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Formation of High‐Pressure Phase of Titanium Dioxide (TiO 2 ‐II) Thin Films by Vapor‐Liquid‐Solid Growth Process on GaAs Substrate
Author(s) -
Das Anindita,
Nag Chowdhury Basudev,
Saha Rajib,
Sikdar Subhrajit,
Sultana Jenifar,
Kumar Dalapati Goutam,
Chattopadhyay Sanatan
Publication year - 2019
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201800640
Subject(s) - cathodoluminescence , x ray photoelectron spectroscopy , materials science , substrate (aquarium) , titanium dioxide , titanium , thermal expansion , phase (matter) , analytical chemistry (journal) , chemical engineering , composite material , metallurgy , optoelectronics , chemistry , oceanography , organic chemistry , chromatography , luminescence , engineering , geology
In this work, the high pressure phase of titanium dioxide (TiO 2 ‐II) film is grown with vapor‐liquid‐solid (VLS) method on <100>‐GaAs substrate by utilizing the natural process‐induced‐strain, originating from the thermo‐elastic mismatch between TiO 2 and GaAs in VLS process. The mismatches in thermal expansion coefficient and elastic constant of TiO 2 and GaAs are Δ α ≈ 55 % and Δ Y ≈ 170 % which incorporate a substantial amount of stress (≈GPa) during cooling from the growth temperature (500 °C). SEM imaging suggests the formation of a continuous film and cross‐sectional TEM image confirmed its high crystalline quality. XRD peaks at 2θ = 31.30 0 and 58.67 0 confirm the formation of [111] and [212]‐planes of TiO 2 ‐II phase and its chemical states are analyzed from X‐ray photoelectron spectroscopy (XPS) measurements. The bandgap of TiO 2 ‐II phase is estimated to be 2.88 eV from cathodoluminescence study for the first time which agrees satisfactorily with the theoretical predictions reported.