Predominant Si Doping through Au Catalyst Particles in the Vapor−Liquid−Solid Mode over the Shell Layer via the Vapor-Phase Epitaxy Mode of InAs Nanowires

Abstract

InAs semiconductor nanowires are expected to have applications in high-mobility nanoelectronics. Understanding the dopant distribution will be critical for the fabrication of high-performance devices based on nanowires. We study the n-type doping of InAs nanowires, using Si2H6 as a doping precursor, and clarify the predominant Si doping through Au catalyst particles. Using a series of segments in a single nanowire with a tapered shape and corresponding nanowire-channel field effect transistor characteristics, we show that the dopant atom incorporates predominantly via the Au-catalyzed vapor−liquid−solid mode, which accompanies the shell growth in the vapor-phase epitaxy mode. We determine the electrically active doping concentrations via the Au-catalyzed vapor−liquid−solid and vapor-phase epitaxy modes in the InAs nanowire to be 1.37 × 1018 and 1.57 × 1017 cm−3 under a In/Si source flow ratio of 600. This work developed a new method for the characterization of dopant distribution in semiconductor nanowires and the result provides more opportunities for the formation of modulation-doped core−shell nanowires and novel nanostructures.