Multiple layer local oxidation for fabricating semiconductor nanostructures

TL;DR

This paper presents a novel fabrication method using local oxidation with a scanning force microscope to create highly tunable coupled semiconductor nanostructures, including quantum dots, with high quality demonstrated through Coulomb blockade experiments.

Contribution

It introduces a new technique combining direct oxidation of GaAs and Ti films to produce tunable, high-quality coupled nanostructures with integrated charge readout.

Findings

Successful fabrication of a four-terminal quantum dot.

Realization of a double quantum dot system with charge readout.

Demonstration of high-quality structures via Coulomb blockade.

Abstract

Coupled semiconductor nanostructures with a high degree of tunability are fabricated using local oxidation with a scanning force microscope. Direct oxidation of the GaAs surface of a Ga[Al]As heterostructure containing a shallow two-dimensional electron gas is combined with the local oxidation of a thin titanium film evaporated on top. A four-terminal quantum dot and a double quantum dot system with integrated charge readout are realized. The structures are tunable via in-plane gates formed by isolated regions in the electron gas and by mutually isolated regions of the Ti film acting as top gates. Coulomb blockade experiments demonstrate the high quality of this fabrication process.