Infrared Optical Absorption in Low-spin Fe${}^{2+}$-doped SrTiO${}_3$

Abstract

Band gap engineering in SrTiO${}_3$ and related titanate perovskites has long been explored due to the intriguing properties of the materials for photocatalysis and photovoltaic applications. A popular approach in the materials chemistry community is to substitutionally dope aliovalent transition metal ions onto the B site in the lattice to alter the valence band. However, in such a scheme there is limited control over the dopant valence, and compensating defects often form. Here we demonstrate a novel technique to controllably synthesize Fe${}^{2+}$- and Fe${}^{3+}$-doped SrTiO${}_3$ thin films without formation of compensating defects by co-doping with La${}^{3+}$ ions on the A site. We stabilize Fe${}^{2+}$-doped films by doping with two La ions for every Fe dopant, and find that the Fe ions exhibit a low-spin electronic configuration, producing optical transitions in the near infrared regime and degenerate doping. The novel electronic states observed here offer a new avenue for band gap engineering in perovskites for photocatalytic and photovoltaic applications.

19 pages, 6 figures; supplemental information: 7 pages, 6 figures

References in corpus (4)

• Post density functional theoretical studies of highly polar semiconductive Pb(Ti${}_{1-x}$Ni${}_x$)O${}_{3-x}$ solid solutions: The effects of cation arrangement on band gap
• Electronic reconstruction at the isopolar LaTiO3/LaFeO3 interface: An x-ray photoemission and density functional theory study
• Charge transfer and hybrid ferroelectricity in (YFeO${}_3$)${}_n$/(YTiO${}_3$)${}_n$ magnetic superlattices
• Visible light carrier generation in co-doped epitaxial titanate films

Cited by in corpus (2)

• Interface structure, band alignment and built-in potentials at LaFeO${}_3$/$\text{n}$-SrTiO${}_3$ heterojunctions
• Dynamic Interface Rearrangement in LaFeO${}_3$ / $n$-SrTiO${}_3$ Heterojunctions