Deposition of epitaxial Cu₂O films on (100) MgO by laser ablation and their processing using ion beams

Abstract

Epitaxial thin films of Cu₂O have been deposited on (100) MgO substrates by pulsed excimer laser ablation technique. Chemical polishing of the substrates by etching them in hot phosphoric acid prior to film deposition is found to be a critical step in realizing epitaxy. A KrF excimer laser operating at 248 nm wavelengths was used for ablation. The depositions were carried out at the laser energy density of 2 J/cm₂ and the pulse repetition rate of 5 Hz. The substrate temperature was held at 700° C and the oxygen partial pressure during deposition and cooling was 10_-3 Torr. The epitaxial nature of the deposited films was established via X-ray diffraction (XRD) and Rutherford back-scattering (RBS) channelling measurements. The epitaxial films thus obtained were then subjected to ion bombardment for studies of damage formation. Implantations were carried out using 110 keV Ar⁺ ions over a dose range between 5×10¹⁴ and 1.5×10¹⁶ions/cmz. The as-grown and implanted samples were subjected to resistivity versus temperature measurements in view of the importance of the Cu-O system in the context of the phenomenon of high temperature superconductivity.