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arXiv · 2105.10706

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

Tatsuhiko Kanda·Daisuke Shiga·Ryu Yukawa·Naoto Hasegawa·Duy Khanh Nguyen·Xianglin Cheng·Ryosuke Tokunaga·Miho Kitamura·Koji Horiba·Kohei Yoshimatsu·Hiroshi Kumigashira
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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 ${in situ}$ 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 (${E_{\rm F}}$) 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 ${E_{\rm F}}$ to the incoherent states (lower Hubbard band) around 1.0-1.5 eV. Simultaneously, a pseudogap is formed at ${E_{\rm F}}$, indicating a significant reduction in quasiparticle spectral weight within close vicinity of ${E_{\rm F}}$. 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 (${m^*}$), does not change significantly with varying ${x}$. These results suggest that the key factor of ${n/m^*}$ 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.

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Tatsuhiko Kanda, Daisuke Shiga, Ryu Yukawa, Naoto Hasegawa, Duy Khanh Nguyen, Xianglin Cheng, Ryosuke Tokunaga, Miho Kitamura, Koji Horiba, Kohei Yoshimatsu, Hiroshi Kumigashira. 2021-05-22. Electronic structure of SrTi$_{1-x}$V$_x$O$_3$ films studied by ${\it in\ situ}$ photoemission spectroscopy: Screening for a transparent electrode material. https://doi.org/10.1103/physrevb.104.115121

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