Scanning-gate-induced effects and spatial mapping of a cavity

TL;DR

This paper investigates how scanning gate microscopy influences a two-dimensional electron gas, focusing on tip-induced potentials, cavity formation, conductance quantization, and electrostatic screening effects.

Contribution

It provides methods to estimate tip-induced potential size, explores cavity behavior under different gate voltages, and discusses electrostatic screening in a comprehensive manner.

Findings

Tip-induced potential size can be estimated accurately.

Conductance quantization leads to complex fringe patterns.

Electrostatic screening significantly affects the cavity behavior.

Abstract

Tailored electrostatic potentials are the foundation of scanning gate microscopy. We present several aspects of the tip-induced potential on the two-dimensional electron gas. First, we give methods on how to estimate the size of the tip-induced potential. Then, a ballistic cavity is formed and studied as a function of the bias-voltage of the metallic top gates and probed with the tip-induced potential. It is shown how the potential of the cavity changes by tuning the system to a regime where conductance quantization in the constrictions formed by the tip and the top gates occurs. This conductance quantization leads to a unprecedented rich fringe pattern over the entire structure. Finally, the effect of electrostatic screening of the metallic top gates is discussed.