Scanning single-electron transistor microscopy: Imaging individual charges

We describe the single-electron transistor scanning electrometer (SETSE), a novel scanned probe microscope capable of mapping static electric fields and charges with submicron (100nm) spatial resolution and fractional electron charge sensitivity (0.01e). The active sensing element of the SETSE is a single-electron transistor fabricated at the end of a sharp glass tip. Images of the surface electric fields of a GaAs/AlGaAs heterostructure sample taken before and after brief exposures to light show individual photoionized charge sites as well as 100nm length scale fluctuations in the dopant and surface charge distribution. We also describe SETSE images and measurements of depleted regions, local capacitance, band bending, and work functions at submicron length scales on the surface of this model semiconductor device. © 1998 Elsevier Science B.V. All rights reserved.