Formation of vanadium oxide films on Cu3Au(100)

The initial growth of VOx has been investigated by low energy ion backscatt ering (NICISS), scanning tunnelling microscopy (STM), low energy electron d iffraction (LEED) and Auger electron spectroscopy (AES). Direct evaporation of vanadium onto the CU3Au(100) substrate gives rise to massive surface al loying, consequent oxygen exposure leads to the formation of rough vanadium oxide films of poor quality. A better way has been developed by forming a thin oxygen layer at the clean Cu3Au substrate which acts positively in two ways: firstly, it prevents completely the alloy formation, secondly, a str ong surface wetting of the vanadium oxide occurs resulting in two-dimension al layer growth of good quality. Depending on the pre-oxygen content at Cu3 Au(100), the amount of V deposition and annealing temperature, different ep itaxial layers of vanadium oxides can be prepared. Namely, three VOx specie s occur separately: an oxide with low oxygen content showing a quadratic cr ystallographic lattice, probably VO(100), V2O3(0001) with a hexagonal super lattice and finally, domains with a rectangular unit cell and VO2 stoichiom etry. As a consequence, oxygen treated CU3Au(100) is ideally suited as a me tal substrate for growing homogeneous 2D epitaxial vanadium metal oxides.