In this work, top-down fabrication methods for fabricating high optical quality gallium indium phosphide (GaInP) nanopillar/disk arrays are investigated for optoelectronic applications. Time-resolved photoluminescence (TRPL) measurements are used to characterize the fabricated nanostructures and the results are compared to the properties of a reference GaInP ‘slab’. Photoluminescence (PL) spectra and carrier lifetimes are characterized for the fabricated GaInP structures embedded in a highly transparent film. Additionally, using GaInP structures on a gallium arsenide (GaAs) substrate the effect of a sulphur-oleylamine based surface passivation procedure is investigated. This was done for the purpose of improving the PL intensities, increase carrier lifetimes and prevent photodegradation by passivating the surface states.