  We present a theoretical analysis and numerical simulations of lateral
current density fronts in bistable resonant-tunneling diodes with Z-shaped
current-voltage characteristics. The bistability is due to the charge
accumulation in the quantum well of the double-barrier structure. We focus on
asymmetric structures in the regime of sequential incoherent tunneling and
study the dependence of the bistability range, the front velocity and the front
width on the structure parameters. We propose a sectional design of a structure
that is suitable for experimental observation of front propagation and discuss
potential problems of such measurements in view of our theoretical findings. We
point out the possibility to use sectional resonant-tunneling structures as
controllable three-terminal switches.
