The accurate predictions of THz quantum currents requires a new displacement current coefficient instead of the traditional transmission one

Modeling of quantum devices is still based on the original idea of Landauer that the macroscopic (DC) conductance of electron devices can be related to the (microscopic) transmission coefficient of electrons. In this paper we propose a simple model that captures the role of the particle and displacement currents in quantum electron devices working at THz by substituting the traditional transmission coefficient by a new displacement current coefficient. In particular, our model is used to compute the total current of a Resonant Tunnelling Diode (RTD) device under AC conditions. The new model, based on a time-dependent approach, is firstly shown to reproduce the DC behaviour of the Landauer model. Later on, at input frequencies higher than 500 GHz, large differences between the two models are observed. In particular, unexpected high frequency behavior is observed in simulations with an input signal up to 2 THz.