  LaVO$_3$ (LVO) has been proposed as a promising material for photovoltaics
because its strongly correlated \textit{d} electrons can facilitate the
creation of multiple electron-hole pairs per incoming photon, which would lead
to increased device efficiency. In this study, we intentionally grow
off-stoichiometric LVO films by changing the growth conditions such as laser
fluence. Our aim is to study how deviating La:V stoichiometries affect the
electronic properties of LVO thin films. We find that the off-stoichiometry
clearly alters the physical properties of the films. Structural
characterization shows that both La-rich and V-rich films have different levels
of structural distortion, with La-rich (V-rich) films showing a larger
(smaller) out-of-plane lattice parameter compared to what one would expect from
epitaxial strain effects alone. Both types of films show deviation from the
behavior of bulk LVO in optical measurement, i.e., they do not show signatures
of the expected long range orbital order, which can be a result of the
structural distortions or the presence of structural domains. In transport
measurements, La-rich films display clear signatures of electronic phase
separation accompanying a temperature induced metal-insulator transition, while
V-rich films behave as Mott insulators. The out-of-plane lattice parameter
plays a crucial role in determining the transport properties, as the crossover
from Mott-insulating to disorder-induced phase-separated behavior occurs around
a lattice parameter value of 3.96 $\overset{\circ}{\mathrm{A}}$, quite
different from what has been previously reported.

Strongly Correlated Electrons