Low-temperature cathodoluminescence studies of GaAs nanowires in the SEM

We present data from cathodoluminescence (CL) studies of nanowires (NWs) grown from size-selected gold particles using metal-organic chemical vapour deposition. The NWs in this study all have a GaAs core and are surrounded by a shell of either AlGaAs or GaInP. The spatially and spectrally resolved CL studies were performed in a scanning electron microscope, in a temperature range of 4–300 K. The NWs were studied as-grown on their substrates in side view or transferred to Si substrates. We present data from single NWs, showing that the homogeneity of the emission is influenced by the growth conditions. A general observation is that the emission is much stronger, and more well-defined from the upper part of the NW. The shell emission varies in emission energy and spatial origin in an irregular fashion, probably linked to compositional variations in the shell.