Single-hole tunneling through a two-dimensional hole gas in intrinsic silicon

TL;DR

This paper demonstrates stable single-hole tunneling in a silicon-based quantum dot device, with detailed energy spectroscopy revealing Coulomb blockade effects and resonant tunneling phenomena.

Contribution

It presents a reproducible fabrication process and electrical characterization of silicon quantum dots exhibiting clear Coulomb blockade and resonant tunneling at cryogenic temperatures.

Findings

Reproducible Coulomb oscillations over a broad gate voltage range

Observation of Coulomb diamonds with charging energies of 5-10 meV

Detection of resonant tunneling lines through hole states

Abstract

In this letter we report single-hole tunneling through a quantum dot in a two-dimensional hole gas, situated in a narrow-channel field-effect transistor in intrinsic silicon. Two layers of aluminum gate electrodes are defined on Si/SiO$_2$ using electron-beam lithography. Fabrication and subsequent electrical characterization of different devices yield reproducible results, such as typical MOSFET turn-on and pinch-off characteristics. Additionally, linear transport measurements at 4 K result in regularly spaced Coulomb oscillations, corresponding to single-hole tunneling through individual Coulomb islands. These Coulomb peaks are visible over a broad range in gate voltage, indicating very stable device operation. Energy spectroscopy measurements show closed Coulomb diamonds with single-hole charging energies of 5--10 meV, and lines of increased conductance as a result of resonant tunneling through additional available hole states.