Fabrication of cuprous chloride films on copper substrate by chemical bath deposition

•Cuprous chloride (CuCl) was prepared on Cu substrate by chemical bath deposition.•HCl dip treatments facilitated the deposition of a full-coverage CuCl film.•A homogeneous elemental distribution was recognized for the deposited CuCl layer.•Excitonic and biexcitonic photoluminescence lines of CuCl films were well-resolved.•The free exciton emission line of CuCl films was observable at room temperature.

Polycrystalline CuCl films were fabricated by chemical bath deposition (CBD) on a Cu substrate at a low solution temperature of 90 °C.Continuous CuCl films were prepared using the copper (II) chloride (CuCl2) compound as the precursor for both the Cu2 + and Cl− sources, together with repeated HCl dip treatments. An HCl dip pretreatment of the substrate favored the nucleation of CuCl crystallites. Further, interrupting the film deposition and including an HCl dip treatment of the film growth surface facilitated the deposition of a full-coverage CuCl film.A dual beam (FIB/SEM) system with energy dispersive spectrometry facilities attached revealed a homogeneous CuCl layer with a flat-top surface and an average thickness of about 1 μm. Both the excitonic and biexcitonic emission lines were well-resolved in the 6.4 K photoluminescence spectra. In particular, the free exciton emission line was observable at room temperature, indicating the good quality of the CuCl films prepared by CBD.