Erasable electrostatic lithography for quantum components.

Abstract

Quantum electronic components--such as quantum antidots and one-dimensional channels--are usually defined from doped GaAs/AlGaAs heterostructures using electron-beam lithography or local oxidation by conductive atomic force microscopy. In both cases, lithography and measurement are performed in very different environments, so fabrication and test cycles can take several weeks. Here we describe a different lithographic technique, which we call erasable electrostatic lithography (EEL), where patterns of charge are drawn on the device surface with a negatively biased scanning probe in the same low-temperature high-vacuum environment used for measurement. The charge patterns locally deplete electrons from a subsurface two-dimensional electron system (2DES) to define working quantum components. Charge patterns are erased locally with the scanning probe biased positive or globally by illuminating the device with red light. We demonstrate and investigate EEL by drawing and erasing quantum antidots, then develop the technique to draw and tune high-quality one-dimensional channels. The quantum components are imaged using scanned gate microscopy. A technique similar to EEL has been reported previously, where tip-induced charging of the surface or donor layer was used to locally perturb a 2DES before charge accumulation imaging.