Carrier dynamics and recombination mechanisms in InP twinning superlattice nanowires.

Abstract

Nominal dopant-free zinc blende twinning superlattice InP nanowires have been grown with high crystal-quality and taper-free morphology. Here, we demonstrate its superior optical performance and clarify the different carrier recombination mechanisms at different temperatures using a time resolved photoluminescence study. The existence of regular twin planes and lateral overgrowth do not significantly increase the defect density. At room temperature, the as-grown InP nanowires have a strong emission at 1.348 eV and long minority carrier lifetime (∼3 ns). The carrier recombination dynamics is mainly dominated by nonradiative recombination due to surface trapping states; a wet chemical etch to reduce the surface trapping density thus boosts the emission intensity and increases the carrier lifetime to 7.1 ns. This nonradiative recombination mechanism dominates for temperatures above 155 K, and the carrier lifetime decreases with increasing temperature. However, radiative recombination dominates the carrier dynamics at temperature below ∼75 K, and a strong donor-bound exciton emission with a narrow emission linewidth of 4.5 meV is observed. Consequently, carrier lifetime increases with temperature. By revealing carrier recombination mechanisms over the temperature range 10-300 K, we demonstrate the attraction of using InP nanostructure for photonics and optoelectronic applications.