  We have investigated the evolution of the electronic properties of
La1-xSrxCrO3 (for the full range of x) epitaxial films deposited by molecular
beam epitaxy (MBE) using x-ray diffraction, x-ray photoemission spectroscopy,
Rutherford backscattering spectrometry, x-ray absorption spectroscopy,
electrical transport, and ab initio modeling. LaCrO3 is an antiferromagnetic
insulator whereas SrCrO3 is a metal. Substituting Sr2+ for La3+ in LaCrO3
effectively dopes holes into the top of valence band, leading to Cr4+ (3d2)
local electron configurations. Core-level and valence-band features
monotonically shift to lower binding energy with increasing x, indicating
downward movement of the Fermi level toward the valence band maximum. The
material becomes a p-type semiconductor at lower doping levels and an
insulator-to-metal transition is observed at x greater than or equal to 0.65,
but only when the films are deposited with in-plane compression via
lattice-mismatched heteroepitaxy. Valence band x-ray photoemission spectroscopy
reveals diminution of electronic state density at the Cr 3d t2g-derived top of
the valence band while O K-edge x-ray absorption spectroscopy shows the
development of a new unoccupied state above the Fermi level as holes are doped
into LaCrO3. The evolution of these bands with Sr concentration is accurately
captured using density functional theory with a Hubbard U correction of 3.0 eV
(DFT + U). Resistivity data in the semiconducting regime (x less than or equal
to 0.50) do not fit perfectly well to either a polaron hopping or band
conduction model, but are best interpreted in terms of a hybrid model. The
activation energies extracted from these fits are well reproduced by DFT + U.
