On the imaging of electron transport in semiconductor quantum structures by scanning-gate microscopy: successes and limitations

TL;DR

This paper reviews scanning-gate microscopy for imaging electron transport in semiconductor quantum structures, highlighting its successes, specific applications to quantum rings, and discussing its limitations and potential artefacts.

Contribution

It provides a comprehensive overview of the technique's achievements and critically analyzes its limitations based on recent research and the authors' own experiments.

Findings

Successful imaging of GaInAs quantum rings in different regimes

Identification of artefacts and limitations in scanning-gate microscopy

Emphasis on careful interpretation of conductance maps

Abstract

This paper presents a brief review of scanning-gate microscopy applied to the imaging of electron transport in buried semiconductor quantum structures. After an introduction to the technique and to some of its practical issues, we summarise a selection of its successful achievements found in the literature, including our own research. The latter focuses on the imaging of GaInAs-based quantum rings both in the low magnetic field Aharonov-Bohm regime and in the high-field quantum Hall regime. Based on our own experience, we then discuss in detail some of the limitations of scanning-gate microscopy. These include possible tip induced artefacts, effects of a large bias applied to the scanning tip, as well as consequences of unwanted charge traps on the conductance maps. We emphasize how special care must be paid in interpreting these scanning-gate images.