%0 Journal Article
%T Fabrication of Axial and Radial Heterostructures for Semiconductor Nanowires by Using Selective-Area Metal-Organic Vapor-Phase Epitaxy
%A K. Hiruma
%A K. Tomioka
%A P. Mohan
%A L. Yang
%A J. Noborisaka
%A B. Hua
%A A. Hayashida
%A S. Fujisawa
%A S. Hara
%A J. Motohisa
%A T. Fukui
%J Journal of Nanotechnology
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/169284
%X The fabrication of GaAs- and InP-based III-V semiconductor nanowires with axial/radial heterostructures by using selective-area metal-organic vapor-phase epitaxy is reviewed. Nanowires, with a diameter of 50¨C300£¿nm and with a length of up to 10£¿¦Ìm, have been grown along the £¿ 1 1 1 £¿ B or £¿ 1 1 1 £¿ A crystallographic orientation from lithography-defined SiO2 mask openings on a group III-V semiconductor substrate surface. An InGaAs quantum well (QW) in GaAs/InGaAs nanowires and a GaAs QW in GaAs/AlGaAs or GaAs/GaAsP nanowires have been fabricated for the axial heterostructures to investigate photoluminescence spectra from QWs with various thicknesses. Transmission electron microscopy combined with energy dispersive X-ray spectroscopy measurements have been used to analyze the crystal structure and the atomic composition profile for the nanowires. GaAs/AlGaAs, InP/InAs/InP, and GaAs/GaAsP core-shell structures have been found to be effective for the radial heterostructures to increase photoluminescence intensity and have enabled laser emissions from a single GaAs/GaAsP nanowire waveguide. The results have indicated that the core-shell structure is indispensable for surface passivation and practical use of nanowire optoelectronics devices. 1. Introduction Interest in semiconductor nanowires has been growing over the past decade when the fabrication technology for Si-integrated circuits entered an advanced phase where the gate length of a field effect transistor (FET) shrank to a few tens of nanometers with the evolution of the technology. Fabrication of nanostructures to explore nanophotonics has also been a focus of interest for those who have been pursuing a single-photon source that can be used in optical communication systems that are expected to provide high degrees of reliability. Etching of semiconductor crystals has been widely used in conventional production processes to fabricate FETs and optical devices. However, eliminating damage or contamination created by etching on the crystal surface has become more difficult as device sizes have reduced. Compared to etching-based top-down methods of fabrication, the bottom-up method based on crystal growth is a counter approach to fabricating nanostructures without any concern for damage during fabrication. Wagner and Ellis reported the vapor-liquid-solid (VLS) growth of Si whiskers using Au as a catalyst [1] to form semiconductor nanowires in 1964. Since then, various nanowires comprised of Si [2, 3], Ge [2, 3], GaAs [4], InP [5], In2O3 [6], GaN [7], and ZnO [8] grown by VLS have been reported and the
%U http://www.hindawi.com/journals/jnt/2012/169284/