Heterostructures in GaP-based free-standing nanowires on Si substrates

Vertical III-V compound semiconductor nanowires grown on Si(111) surfaces have been attracting interest for application to opto-electronic integrated circuits (OEICs). In nanowire growth, heterostructures in the axial and radial direction can be obtained by combining different materials with different growth conditions. These effects should make it possible to fabricate complicated and functional three-dimensional structures in a bottom-up manner. These advances should lead to new types of nanodevices. We describe the formation of several heterostructures using GaP-based nanowires on Si(111). The catalysts used were Au particles obtained from Au colloids. We obtained GaP/GaAs/GaP nanowires bent at thinned GaAs nodes, InP egg-like structures in GaP nanowires, core-multishell Ga(In)P/GaAs(or air-gap)/GaP nanowires with flat tops, and GaAs/AlInAs capped GaInAs nanowires for long-wavelength photon emission. These structures were successively grown on vertical GaP nanowires on Si(111) substrates.