RECORD HIGH RECOMBINATION LIFETIME IN OXIDIZED MAGNETIC CZOCHRALSKI SILICON

This letter demonstrates that recombination lifetimes in excess of 5 ms can be achieved in the oxidized magnetic Czochralski (MCZ) silicon by a combination of high-purity crystal growth, proper cleaning and oxidation conditions. Lifetime studies were conducted at room temperature on as-grown as well as oxidized 2000 OMEGA cm low oxygen (approximately 5 ppm) MCZ silicon by an injection sensitive, contactless photoconductive decay technique with controlled injected carrier densities up to 10(17) cm-3. Record Shockley-Read-Hall lifetimes of 8.5 and 6.6 ms were achieved in the as-grown and oxidized MCZ wafers, respectively. However, oxidized Czochralski (CZ) silicon with 14.2 ppm oxygen gave lifetime of only 200-mu-s due to much higher concentrations of as-grown and process-induced defects. Lifetime versus injection level analysis gave ambipolar Auger recombination C coefficient of 1.1 X 10(-30) (+/- 9%) cm6 s-1 before and after the oxidation in both MCZ and CZ silicon. Unlike the C coefficient, the B coefficient (radiative band-to-band + trap-assisted Auger) in low-oxygen MCZ silicon was found to be four times smaller than the value in high oxygen CZ silicon.