MF002800 - SEMI MF28 - Test Method for Minority Carrier Lifetime in Bulk Germanium and Silicon by Measurement of Photoconductivity Decay

Minority carrier lifetime is one of the essential characteristics of semiconductor materials. Many metallic impurities form recombination centers in germanium and silicon; in many cases, these recombination centers are deleterious to device and circuit performance. In other cases, the recombination characteristics must be carefully controlled to obtain the desired device performance.If the free carrier density is not too high, minority carrier lifetime is controlled by such recombination centers; however, because it does not distinguish the type of center present, a measurement of minority carrier lifetime provides only a nonspecific, qualitative test for metallic contamination in the material.When present in sufficient quantity, free carriers control the lifetime; thus, these test methods do not provide a reliable means for establishing the presence of recombination centers due to unwanted metallic or other non-dopant impurities when applied to silicon specimens with resistivity below