Bandgap in Al1− x Sc x N

Aluminum scandium nitride (Al1−xScxN) layers deposited by reactive magnetron co-sputtering on sapphire 0001 substrates at 850 °C are epitaxial single-crystals for x ≤ 0.20. Their in-plane lattice constant increases linearly (3.111 + 0.744x Å) while the out-of-plane constant remains at 4.989 ± 0.005 ...

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Bibliographic Details
Published in:Applied physics letters 2013-03, Vol.102 (11)
Main Authors: Deng, Ruopeng, Evans, Sarah R., Gall, Daniel
Format: Article
Language:English
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Summary:Aluminum scandium nitride (Al1−xScxN) layers deposited by reactive magnetron co-sputtering on sapphire 0001 substrates at 850 °C are epitaxial single-crystals for x ≤ 0.20. Their in-plane lattice constant increases linearly (3.111 + 0.744x Å) while the out-of-plane constant remains at 4.989 ± 0.005 Å. Optical absorption indicates a band gap of 6.15–9.32x eV and a linearly increasing density of defect states within the gap. The average bond angle decreases linearly with x, suggesting a trend towards the metastable hexagonal-ScN structure. However, an anomalous decrease at x = 0.20 indicates a structural instability which ultimately leads to phase separated rock-salt ScN grains for x > 0.4.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4795784