Dense, Regular GaAs Nanowire Arrays by Catalyst-Free Vapor Phase Epitaxy for Light Harvesting

Abstract

Density dependent growth and optical properties of periodic arrays of GaAs nanowires (NWs) by fast selective area growth MOVPE are investigated. As the period of the arrays is decreased from 500 nm down to 100 nm, a volume growth enhancement by a factor of up to four compared with the growth of a planar layer is observed. This increase is explained as resulting from increased collection of precursors on the side walls of the nanowires due to the gas flow redistribution in the space between the NWs. Normal spectral reflectance of the arrays is strongly reduced compared with a flat substrate surface in all fabricated arrays. Electromagnetic modeling reveals that this reduction is caused by antireflective action of the nanowire arrays and nanowire-diameter dependent light absorption. Irrespective of the periodicity and diameter, Raman scattering and grazing angle X-ray diffraction show signal from zinc blende and wurtzite phases, the latter originating from stacking faults as observed by high resolution transmission electron microscopy. Raman spectra contain intense surface phonons peaks, whose intensity depends strongly on the nanowire diameters as a result of potential structural changes and as well as variations of optical field distribution in the nanowires.

Growth kinetics and morphological analysis of homoepitaxial GaAs fins by theory and experiment

“…where the incorporation dynamics is faster, so that material eventually diffuses away from the {110} facets toward the top, as indicated by the arrows. A similar behavior was already reported for NW growth in SAE by MOCVD 30,31 . The difference in growth rate for the two facets inherently depends on the material transfer from one facet to the other and is mediated by the surface diffusion.…”

Selective area epitaxy of III–V nanostructure arrays and networks: Growth, applications, and future directions

“…SAE of III-As nanowire arrays are well developed by different research groups, achieving highly ordered nanowire arrays, surface passivation, and doping 3,[73][74][75][76] [see Fig. 2(e)].…”