Enhanced growth and properties of non-catalytic GaAs nanowires via Sb surfactant effects
Akhil Ajay, Hyowon W. Jeong, T. Schreitmüller, Markus Döblinger, Daniel Ruhstorfer, Nitin Mukhundhan, P. A. L. M. Koolen, Jonathan J. Finley, Gregor Koblmüller
Abstract
We report the effects of antimony (Sb) surfactant on the growth and correlated structural and optical properties of non-catalytic GaAs nanowires (NW) grown by selective area epitaxy on silicon. Strong enhancements in the axial growth with very high aspect ratio up to 50 are observed by the addition of small traces of Sb (1%–2%), contrasting the commonly reported growth limiting behavior of Sb in GaAs(Sb) NWs. The Sb surfactant effect modifies the growth facet structure from a pyramidal-shaped growth front terminated by {1–1–0} planes to a flat (111)B growth plane, that is even further improved by the presence of Si co-dopants. Additional benefits are seen by the substantial change in microstructure, from a heavily defected layer stacking in Sb-free GaAs NWs to a twinned phase-pure zinc blende structure in Sb-mediated GaAs(Sb) NWs. We directly confirm the impact of the altered microstructure on the optical emission and carrier recombination dynamics via observation of long, few-ns carrier lifetimes in the GaAs(Sb) NWs using steady-state and time-resolved photoluminescence spectroscopy.