Charge-imaging field-effect transistor

Charge-imaging field-effect transistors (FETs) were fabricated from a GaAs/ AlGaAs heterostructure containing a near-surface two-dimensional electron g as. These FETs have quantum point contact geometries to minimize the size o f the channel and to improve the spatial resolution. The charge noise at T= 4.2 K has a 1/f behavior and reaches values <<1e/Hz(1/2) at 30 kHz. The spa tial resolution of the FET was measured at liquid He temperatures using a s canned probe microscope with a charged tip. The charge sensitivity of the F ET is confined to a disk with full width at half maximum 340 nm. These FETs are suitable for integration onto a GaAs/AlGaAs scanned probe microscopy c antilever. (C) 2001 American Institute of Physics.