Oxidation of the CoGa(100) surface at temperatures between 600 and 900 K

The oxidation of the CoGa(100) surface at temperatures above 600 K has been studied by means of thermal energy helium atom scattering and Auger electron spectroscopy. The oxide grows in large domains with an estimated mean size of 40 nm or larger, and with a constant thickness. The order of the oxide film can be improved by increasing the oxidation temperature. Although the oxide is found to be unstable at temperatures above 850 K, we are able to prepare an oxide film at 900 K by oxidizing the CoGa(100) surface and cooling the surface down in an oxygen atmosphere with a pressure larger than 2×10−7 mbar. The oxide film prepared at 900 K showed the highest reflectivity for He atoms, suggesting that the qualitatively best films are obtained at this high oxidation temperature.