COPPER IMPURITIES AND THEIR ANNEALING BEHAVIOR IN FZ SILICON

The electrical activity of copper as well as its annealing behaviour i n p-type 10 OMEGAcm FZ silicon substrate are studied by means of four- point probe and lifetime measurements. While copper concentration in t he range 10(15) to 10(16) cm-3 has little or no effect on the active c arrier concentration of the material, it has a devastating effect on t he lifetime of minority carriers by the formation of deep-level traps. The analysis of our results shows that only a small fraction of the c opper impurity atoms present form this deep-level defect. In this impu rity concentration range, copper does not seem to form complexes with the usual p-type impurity in silicon. The possible mechanism of defect recovery under time dependent annealing is discussed in the light of improved lifetime values without change in the resistivity values of c opper contaminated specimens.