Annealing Time Dependence of Crystallization in Cu₂ZnSnSe₄Films

Abstract

Cu₂ZnSnSe₄(CZTSe) films were formulated by the selenization of Cu(Zn, Sn) (CZT) metal precursors. The CZT precursor was prepared by depositing zinc onto a Cu-Sn layer co-sputtered on molybdenum-coated soda-lime glass substrates. Selenium was evaporated thermally onto the CZT precursor. The resulting CZTSe film was then annealed at 450 °C for various annealing times (1, 3, 5, 10 and 15 min) using a rapid thermal process (RTP). Crystallization of the CZTSe film as a function of the annealing time was observed by X-ray diffraction (XRD). The XRD patterns of the films annealed over 3 min were well matched to those of a CZTSe single crystal. The lattice parameters of the CZTSe films annealed over 5 min were a = 5.639 Å and c = 11.356 Å. These values were reasonably close to the lattice parameters of a single crystal of Cu₂ZnSnSe₄(a = 5.693 Å and c = 11.333 Å). The energy gap of the CZTSe films was 1.14 eV.

Keywords:

• Band gap energy
• crystallization
• CZTSe
• RTP
• selenization
• solar cell

Acknowledgment

This study was supported by the Daegu University Research Grant, 2012.