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

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.

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