Abstract

Abstract
Precise control over the defect density, a high Ga content, and uniform stoichiometry are critical for controlling the physical and optical properties of Cu(In,Ga)Se2 (CIGS) nanowires (NWs). In this study, we investigated the synthesis of epitaxially grown, single-crystal CIGS NWs by a vapour-phase transport method using multiple sources of Ga2Se3, In2Se3, and Cu2Se as the precursors. No catalysts were employed, and r-cut Al2O3 substrates were used for the fabrication of the NWs. The synthesized CIGS NWs had a uniform composition along their length, and the NWs with the highest Ga/(In + Ga) content ratio (0.8) had a chalcopyrite structure. The bandgap energy of the CIGS NWs was higher than that of typical CIGS thin films grown by co-evaporation methods because of the high Ga content ratio. These single-crystal CIGS NWs offer an attractive platform for exploring various concepts related to hierarchical nanostructures and devices based on fully epitaxial semiconductor structures.