Growth, structural and vibrating properties of CdSe–Ge, CdSe–Ge–CdSe, CdSe–Ge/Ge, Ge–GeSe heterostructure nanowires and GeSe nanobelts

Abstract

CdSe–Ge, CdSe–Ge–CdSe heterostructure nanowires, CdSe–Ge biaxial nanowire core/polycrystalline Ge sheath heterostructures, Ge–GeSe biaxial nanowires and GeSe nanobelts were grown via a simple one-step thermal evaporation of different molar ratios of CdSe and Ge, respectively. The CdSe and Ge subnanowires in CdSe–Ge biaxial nanowires (or triaxial nanowires) and the Ge and GeSe subnanowires in Ge–GeSe biaxial nanowires are single crystalline. A good epitaxial relationship exists in the interface between CdSe and Ge in CdSe–Ge biaxial nanowires and in the interface between Ge and GeSe in Ge–GeSe biaxial nanowires. Two sides of CdSe subnanowires in the CdSe–Ge–CdSe triaxial nanowire have an obvious differential in microstructure is just induced by the view angle. A structural model for the crystallographic relationship between CdSe and Ge in CdSe–Ge biaxial nanowires is given. The possible growth mechanism of CdSe–Ge based heterostructure nanowires is proposed as the co-growth mechanism. The vibrating properties of CdSe–Ge based heterostructure nanowires were investigated by micro-Raman spectroscopy. We observe a LO mode of CdSe, a LO (TO) mode of Ge and a LO and TO mode of GeSe in the five different nanostructures have the different wave-number shift in comparison with that of the responding bulk counterpart, respectively.