Coulomb Blockade from the Shell of an InP-InAs Core-Shell Nanowire with a Triangular Cross Section

TL;DR

This study demonstrates the growth of InP-InAs core-shell nanowires with a triangular cross section that exhibit Coulomb blockade effects, indicating the formation of a long, single-electron quantum dot along the entire nanowire length.

Contribution

It introduces a novel growth method for InP-InAs nanowires with a triangular cross section that form a continuous quantum dot showing Coulomb blockade over their full length.

Findings

Nanowires exhibit Coulomb blockade at low temperatures.

Quantum dot spans the entire nanowire length.

InAs shell forms a single-electron quantum structure.

Abstract

We report on growth of InP-InAs core-shell nanowires and demonstration of the formation of single quantum structures, which show Coulomb blockade effect, over entire lengths of the nanowires. The core-shell nanowires are grown by a selective area growth technique via metal-organic vapor phase epitaxy. The as-grown core-shell nanowires are found to be of wurtzite crystals. The InP cores have a hexagonal cross section, while the InAs shell are grown preferentially on specific {1$\bar{1}$00} facets, leading to the formation of the core-shell nanowires with an overall triangular cross section. The grown core-shell nanowires are transferred on to a Si/SiO$_2$ substrate and then contacted with several narrow metal electrodes. Low-temperature transport measurements show the Coulomb-blockade effect. We analyze the measured gate capacitance and single electron charging energy of the devices and demonstrate that a quantum structure which shows the Coulomb blockade effect of a many-electron quantum dot is formed over the full length of a single core-shell nanowire and consists of the entire InAs shell in the nanowire.