Triangulating tunneling resonances in a point contact

TL;DR

This paper demonstrates a method to identify and locate tunneling resonances in silicon devices with nanometer precision using capacitance triangulation and electrostatic simulations, advancing understanding of donor-based quantum transport.

Contribution

It introduces a capacitance triangulation technique combined with simulations to pinpoint the location of tunneling resonances in silicon devices, distinguishing donor-related resonances from disorder effects.

Findings

Capacitance measurements identify resonance locations with nanometer accuracy.

Simulations correlate capacitance data with specific spatial confinement potentials.

Resonant tunneling through single donors can be distinguished from disorder-induced effects.

Abstract

We observe resonant tunneling in silicon split gate point contacts implanted with antimony and defined in a self-aligned poly-silicon double gate enhancement mode Si-MOS device structure. We identify which resonances are likely candidates for transport through the antimony donor as opposed to unintentional disorder induced potentials using capacitance triangulation. We determine the capacitances from the resonant feature to each of the conducting gates and the source/drain two dimensional electron gas regions. In our device geometry, these capacitances provide information about the resonance location in three dimensions. Semi-classical electrostatic simulations of capacitance, already used to map quantum dot size and position, identify a combination of location and confinement potential size that satisfy our experimental observations. The sensitivity of simulation to position and size allow us to triangulate possible locations of the resonant level with nanometer resolution. We discuss our results and how they may apply to resonant tunneling through a single donor.