Fabrication of Single-Electron Transistor Composed of a Self-Assembled Quantum Dot and Nanogap Electrode by Atomic Force Microscope Local Oxidation

In this study, we employed the atomic force microscope (AFM) local oxidation method to fabricate a nanogap electrode and align it with a single self-assembled InAs quantum dot (QD). The nanogap electrode, with an Al/Al-oxide/Al structure, was fabricated in situ right on top of a randomly positioned self-assembled QD, to yield a single-electron transistor (SET) device. The fabricated transistor shows a clear Coulomb blockade effect, indicating that a high-quality SET can be fabricated reliably by this method, even in the case of a self-assembled QD.