Influence of surface passivation on the electrical properties of p-i-n GaAsP nanowires

The electrical properties of passivated and non-passivated axial pin junctions in GaAsP nanowires are investigated using electron-beam induced current microscopy. Organized self-catalyzed p i n nanowires having different segment lengths are grown by molecular-beam epitaxy on nanopatterned Si substrates. The nanowires are in situ passivated with a GaP shell. The position of the junction is found to be dependent on the length of the upper Be-doped segment evidencing the diffusion of Be atoms from the upper segment to the bottom part of the nanowire. Comparison between non-passivated and passivated nanowires shows a strong enhancement of the collection region after passivation. The results also prove the existence of a p-doped shell around the nanowires formed due to a parasitic radial growth. This shell is depleted in non-passivated nanowires; however, it becomes electrically active after surface passivation modifying the carrier collection pattern. Published under license by AIP Publishing.