  Copper sulfide (CuS) has garnered significant attention in various fields of
application due to its unique electronic, optical, and catalytic features. In
this study, we present the chemical vapor deposition (CVD)-based synthesis of
ultrathin CuS crystals as thin as 14 nm with lateral sizes up to 60 um. The
structure, morphology, and composition of the as-synthesized CuS crystals were
thoroughly characterized. Among our results, we measured the first-order
temperature coefficients of Raman shifts of CuS. Moreover, we showed that CuS
crystals exhibited an unexpected second harmonic generation (SHG), which is
attributed to the presence of defects in the CuS lattice. Our results suggest
that single crystalline CuS possesses a considerable potential for nonlinear
optical applications in conjunction with its current applications in
electronics and catalysis.
