Abstract
We use Scanning Gate Microscopy to study electron transport through an open, gate-defined resonator in a Ga(Al)As heterostructure. Raster-scanning the voltage-biased metallic tip above the resonator, we observe distinct conductance modulations as a function of the tip-position and voltage. Quantum mechanical simulations reproduce these conductance modulations and reveal their relation to the partial local density of states in the resonator. Our measurements illustrate the current frontier between possibilities and limitations in imaging the local density of states in buried electron systems using scanning gate microscopy.
Highlights
Scanning gate microscopy (SGM) provides a unique mean to investigate local properties of carrier transport in semiconductor nanostructures based on buried two-dimensional electron gases (2DEG) [1,2]
The scanning gate measurements in the open resonator structure presented in this Letter reveal distinct conductance modulations as a function of the cavity-gate voltage Vcav, the tip position, and the tip voltage Vtip
Numerical simulations using the KWANT package [43] substantiate the premise that these conductance modulations are related to the cavity modes
Summary
Scanning gate microscopy (SGM) provides a unique mean to investigate local properties of carrier transport in semiconductor nanostructures based on buried two-dimensional electron gases (2DEG) [1,2] This imaging technique uses the capacitive coupling between the voltage-biased metallic tip scanned above the sample surface and the electrons in the 2DEG. Quantum-mechanical simulations exhibit a good qualitative agreement with the experimental data and display a correlation between the conductance modulations in the SGM conductance maps and the partial local density of states in the cavity. These results show that weakly invasive SGM provides a tool for measuring direct signatures of the partial local density of states in large two-dimensional electronic structures
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