Numerical aspects on the simulation of I-V characteristics and switching times of resonant tunneling diodes

The development of a more accurate numerical scheme for simulating double-barrier semiconductor structures has highlighted sensitivities of the computational results to numerical parameters for the different approximation schemes. In numerically evaluating the time evolution of the Wigner function, a second-order differencing scheme (SDS) was used instead of a simple up/down wind differencing scheme (UDS). In our investigations of the numerical aspects of these schemes, we have found: (a) the proximity of the ‘‘computational box’’ boundaries to the double-barrier region affects the peak-to-valley ratio of the I-V curve and the value of the bias at peak current; (b) the peak-to-valley ratio is larger for the SDS than it is for the UDS; (c) the current at the resonant bias for SDS is larger than that calculated using UDS; (d) the rise in the current in the nonresonant regions for both SDS and UDS is dependent on how the bias is applied; and (e) the presence of an accumulation of electrons in the first heterojunction of the first barrier provides a closer correspondence between simulation and experimentally observed I-V.