Electrical and optical properties of core-shell InAs-InAsyP1-y nanowires

Although III-V semiconductor nanowires are attractive building blocks for future nanoscale optoelectronic applications, their optical and electrical properties are unsatisfactory compared to those of the bulk materials. In particular, the large surface-to-volume ratio of a nanowire system leads to a high density of states along its surface, acting as an efficient non-radiative recombination center. Growing a higher bandgap material on the nanowire surface (i.e., core-shell structure) reduces the carrier recombination loss because the shell layer spatially separates charge carriers in the core region from the surface states. Nevertheless, a large difference in the crystal lattice parameters between the core and shell layer can generate misfit dislocations at the heterointerface, providing new carrier scattering centers. Here, InAs-InAs0.75P0.25 and InAs-InP core-shell structured nanowires were grown and their electrical and optical properties were compared with those of bare InAs nanowires. The electron mobility is highest for the InAs-InAs0.75P0.25 nanowires while the strongest photoluminescence intensity is achieved from InAs-InP nanowires. This suggests that the misfit dislocations along the heterointerface of the nanowire need to be considered for applications of electrical devices.