Stochastic current switching in bistable resonant tunneling systems

Current-voltage characteristics of resonant-tunneling structures often exhibit intrinsic bistabilities. In the bistable region of the I-V curve one of the two current states is metastable. The system switches from the metastable state to the stable one at a random moment in time. The mean switching time τ depends exponentially on the bias measured from the boundary of the bistable region V_th. We find full expressions for τ (including prefactors) as functions of bias, sample geometry, and in-plane conductivity. Our results take universal form upon appropriate renormalization of the threshold voltage V_th. We also show that in large samples the switching initiates inside, at the edge, or at a corner of the sample depending on the parameters of the system.