A methodology for the preparation of nanoporous polyimide films with low dielectric constants

Cuprous oxide and copper thin films were potentiostatically electrodeposited in an acetate bath. Voltammetric curves were used to investigate the growth parameters; deposition potential, pH and temperature of the bath. Deposition potential dependency on the structural, morphological, optical and electronic properties of the films were investigated by the X-ray diffraction measurements, scanning electron micrographs, absorption measurements and dark and light current–voltage characterisations. It was observed that single phase polycrystalline Cu₂O can be deposited from 0 to ? 300 mV Vs saturated calomel electrode (SCE) and co-deposition of Cu and Cu₂O starts at ? 400 mV Vs SCE. Further increase in deposition potential from ? 700 mV Vs SCE produces single phase Cu thin films. Single phase polycrystalline Cu₂O thin films with cubic grains of 1–2 μm can be possible within the very narrow potential domain around ? 200 mV Vs SCE. Enhanced photoresponse in a photoelectrochemical cell is produced by the Cu₂O thin film prepared at ? 400 mV Vs SCE, where Cu is co-deposited with Cu₂O with random distribution of Cu spheres on the Cu₂O surface. This study reveals that a single deposition bath can be used to deposit both Cu and Cu₂O separately and an admixture of Cu–Cu₂O by controlling the deposition parameters.