Stacking defects in GaP nanowires: Electronic structure and optical properties

Formation of 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 homostructure band alignment. Twin boundaries and stacking faults (wider regions of the wurtzite phase) lead to the introduction of shallow trap states observed in photoluminescence studies. These defect states may cause undesired radiative or nonradiative recombination impacting on the performance of nanowire-based devices.