Electrical Properties of Silver Impurities and their Annealing Behaviour in p-Type Fz Silicon

Overview & Synopsis

The electrical activity of silver as well as its annealing properties in $10~\Omega$ cm p-type Fz silicon substrate are studied by means of the four-point probe and minority carrier lifetime measurements. Silver atom concentration in the range 1014 to 1015 cm-3 consistently showed a donor type behaviour in the material and its presence led to a reduction of up to two orders of magnitude in the lifetime of minority carriers by the formation of deep-level traps. Isochronal annealing of silver contaminated specimens showed some gettering of the Ag impurities with resulting temperature dependent changes in the resistivity as well as the minority carrier lifetime values. Analysis of our results shows that a large fraction of the silver impurity atoms present forms the deep level defects and both the deep- and donor-levels appear to originate from the same source.