Phase Transformation and Superstructure Formation in (Ti0.5, Mg0.5)N Thin Films through High-Temperature Annealing

(Ti0.5, Mg0.5)N thin films were synthesized by reactive dc magnetron sputtering from elemental targets onto c-cut sapphire substrates. Characterization by θ–2θ X-ray diffraction and pole figure measurements shows a rock-salt cubic structure with (111)-oriented growth and a twin-domain structure. The...

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Bibliographic Details
Published in:Coatings (Basel) 2021-01, Vol.11 (1), p.89
Main Authors: Gharavi, Mohammad Amin, le Febvrier, Arnaud, Lu, Jun, Greczynski, Grzegorz, Alling, Björn, Armiento, Rickard, Eklund, Per
Format: Article
Language:English
Subjects:
Annealing
Approximation
Bands
Density functional theory
Energy
Gas flow
Gases
Heat conductivity
High temperature
Ion beams
magnesium nitride
Magnetron sputtering
Mathematical analysis
Nitrogen
Phase transitions
Sapphire
Scanning electron microscopy
Scanning transmission electron microscopy
Seebeck effect
Spectrum analysis
sputtering
Substrates
Superstructures
ternary nitride
thermoelectrics
Thin films
Titanium
titanium nitride
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Summary:(Ti0.5, Mg0.5)N thin films were synthesized by reactive dc magnetron sputtering from elemental targets onto c-cut sapphire substrates. Characterization by θ–2θ X-ray diffraction and pole figure measurements shows a rock-salt cubic structure with (111)-oriented growth and a twin-domain structure. The films exhibit an electrical resistivity of 150 mΩ·cm, as measured by four-point-probe, and a Seebeck coefficient of −25 µV/K. It is shown that high temperature (~800 °C) annealing in a nitrogen atmosphere leads to the formation of a cubic LiTiO2-type superstructure as seen by high-resolution scanning transmission electron microscopy. The corresponding phase formation is possibly influenced by oxygen contamination present in the as-deposited films resulting in a cubic superstructure. Density functional theory calculations utilizing the generalized gradient approximation (GGA) functionals show that the LiTiO2-type TiMgN2 structure has a 0.07 eV direct bandgap.
ISSN:2079-6412
2079-6412
DOI:10.3390/coatings11010089