Low Temperature Electrostatic Force Microscopy of a Deep Two Dimensional Electron Gas using a Quartz Tuning Fork

TL;DR

This paper demonstrates a method for measuring electrostatic potentials of a deeply buried two-dimensional electron gas at ultra-low temperatures using a quartz tuning fork in an electrostatic force microscopy setup, revealing quantum oscillations.

Contribution

It introduces a novel application of quartz tuning fork oscillators for electrostatic force microscopy of buried 2DEGs at very low temperatures and high magnetic fields.

Findings

Successful detection of Shubnikov de Haas oscillations at over 500 nm tip-2DEG separation

Demonstration of high sensitivity of quartz tuning fork as a force sensor in this context

Measurement of electrostatic potentials in a deeply buried 2DEG structure

Abstract

Using an ultra-low temperature, high magnetic field scanning probe microscope, we have measured electric potentials of a deeply buried two dimensional electron gas (2DEG). Relying on the capacitive coupling between the 2DEG and a resonant tip/cantilever structure, we can extract electrostatic potential information of the 2DEG from the dynamics of the oscillator. We present measurements using a quartz tuning fork oscillator and a 2DEG with a cleaved edge overgrowth structure. The sensitivity of the quartz tuning fork as force sensor is demonstrated by observation of Shubnikov de Haas oscillations at a large tip-2DEG separation distance of more than 500 nm.