  SrVO3 thin films with a high figure of merit for applications as transparent
conductors were crystallized from amorphous layers using solid phase epitaxy
(SPE). Epitaxial SrVO3 films crystallized on SrTiO3 using SPE exhibit a room
temperature resistivity of 2.5 x 10-5 Ohms cm, a residual resistivity ratio of
3.8, and visible light transmission above 0.5 for a 60 nm-thick film. SrVO3
layers were deposited at room temperature using radio-frequency sputtering in
an amorphous form and subsequently crystallized by heating in controlled gas
environment. The lattice parameters and mosaic angular width of x-ray
reflections from the crystallized films are consistent with partial relaxation
of the strain resulting from the epitaxial mismatch between SrVO3 and SrTiO3. A
reflection high-energy electron diffraction study of the kinetics of SPE
indicates that crystallization occurs via the thermally activated propagation
of the crystalline/amorphous interface, similar to SPE phenomena in other
perovskite oxides. Thermodynamic calculations based on density functional
theory predict the temperature and oxygen partial pressure conditions required
to produce the SrVO3 phase and are consistent with the experiments. The
separate control of deposition and crystallization conditions in SPE presents
new possibilities for the crystallization of transparent conductors in complex
geometries and over large areas.
