Self-standing III–V nanowires (NWs) are promising building blocks for future optoelectronic devices, in particular,
LEDs, lasers, photodetectors and solar cells. In this work we present the results of low temperature photoluminescence (PL)
characterization of GaAs NWs grown by Au-assisted molecular beam epitaxy (MBE) on the GaAs(111)B and Si(111)
substrates. PL spectra contain exciton peaks from zinc blende (ZB) and wurtzite (WZ) crystal structures of GaAs, influenced
by the quantum confinement effects. Theoretical estimates for the exciton radiation peaks depending on the crystal structure
and the NW radius are presented and compared to the experimental data.