NONLINEAR OPERATION OF A FINITE-SIZE TUNNEL JUNCTION BETWEEN 2D ELECTRON-SYSTEMS

A nonlinear regime of electron tunneling into double quantum wells wit h independent contacts to each well is investigated theoretically. The nonlinear current-voltage response in these systems takes place when the voltage V applied to the contacts exceeds the tunneling resonance width. It is found that such a nonlinearity acquires essentially new f eatures when the length of the tunneling area is comparable with the s quare root of the ratio of the averaged in-plane conductivity of the e lectrons to the resonance tunneling conductance. Under these condition s, the local interlayer voltage v does not coincide with V and depends on the in-plane coordinate x. The local tunneling conductance also de pends on x in the nonlinear regime. This dependence creates a positive feedback, which leads to a bistable behavior of the system (two stabl e patterns of the local voltage at a fixed V). The bistability is refl ected by Z-like regions of the current-voltage characteristics. (C) 19 98 Academic Press Limited.