ABSTRACT
Nanowires (NWs) have come into the spotlight for future integrated optoelectronic devices. Generally, III–V NWs grown on silicon (Si) substrates without any special treatments have messy and randomly oriented morphology as shown by scanning electron microscopy images. In terms of the general planar growth of III–V semiconductor materials on Si, a high density of defects is the result due to their mismatch in lattice parameters and thermal expansion coefficients, and naturally, NWs are no exception. In terms of GaAs NWs on Si, for instance, silicon has a diamond crystal structure with homogeneous two-fcc sublattices. The GaAs layers and NWs were grown on Si substrates by horizontal-flow low-pressure metal–organic chemical vapor deposition. Photoluminescence (PL) is routinely used to characterize the optical properties of GaAs NWs. Bare GaAs NWs, however, emit only very weak PL, even at low temperatures, which is due to the high density of surface states that act as nonradiative recombination centers.
