Epitaxial growth of vanadium films evaporated on nacl substrates

The epitaxial growth of vanadium (V) films evaporated on an NaCl cleavage surface has been studied by electron microscopy. It has been found that body-centered tetragonal (bct) VH_x (x≲0.1; a=0.301 nm, c=0.312 nm) and NaCl- type VO_y (y≒1.0; a' =0.408 nm) are formed on the substrate held at 270°C in the early growth stage of the film. With increasing film thickness, body-centered cubic (bcc) V is formed. When the substrate temperature is raised up to 400°C, bcc V films (a=0.302 nm) grow from the early growth stage. On the other hand, bct VH_x (x≒0.5; a=0.297 nm， c=0.338 nm) grows mainly when the substrate temperature is lowered to -170°C. The existence of oxygen and hydrogen atoms in the film was confirmed by nuclear reaction analysis and elastic recoil detection analysis respectively. The present paper has verified also that hydrogen and oxygen atoms which dissolve in V films, escape from the NaCl substrate.