Twin boundaries in GaP nanowires: Electronic structure and optical properties

Formation of multiple twin boundaries during the growth of semiconductor nanowires is very common. However, the effects of such planar defects on the electronic and optical properties of nanowires are not very well understood. Here, we use a combination of ab initio simulation and experimental techniques to study these effects. Twin boundaries in GaP are shown to act as an atomically-narrow plane of wurtzite phase with a type-I band alignment homostructure. Presence of twin boundaries leads to the introduction of shallow trap states observed in photoluminescence studies. These effects should have a profound impact on the efficiency of nanowire-based devices.