University of Oulu

Nepomniashchaia, N., Vetokhina, V., Chvostova, D., Bryknar, Z., Dejneka, A., & Tyunina, M. (2022). Low-temperature NIR-VUV optical constants of (001) LaAlO 3 crystal. Optical Materials Express, 12(8), 3081.

Low-temperature NIR-VUV optical constants of (001) LaAlO3 crystal

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Author: Nepomniashchaia, Natalia1,2; Vetokhina, Volha1; Chvostova, Dagmar1;
Organizations: 1Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Prague, Czech Republic
2Czech Technical University in Prague, Faculty of Nuclear Sciences and Physical Engineering, Trojanova 13, 120 00 Prague 2, Czech Republic
3Microelectronics Research Unit, Faculty of Information Technology and Electrical Engineering, University of Oulu, P. O. Box 4500, Finland
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Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.2 MB)
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Language: English
Published: Optical Society of America, 2022
Publish Date: 2023-02-08


The optical constants and dielectric function of (001) LaAlO3 crystal were investigated at low temperatures down to 10 K in the NIR-VUV spectral range (photon energies 0.8–8.8 eV). Reflection variable angle spectroscopic ellipsometry and transmission spectroscopy were applied. Interband transitions were examined using the Tauc plots and the critical-point analysis. At room temperature, the indirect bandgap of 5.6 ± 0.01 eV and the lowest-energy direct transition at 7.2 ± 0.03 eV were detected. On cooling to 10 K, a blueshift of ∼0.2 eV and ∼0.1 eV was observed for the indirect and direct transitions, respectively. In the transparency spectral range, the index of refraction was found to be nearly temperature-independent and vary with photon energy from 2.0 (1 eV) to 2.5 (5.5 eV). It was suggested that the excellent thermal stability of the index of refraction may be related to the revealed thermally stable interband transitions. The results are of importance for modeling and design of modern optical devices.

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Series: Optical materials express
ISSN: 2159-3930
ISSN-E: 2159-3930
ISSN-L: 2159-3930
Volume: 12
Issue: 8
Article number: 3081
DOI: 10.1364/ome.461098
Type of Publication: A1 Journal article – refereed
Field of Science: 213 Electronic, automation and communications engineering, electronics
216 Materials engineering
114 Physical sciences
Funding: European Structural and Investment Funds and the Ministry of Education, Youth and Sports of the Czech Republic through Programme "Research, Development and Education" (SOLID21 - CZ.02.1.01/0.0/0.0/16_019/0000760); The Grant Agency of the Czech Technical University in Prague (SGS22/182/OHK4/3T/14).
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