Effect of annealing on structural and optical properties of Cu2ZnSnS4 thin films grown by pulsed laser deposition

• Cu2ZnSnS4 (CZTS) thin films were grown at room temperature.
• Reactive Pulsed Laser Deposition in H2S flow was used as a growth method.
• Effect of annealing conditions on CZTS structural and optical properties is revealed.
• Both the grain size and the band gap of CZTS film increase following the annealing.
• Annealing in N2 effectively inhibits the formation of SnxS secondary phases.

In this work, we compare the effect of different types of thermal annealing on the morphological, structural and optical properties of Cu2ZnSnS4 (CZTS) thin films grown by reactive Pulsed Laser Deposition in H2S flow. Rutherford backscattering spectrometry, atomic force microscopy, X-ray diffraction, Raman spectroscopy and optical spectrophotometry data reveal dramatic increase of the band gap and the crystallite size without the formation of secondary phases upon annealing in N2 at the optimized conditions.