We used spatially resolved photoluminescence (PL) and resonant Raman
spectroscopy to study the electronic structure of single GaAs nanowires (NWs)
consisting of zinc-blende (ZB) and wurtzite (WZ) segments. For narrow ZB
segments and stacking faults the energy range of the observed PL peak
positions is found to deviate from that of the maxima in resonance Raman
profiles. These different energy ranges reflect the fact that the PL
recombination is dominated by spatially indirect transitions whereas the
resonance enhancement of Raman scattering is caused by direct transitions. Our
results provide evidence for the type II band alignment between ZB and WZ GaAs
and a coherent picture of all near-band-gap transition energies in GaAs NWs