Synthesis of Homogeneously Alloyed Cu2−x(SySe1−y) Nanowire Bundles with Tunable Compositions and Bandgaps

• Published in: Advanced functional materials 2010-12, Vol.20 (23), p.4190-4195
• Main Authors: Xu, Jun, Tang, Yong-Bing, Chen, Xue, Luan, Chun-Yan, Zhang, Wen-Feng, Zapien, Juan Antonio, Zhang, Wen-Jun, Kwong, Hoi-Lun, Meng, Xiang-Min, Lee, Shuit-Tong, Lee, Chun-Sing
• Format: Article
• Language: English
• Subjects: copper chalcogenides; nanowires; ternary alloy; tunable bandgap; Végard's Law
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201000771

Bundles of homogeneously alloyed Cu2−x(SySe1−y) nanowires with various compositions (0 ≤ y ≤ 1) are controllably prepared via a simple water‐evaporation method under mild conditions. It is found that the nanowire bundles have similar copper contents (0.37 ≤ x ≤ 0.44) and morphologies, and the same face centered cubic (fcc) crystal structure and growth orientation of [110] over the entire composition range of y. To the best of the authors' knowledge, this is the first report on cubic phased ternary Cu2−x(SySe1−y) compounds. It is found that lattice parameter of the Cu2−x(SySe1−y) compound changes linearly with the S content. It is also shown that the direct and the indirect bandgaps of the nanowires vary quadratically with the S content and have bowing parameters of 0.20 and 0.21 eV respectively. Energy‐gap‐tuning via compositional change is achieved for both the direct (1.48−1.87 eV) and the indirect (0.50−0.90 eV) bandgaps. The trends of lattice parameter and bandgap variations are consistent with those described by Végard's Law. Bundles of homogeneously alloyed Cu2−x(SySe1−y) nanowires with lengths of several hundreds of micrometers and diameters of 200−500 nm are controllably prepared over the entire composition range of y (0 ≤ y ≤ 1). The trends of lattice parameter and bandgap variations with composition are in consistent with those described by Végard's Law.