Decay of metastable current states in one-dimensional resonant tunneling devices

Current switching in a double-barrier resonant tunneling structure is studied in the regime where the current-voltage characteristic exhibits intrinsic bistability, so that in a certain range of bias two different steady states of current are possible. Near the upper boundary V_th of the bistable region the upper current state is metastable, and because of the shot noise it eventually decays to the stable lower current state. We find the time of this switching process in strip-shaped devices, with the width small compared to the length. As the bias V is tuned away from the boundary value V_th of the bistable region, the mean switching time τ increases exponentially. We show that in long strips ln τ∝(V_th−V)^5∕4, whereas in short strips ln τ∝(V_th−V)^3∕2. The one-dimensional geometry of the problem enables us to obtain analytically exact expressions for both the exponential and the prefactor of τ. Furthermore, we show that, depending on the parameters of the system, the switching can be initiated either inside the strip, or at its ends.