Quenching of luminescence in semiconductors by charged defects

Charged point defects and dislocations create internal electric fields that can prevent the binding of carriers to luminescent centres such as N in GaP. The authors calculate the distribution of fields present in a semiconductor and its effect on the lifetime of an electron trapped at a localised impurity. The results show a decrease in the fraction of effective luminescent centres with increasing concentration of ionised donors and acceptors. Both unscreened dislocations and those with a compensating atmosphere of oppositely charged point defects are considered and the calculations show dark regions around them, as observed.