Electronic structure of SrTi${}_{1-x}$V${}_x$O${}_3$ films studied by $insitu$ photoemission spectroscopy: Screening for a transparent electrode material

Abstract

This study investigated the electronic structure of SrTi${}_{1-x}$V${}_x$O${}_3$ (STVO) thin films, which are solid solutions of strongly correlated transparent conductive oxide (TCO) SrVO${}_3$ and oxide semiconductor SrTiO${}_3$, using $insitu$ photoemission spectroscopy. STVO is one of the most promising candidates for correlated-metal TCO because it has the capability of optimizing the performance of transparent electrodes by varying $x$. Systematic and significant spectral changes were found near the Fermi level ($E_{\mathrm{F}}$) as a function of $x$, while the overall electronic structure of STVO is in good agreement with the prediction of band structure calculations. As $x$ decreases from 1.0, spectral weight transfer occurs from the coherent band near $E_{\mathrm{F}}$ to the incoherent states (lower Hubbard band) around 1.0-1.5 eV. Simultaneously, a pseudogap is formed at $E_{\mathrm{F}}$, indicating a significant reduction in quasiparticle spectral weight within close vicinity of $E_{\mathrm{F}}$. This pseudogap seems to evolve into an energy gap at $x$ = 0.4, suggesting the occurrence of a composition-driven metal-insulator transition. From angle-resolved photoemission spectroscopic results, the carrier concentration $n$ changes proportionally as a function of $x$ in the metallic range of $x$ = 0.6-1.0. In contrast, the mass enhancement factor, which is proportional to the effective mass ($m^{\ast }$), does not change significantly with varying $x$. These results suggest that the key factor of $n/m^{\ast }$ in optimizing the performance of correlated-metal TCO is tuned by $x$, highlighting the potential of STVO to achieve the desired TCO performance in the metallic region.

32 pages, 5 main figures, and 7 supplementary figures

References in corpus (4)

• Momentum-resolved spectral functions of SrVO${}_3$ calculated by LDA+DMFT
• Hole-doping-induced changes in the electronic structure of La${}_{1-x}$Sr${}_x$FeO${}_3$ : soft x-ray photoemission and absorption study of epitaxial thin films
• Critical test for Altshuler-Aronov theory: Evolution of the density of states singularity in double perovskite Sr${}_2$FeMoO${}_6$ with controlled disorder
• Gradual Disappearance of the Fermi Surface near the Metal-Insulator Transition in La${}_{1-x}$Sr${}_x$MnO${}_3$