Growth and optical properties of a- and c-axis oriented Zn-ZnO nanocables fabricated via a facile one-step process

Abstract This study reports the growth of Zn–ZnO nanocables grown along the [ 1 1 2 ¯ 0 ] (a-plane) and [0 0 0 1] (c-plane) directions. The a-plane-oriented nanocables were synthesized via one-step thermal evaporation and condensation, whereas the highly ordered c-plane-oriented nanocables were synthesized via a vapor–solid–solid growth method with Sn catalysts. Photoluminescence (PL) measurements show that the near-band-edge emissions of both types of Zn–ZnO nanocables are blue-shifted compared to those of ZnO nanotubes without Zn cores, which is caused by compressive stress. Temperature-dependent PL spectra reveal that there are two dominant emissions for each type of nanocables at low temperatures. The emission attributed to excitons bound to neutral donors is common to both types of nanocables and persistent at room temperature. The other emission involves different excitonic transitions, which are related to different surface planes.