Observation of single-electron transport in a Zn_0.8Mg _0.2O/ZnO coaxial heterostructure nanorod

Coaxial Zn_0.8Mg_0.2O/ZnO hetrostructure semiconducting nanorods with different band gaps were fabricated on oxide-layer-covered Si substrates by using catalyst-free metal-organic vapor-phase epitaxy. The electrical conduction of nanorods with Ti/Au Schottky-contact electrodes, taken at various temperatures down to 50 mK, revealed a Coulomb-blockade behavior, pointing a multiple quantum-dot structure existing in the ZnO nanorod core or in the Zn_0.8Mg_0.2O cylindrical shell over a wide range of gate voltages. These characteristics, transformed into single-dot ones at high positive gate voltages. This study confirms, by electrical conduction measurements, the formation of a coaxial heterojunction structure between materials of two different band gaps and provides a possibility for utilizing the structure for three-terminal device applications.