Photoluminescence and Raman scattering in axial Si/Ge nanowire heterojunctions

Abstract

In crystalline, dislocation-free, Si/Ge nanowire axial heterojunctions grown using the vapor-liquid-solid technique, photoluminescence and Raman spectroscopy reveal a SiGe alloy transition layer with preferential chemical composition and strain. In addition to the lattice mismatch, strain in Si/Ge nanowires is observed from a temperature dependent study to be affected by the difference in Si and Ge thermal expansion. The conclusions are supported by analytical transmission electron microscopy measurements.