Magnetoconductivity (σ) measurements on an n-type molecular beam epitaxy grown epitaxial layer and on a bulk liquid encapsulated Czochralski grown undoped semi-insulating GaAs samples were performed for magnetic fields (B) up to 21 T at 4.2 K. To enable current measurements in a wide range of B both samples were permanently illuminated with a band-to-band light. It is shown that for sufficiently high magnetic fields σ(B) dependence is the same for both materials. This result underlines a role of scattering by long-range fluctuations of the electrostatic potential in high-quality n-GaAs in quantizing magnetic fields.
This paper presents an overview of scanning-gate microscopy applied to the imaging of electron transport through buried semiconductor nanostructures. After a brief description of the technique and of its possible artifacts, we give a summary of some of its most instructive achievements found in the literature and we present an updated review of our own research. It 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. In all of the given examples, we emphasize how a local-probe approach is able to shed new, or complementary, light on transport phenomena which are usually studied by means of macroscopic conductance measurements.
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