Characteristics of Cu₂ZnSnS₄ Thin Films Fabricated by Sulfurization of Two Stacked Metallic Layers

Abstract

A Cu₂ZnSnS₄ (CZTS) film was fabricated by sulfurization of two stacked layers of Cu (Zn, Sn) (CZT) alloy precursors. The sulfurization was performed in an evacuated and sealed quartz ampoule with sulfur powder, in which samples were annealed at 450°C, 500°C, or 550°C for 1 h and then allowed to cool naturally. The XRD patterns of all samples are well matched to those of the CZTS crystal. In this study, it is confirmed that the Sn in the metal precursors is lost in the form of SnS gas and a SnS₂ solid that crystallizes upon the combination of SnS and S when the CZTS film is annealed. The band gap energy of CZTS absorber was determined to be 1.370–1.414 eV. The surface morphology and grain shapes of these CZTS thin films were analyzed using SEM images and XRD patterns.

Keywords:

• CZTS
• Cu₂ZnSnS₄
• solar cell
• band gap energy
• sulfurization
• photovoltaics

Funding

This study was supported by the Daegu University Research Grant, 2013.