Effect of backgating on the field distribution in planar thin-film GaAs structures

The distribution of the electric field in planar film-substrate GaAs struct ures under backgating is considered. It is shown that backgating can make t he film exhibit a long-length region of a low-gradient electric field excee ding the threshold of N-type negative differential mobility, the magnitude of negative differential mobility in this region being high enough. At valu es of the film doping density and film thickness typical of GaAs transferre d-electron devices, this region can be as long as several tens of micromete rs. The underlying physical mechanism is discussed. (C) 2001 Elsevier Scien ce Ltd. All rights reserved.