Pulsed laser deposited Be&ITx&ITZn1-&ITx&IT O1-&ITy&ITS&ITy&IT quaternary alloy films: structure, composition, and band gap bowing

摘要

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 O-2 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 O(2- )by bigger S2-. Besides, due to the introduction of Be0 with a wide band gap, BeZnOS quaternary films exhibited wider band gaps than the ternary ZnOS films with similar S contents. As the O-2 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. (C) 2017 Elsevier B.V. All rights reserved.