Abstract
The bronze-phase TiO2(B) has an open atomic framework that makes it a good candidate for applications in photochemical and electrochemical conversion of energy. However, the synthesis of bronze-phase TiO2(B) thin films on perovskite substrates, such as SrTiO3 (STO), which is one of the most conventional versatile substrates for oxide epitaxy, has been extremely challenging owing to the preferential formation of the anatase TiO2 over TiO2(B). The main reason is that the anatase TiO2 has not only a smaller lattice mismatch than TiO2(B), but also a better structural symmetry match when grown on STO. Here, we demonstrate a way to circumventing this problem by using a VO2(B) buffer layer, yielding the growth of a high-quality single crystalline TiO2(B) film on a (001)-oriented STO substrate. From the resulting TiO2(B) film, we found that this film has a large optical bandgap of ∼3.6 eV, which is close to the known theoretical value, the largest among TiO2 polymorphs, and useful for developing high-power energy devices.
Original language | English |
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Article number | 133903 |
Journal | Applied Physics Letters |
Volume | 117 |
Issue number | 13 |
DOIs | |
State | Published - Sep 28 2020 |
Funding
This work was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The STEM specimen preparation was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. The spectroscopic ellipsometry measurement was performed with the support from the Research Center Program of the Institute for Basic Science in Korea (Grant No. IBS-R009-D1).