Formation and Photoelectric Properties of Periodically Twinned ZnSe/SiO2 Nanocables

Nanoscaled coaxial materials with a periodically twinned ZnSe single crystal core and an amorphous silicon dioxide shell were synthesized by a simple thermal evaporation process. As-fabricated ZnSe/SiO2 core/shell nanowires and nanoribbons were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and a selected area electron diffraction (SAED) pattern. The periodically twinned ZnSe core with a twinning period of about 10-30 nm has a sphalerite crystal structure and a common growth direction of [11-1]. The amorphous SiO2 shell has a thickness of about 5 nm. The formation mechanism can be explained by the surface pressure stress from SiO2 shell to ZnSe core at the solid/liquid interface. The materials show strong cathodoluminescence (CL) related to the mixed light emission composed of band gap emission and defect emission. The single periodically twinned ZnSe/SiO2 nanowire has pronounced a photoconduction effect with a fast response time. The results suggest that the periodically twinned ZnSe nanocables have potential application in nanoscaled photodetectors and optical switches.