CARRIER LIFETIME MEASUREMENTS BY MICROWAVE PHOTOCONDUCTIVE DECAY METHOD AT LOW INJECTION LEVELS

The minority carrier lifetime of Si wafers has been measured at very l ow injection levels by employing a newly developed microwave photocond uctive decay (mu-PCD) technique. It is found that the effective lifeti me is dramatically increased for the case of p-type Si when the inject ion level is reduced to two orders of magnitude less than the equilibr ium value. In contrast to this, the n-type wafer lifetime remains almo st un-changed even upon lowering the injection level. Also, it is show n that the different contamination levels of Fe in Si wafers are clear ly discriminated by the measured lifetime.