Band-Gap Reduction and Dopant Interaction in Epitaxial La,Cr Co-doped SrTiO3 Thin Films

RB Comes, PV Sushko, SM Heald, RJ Colby… - Chemistry of …, 2014 - ACS Publications
Chemistry of Materials, 2014ACS Publications
We show that by co-doping SrTiO3 (STO) epitaxial thin films with equal amounts of La and
Cr, it is possible to produce films with an optical band gap∼ 0.9 eV lower than that of
undoped STO. Sr1–x La x Ti1–x Cr x O3 thin films were deposited by molecular beam
epitaxy and characterized using X-ray photoelectron spectroscopy and X-ray absorption
near-edge spectroscopy to show that the Cr dopants are almost exclusively in the Cr3+
oxidation state. Extended X-ray absorption fine structure measurements and theoretical …
We show that by co-doping SrTiO3 (STO) epitaxial thin films with equal amounts of La and Cr, it is possible to produce films with an optical band gap ∼0.9 eV lower than that of undoped STO. Sr1–xLaxTi1–xCrxO3 thin films were deposited by molecular beam epitaxy and characterized using X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy to show that the Cr dopants are almost exclusively in the Cr3+ oxidation state. Extended X-ray absorption fine structure measurements and theoretical modeling suggest that it is thermodynamically preferred for La and Cr dopants to occupy nearest-neighbor A- and B-sites in the lattice. Transport measurements show that the material exhibits variable-range hopping conductivity with high resistivity. These results create new opportunities for the use of doped STO films in photovoltaic and photocatalytic applications.
ACS Publications
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