Hydrogen-mediated nanostructuring of dilute nitride semiconductors

The deposition of hydrogen-opaque metallic wires on GaAsN and subsequent hydrogen irradiation allows creating planar regions, where the properties of GaAsN are alternated with those of GaAs (i.e., hydrogenated GaAsN) in a fully controllable manner. We present here a breakthrough of this approach showing the possibility to fabricate a new class of semiconductor nanostructures. Firstly, we report on a detailed study of H kinetics in GaAsN. By combining secondary ions mass spectrometry (SIMS) measurements with a model developed for hydrogen diffusion in a crystal with high trap density (namely, N atoms), we demonstrate that a tight spatial control of H-N interaction in dilute nitrides is feasible. Then, we present the first nanostructures fabricated with the masked-hydrogenation procedure. Specifically, we study the properties of H-structured GaAsN/GaAs wires having different width. In the case of the narrowest metallic wires (w - 80 nm), photoluminescence (PL) shows a blueshift of the ground state energy and a 50-fold increase in the PL efficiency. Moreover, time-resolved micro-PL displays a marked slow-down of the carrier recombination dynamics in the single structure. This indicates the occurrence of carrier quantum confinement that leads to a reduced density of states of the system, which changes its dimensionality from 3D to 2D. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim