performed at substrate temperature of 100 °C.