INFLUENCE OF QUASI-LOCAL STATES OF IN ON DEFECT FORMATION IN PBTE

The effect of amphoteric impurity states, which are partially filled w ith electrons, on defect formation in narrow-gap semiconductors is inv estigated for the example of In impurity and PbTe. On the basis of exp erimental data on self-compensation in the system PbTe:In,Te-ex, the d ependence of the density n(upsilon) of compensating lead vacancies on the In impurity content in the samples is calculated in a thermodynami c theory. The calculations indicate that the energy position of the am photeric level strongly influences the character of the defect-formati on process. Not only can the density of compensating defects increase (self-compensation phenomenon), but also their density can be independ ent and n(upsilon) can even decrease as the impurity concentration inc reases. (C) 1996 American Institute of Physics.