Abstract
It is established that the surface state is one of the most important mechanisms limiting the performance of photoconductors. In a previous work, we have presented the theoretical platform of surface state model exhibiting the analysis of the space charge region at the free surface of semiconductors. To know that recombination effects directly influence the quantum efficiency of detector, the dependence of some detector parameters on surface defect densities and the comparison of this model with experimental data of responsivity are evaluated. The present papers use this model to explore the dependence of surface parameters on signal, noise and detectivity. The results of the model are compared with the experimental results for p-PbS case.