The Cu–Sn–S precursor was sulfurized in
sulfur containing atmosphere at 500 C to form CTS thin film
by Su et al., and its optical energy gap was determined to be
1.47 eV.11) The energy gap of orthorhombic (Pmn21) CTS
with petrukite structure thin film, deposited by dc magnetron
sputtering and followed by sulfurization in N2 + S2 vapor
atmosphere at 520 C, was determined to be 1.60 eV by
Fernandes et al.12) Thus CTS is a very important semiconductor
which attracts great attention of its promising optical,
thermal and mechanical properties.1)