On the determination of the diffusion length of charge carriers in the absorber material of 2D mercury-cadmium-tellurium-based focal-plane-array detectors from spot-scan profiles

Using the Monte Carlo method, we studied the influence of the lateral transport of photogenerated charge carriers along diodes on the result of determining, from measured spot-scan profiles, the bulk length of charge- carrier diffusion in the absorber material of focal-plane diode arrays. An estimate of the corresponding inaccuracy in determining this length is given. The numerical simulation was carried out using the example of focal-plane diode arrays with 30 $\mu$m pitch, 14 $\times$ 14-$\mu$m diode size, and 6-$\mu$m thick absorber layer. The range of examined values of the bulk diffusion length of charge carriers in the absorber material was from 5 to 30 $\mu$m. It is shown that the analysis performed makes it possible to describe the fine structure of spot-scan profiles at both high and low levels of diode photocurrents. It was found that the method used yields the values of the bulk diffusion length of charge carriers increased compared to the true ones by approximately 20–25%.