Gap deep defect states in narrow-gap semiconductors

The role of deep defect states in recombination processes of narrow-gap IV-VI semiconductors is discussed. Earlier several defect states in the gap of IV-VI semiconductors were revealed. Estimations have shown the defect levels nearer to c-band presumably are connected with metal-rich microinclusions by diameter about 1300 Angstrom These metal-rich inclusions are the result of low metal vacancies enthalpy formation (Deltav approximate to0.35 eV). These defect states seem are arising at the inclusions and semiconductor matrix boundaries. The density and the diameter of these intrinsic metal microinclusions were calculated from the results of magnetic succeptibility by SQUID-magnetometry experiments in the 1.7-20 K temperature region. The levels above the v-band, with the density of states about 3 times lower compared to density of states below c-band, seem to be connected with Te-rich microclusters. The enthalpy of Te-vacancies formation is about 0.45 eV. Experiments and estimations fulfilled on defect levels position and concentrations allow to explain the experiments on band-to-band recombination, photoconductivity and relaxation measurements, stimulates recombination between defect level and v-band, and some nonlinear effects in these semiconductors.