Laser chemical etching of Cu2O

Thin films of highly oriented Cu2O on single crystalline MgO (100) substrates were etched by a focused Ar+ laser operated at 458 nm. Two different etch gases, Cl2 and SOCl2, were used. The etch rate was examined as a function of temperature and total pressure. Scanning force microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy were used to examine the solid reaction products and the morphology. The experimental results were compared with thermodynamic calculations. SOCl2 etched Cu2O more effectively than Cl2. With SOCl2 the etching started at 480 K while etching was initiated at temperatures above 800 K for Cl2. The apparent activation energies in the temperature range 900–1300 K (surface reaction control) were determined to 130 and 180 kJ/mol for Cl2 and SOCl2, respectively. The etch rate at 1100 K was independent of the partial pressure of SOCl2 in the pressure region 0.1–50 mbar, while for Cl2 an experimental reaction order of 0.3 was obtained in the same pressure region. The results of the thermodynamic calculations were in good agreement with experimental results.