Pulsed laser deposited BexZn1-xO1-ySy quaternary alloy films: structure, composition, and band gap bowing
Abstract
In this work, c-axis preferentially oriented BexZn1-xO1-ySy (BeZnOS) quaternary alloy films were prepared successfully on c-plane sapphire by pulsed laser deposition for the first time. By appropriate adjustment of O2 pressure during the deposition, the grown films exhibited a single-phase hexagonal structure and good crystalline quality. The solid solubility of S in BexZn1-xO1-ySy quaternary alloy was significantly expanded (y ≤ 0.17 or y ≥ 0.35) as a result of simultaneous substitution of cation Zn2+ by smaller Be2+ and anion O2- by bigger S2-. Besides, due to the introduction of BeO with a wide band gap, BeZnOS quaternary films exhibited wider band gaps than the ternary ZnOS films with similar S contents. As the O2 pressure increased from 0.05 Pa to 6 Pa, the band gap of BeZnOS displayed an interesting bowing behavior. The variation range of the band gap was between 3.55 eV and 3.10 eV. The BeZnOS films with a wide band gap show potential applications in fabricating optoelectronic devices such as UV-detectors.
- Publication:
-
Applied Surface Science
- Pub Date:
- March 2018
- DOI:
- 10.1016/j.apsusc.2017.10.068
- Bibcode:
- 2018ApSS..433..674Z
- Keywords:
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- Quaternary BeZnOS alloy films;
- Pulsed laser deposition;
- Solubility limits;
- Band gap engineering