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@article{1405512,
author = {Ondračka, Pavel and Holec, David and Nečas, David and Dvořáková, Eva and Elisabeth, Stéphane and Goullet, Antoinne and Zajíčková, Lenka},
article_location = {College PK},
article_number = {19},
doi = {http://dx.doi.org/10.1103/PhysRevB.95.195163},
keywords = {TixSi1-xO2; optical properties; DFT; band gap},
language = {eng},
issn = {2469-9950},
journal = {Physical Review B},
title = {Optical properties of TixSi1-xO2 solid solutions},
url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.95.195163},
volume = {95},
year = {2017}
}
TY - JOUR
ID - 1405512
AU - Ondračka, Pavel - Holec, David - Nečas, David - Dvořáková, Eva - Elisabeth, Stéphane - Goullet, Antoinne - Zajíčková, Lenka
PY - 2017
TI - Optical properties of TixSi1-xO2 solid solutions
JF - Physical Review B
VL - 95
IS - 19
SP - nestránkováno
EP - nestránkováno
PB - American Physical Society
SN - 24699950
KW - TixSi1-xO2
KW - optical properties
KW - DFT
KW - band gap
UR - https://journals.aps.org/prb/abstract/10.1103/PhysRevB.95.195163
N2 - In this work, we use density functional theory to predict the optical properties of TixSi1-xO2 solid solutions. The special quasirandom structure method and the simulated annealing procedure were applied to produce models of crystalline and amorphous TixSi1-xO2. These were fully structurally optimized by using the VASP package, while their electronic structure and optical properties were subsequently calculated by using the WIEN2k package employing the TB-mBJ potential. The calculated band gaps for a-TixSi1-xO2 evaluated by using the Tauc-like fitting approach are 8.53 eV for SiO2, quickly decreasing to 4.0 eV at x = 0.19, 3.52 eV at x = 0.34, and 3.24 eV for TiO2. Experimental samples were prepared by means of plasma-enhanced chemical vapor deposition to support the calculations. Ellipsometry and spectrophotometry yield a compositional trend for the experimental optical band gap comparable with our predictions: a quick decrease from 7.94 eV for pure SiO2 to 3.91 eV at x = 0.15, followed by a much slower decrease over the rest of the composition range ending at 3.26 eV for pure TiO2. A detailed analysis of anatase and rutile-based solid solutions reveals the introduction of silicon-induced oxygen states into the band gap in the TiO2-rich composition region, which results in the predicted reduction of the band gap. However, we show that the optical absorption of those states is negligible. We have obtained good agreement between the calculated and measured imaginary part of the dielectric function epsilon(i), especially for the TiO2-rich compositions. Finally, we predict an almost-linear refractive index change at 632.8 nm between a-SiO2 (1.36) and a-TiO2 (2.34), which was experimentally confirmed.
ER -
ONDRAČKA, Pavel, David HOLEC, David NEČAS, Eva DVOŘÁKOVÁ, Stéphane ELISABETH, Antoinne GOULLET a Lenka ZAJÍČKOVÁ. Optical properties of TixSi1-xO2 solid solutions. \textit{Physical Review B}. College PK: American Physical Society, 2017, roč.~95, č.~19, s.~nestránkováno, 10 s. ISSN~2469-9950. Dostupné z: https://dx.doi.org/10.1103/PhysRevB.95.195163.
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