Synthesis of low resistive p type Cu4O3 thin films by DC reactive magnetron sputtering and conversion of Cu4O3 into CuO by laser irradiation

Copper oxide thin films are a topic of intense investigation by several researchers. Copper reacting with oxygen, depending upon the available energy, forms CuO, Cu2O and Cu4O3 phases. Among these, Cu4O3 is a difficult phase to prepare. In the present communication, we report the preparation and properties of the stable phase of Cu4O3. These Cu4O3 thin films have been prepared at room temperature (300 K) on borosilicate glass by reactive DC magnetron sputtering. Cu4O3 thin films (of thickness 265 +/- 5 nm) are p-type semiconductors (hole density 2.4 x 10(18) cc(-1) and Hall mobility 0.04 cm(2) V-1 s(-1)) and show a low resistivity (55 Omega cm). They have a direct band gap of 2.34 eV and an indirect band gap of 1.50 eV. The surface work function of Cu4O3 (measured by Kelvin Probe technique) is 5.35 +/- 0.01 eV. Cu4O3 films are irradiated with laser radiation of 532 nm wavelength and 10 MW cm(-2) (120 s) power density. It shows a phase transformation to CuO which is confirmed by the Raman Spectroscopy measurements.