Temperature-dependent indirect gaps for two-dimensional bismuth oxychalcogenides probed by spectroscopic ellipsometry

Hsiang Lin Liu*, Hsiao Wen Chen, Nguyen Tuan Hung, Yi Cheng Chen, Heng Jui Liu, Chieh Ting Chen, Yu Lun Chueh, Ying Hao Chu, Riichiro Saito

*此作品的通信作者

研究成果: 雜誌貢獻期刊論文同行評審

摘要

In-plane optical properties of two-dimensional bismuth oxychalcogenides Bi2O2X (X = S, Se, and Te) are reported for a wide spectral range of 0.73-6.42 eV and at temperatures of 4.5-500 K by spectroscopic ellipsometry. At room temperature, Bi2O2S, Bi2O2Se, and Bi2O2Te exhibit an indirect band gap of 1.18 ± 0.02, 0.95 ± 0.01, and 0.60 ± 0.01 eV, respectively. As the temperature decreases, the indirect absorption edge of Bi2O2S undergoes a blueshift, while the indirect band gap of Bi2O2Se shows a redshift, and Bi2O2Te remains independent of temperature. The chalcogenide-dependent behavior as a function of temperature may be relevant to electron-phonon interactions in Bi2O2X materials. The observed pseudo-isotropic complex dielectric function and optical absorption coefficient by spectroscopic ellipsometry are directly compared with the first-principles calculations with a hybrid functional approach.

原文英語
文章編號035029
期刊2D Materials
11
發行號3
DOIs
出版狀態已發佈 - 2024 7月

ASJC Scopus subject areas

  • 一般化學
  • 一般材料科學
  • 凝聚態物理學
  • 材料力學
  • 機械工業

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