(575b) Properties of InP/InAs/InP Core-Shell Nanopillars Grown by Metalorganic Vapor-Phase Epitaxy

Compound semiconductor nanowire devices are of great interest due to their size-dependent electrical and optical properties and their potential applications in nano-electronics. In this study, we demonstrate the growth of InP/InAs/InP core-shell nanopillars by metalorganic vapor-phase epitaxy (MOVPE). Indium droplets were used to catalyze crystal nucleation at low temperature. At 400°C and a V/III ratio of 86, hexagonal pillars were grown with smooth side walls and average widths and heights of 45 and 70 nm, respectively. Scanning and transmission electron microscopy, electron backscattered diffraction, and selected area electron diffraction revealed that the pillars were single crystal wurtzite and were bounded by {1,-1,0,0} sidewalls. Indium arsenide quantum wells were deposited on the nanopillars at 395°C and a V/III ratio of 120, and then capped with a thin layer of InP. The thickness of the quantum well was ~5 nm. Photoluminescence spectra at 77 K yielded a single intense band at 1750 nm (0.7 eV) with a full width at half maximum of 350 nm. These results indicated that there was phosphorus and arsenic intermixing with formation of an InAs_xP_1-x alloy. Further growth experiments varying temperature, V/III ratio, and hydrogen interrupt time succeeded in shifting the photoluminescence peak closer to the band gap for InAs. Detailed measurements of the optical and electrical properties of the core-shell nanopillars will be presented at the conference.