Solid-phase epitaxial growth of the correlated-electron transparent conducting oxide SrVO3

Abstract

$\mathrm{SrV}{\mathrm{O}}_{3}$ thin films with a high figure of merit for applications as transparent conductors were crystallized from amorphous layers using solid phase epitaxy (SPE). Epitaxial $\mathrm{SrV}{\mathrm{O}}_{3}$ films crystallized on $\mathrm{SrTi}{\mathrm{O}}_{3}$ using SPE exhibit room-temperature resistivities as low as $5.2\ifmmode\times\else\texttimes\fi{}{10}^{--5}$ and $2.5\ifmmode\times\else\texttimes\fi{}{10}^{--5}\phantom{\rule{0.16em}{0ex}}\mathrm{\ensuremath{\Omega}}\phantom{\rule{0.16em}{0ex}}\mathrm{cm}$, residual resistivity ratios of 2.0 and 3.8, and visible light transmission maxima of 0.89 and 0.52 for film thicknesses of 16 and 60 nm, respectively. $\mathrm{SrV}{\mathrm{O}}_{3}$ layers were deposited at room temperature using radiofrequency sputtering in an amorphous form and subsequently crystallized by heating in a 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 $\mathrm{SrV}{\mathrm{O}}_{3}$ and $\mathrm{SrTi}{\mathrm{O}}_{3}$. 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, like 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 $\mathrm{SrV}{\mathrm{O}}_{3}$ phase and are consistent with the experiments. The separate control of deposition and crystallization conditions in SPE presents possibilities for the crystallization of transparent conductors in complex geometries and over large areas.