Surface optical phonon propagation in defect modulated nanowires

摘要

Planar defects, such as stacking faults and twins, are the most common defects in ni-V semiconductor nanowires. Here we report on the effect of surface perturbation caused by twin planes on surface optical (SO) phonon modes. Self-catalyzed GaAs nanowires with varying planar defect density were grown by molecular beam epitaxy and investigated by Raman spectroscopy and transmission electron microscopy (TEM). SO phonon peaks have been detected, and the corresponding spatial period along the nanowire axis were measured to be 1.47 μm (±0.47/μm) and 446nm (±35nm) for wires with twin densities of about 0.6 (±0.2) and 2.2 (±0.18) per micron. For the wires with extremely high density of twins, no SO phonon peaks were detected. TEM analysis of the wires reveal that the average distance between the defects are in good agreement with the SO phonon spatial period determined by Raman spectroscopy,