Equivalent circuit for the sample
For a numerical treatment the (linear) sample is divided into discrete elements with respect to the x-coordinate.
Each element of the sample consists of the resitors Rn and Rp, representing the n- and p-layers, and a diode Dpn,
representing the barriers between the layers. The lateral voltage drops can be calculated by use of the local resistors
Rn and Rp, whereas the leakage current IB results from the bias voltage of the diode Dpn, which is determined by
the local potential modulation V(x). The upper part of the figure shows the
equivalent circuit of the sample and the lower part indicates the current redistribution between the layers. Due to
the greater potential modulation near the positive contact the net leakage current between the layers leads to a
redistribution of the n-current from the n-layer to the p-layers wheras the smaller potential modulation near the
negative contact allows the current, which is flowing in the p-layers, to be redistributed to the n-layer again. The
diode DC on the right side of the circuit represents a current channel for a break-through between the p-layers and
the positive contact.
For a numerical solution two different situations will be considered: steady state conditions in order to obtain I(V)-
curves at different background generation rates g(x) and time dependent conditions for the simulation of the time
dependent evolution of the photoconductive signal, which is the temporal evolution from one steady state condition
to another. In both cases the continuity equation plays a key role for the calculation of the current distributions In(x)
and Ip(x).
For more detailed information