Simplified model of dislocations as a SRH recombination channel in the HgCdTe heterostructures

A simple model of dislocation band formed by the dangling bonds of atoms of a dislocation core has been presented and discussed. The parameters of this model, which could be verified experimentally, are the average energy of the dislocation band states and the average length of the dislocation as well as electron and hole emission coefficients. The formulas for statistical functions of distribution of electrons in these bands have been derived. Next, we have developed a model of the SRH recombination channel connected with dislocation band states and we have adopted it to determine an effective lifetime of electron–hole pairs including effect of dislocations. In addition, influence of the tunnelling current from and into dislocation band has been considered, which seems to be a serious issue in reverse biased heterostructue HgCdTe photodiodes. Exemplary results of calculations for HgCdTe structures show that the number of the ionized atoms of the dislocation cores is of the order of a few percent. Moreover, the electric potential distributions in the area of the dislocation core has been calculated. Some experimental I–V characteristics of near room temperature HgCdTe devices are presented and compared with numerical simulations, what indicate on contribution of dislocations as a SRH recombination channel.