Magnetotransport measurements on freely suspended two-dimensional electron gases

Abstract

We present magnetotransport measurements on freely suspended two-dimensional electron gases from ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}/\mathrm{GaAs}$ heterostructures. The technique to realize such devices relies on a specially molecular beam epitaxy grown $\mathrm{GaAs}/{\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$-heterostructure, including a sacrificial layer. We fabricated simple mini-Hall-bars as well as quantum cavities and quantum dot systems. We find well-pronounced Shubnikov--de Haas oscillations and observe commensurability resonances, allowing characterization of the electron gas in these 100-nm thin membranes.