Y. Kitagawara et al., EVALUATION OF OXYGEN-RELATED CARRIER RECOMBINATION CENTERS IN HIGH-PURITY CZOCHRALSKI-GROWN SI CRYSTALS BY THE BULK LIFETIME MEASUREMENTS, Journal of the Electrochemical Society, 142(10), 1995, pp. 3505-3509
Present day high-purity Czochralski(CZ)-grown Si crystals are characte
rized by the bulk carrier recombination lifetime measurements. The bul
k lifetime of the p-type as-grown Si with resistivity similar to 10 Om
ega-cm is found to be as high as 500 mu s for a CZ-Si crystal with [O-
i] > 10 ppma-JEIDA and as high as similar to 1 ms or even higher for a
low-oxygen CZ-Si crystal with [O-i] < 10 ppma-JEIDA. The as-grown bul
k lifetime is revealed to depend not only on resistivity under the fra
mework of the Shockley-Read-Hall (SRH) relation, but also on the oxyge
n concentration. The dominant recombination center of the as-grown cry
stal is found to be an SRH-type deep-level center which is considered
to be an oxygen-related defect complex. The complex is quenched easily
by a heat-treatment at a temperature as low as 650 degrees C. Effecti
ve density of a recombination center, existing after the 650 degrees C
heat-treatment in the p-type crystal, correlates well with the amount
of oxygen precipitation generated by a subsequent two-step heat proce
ss [800 degrees C for 4 h + 1000 degrees C for 16 h]. Thus the dominan
t recombination center after the 650 degrees C heat-treatment is consi
dered to be closely related to the oxygen precipitation nuclei toward
the subsequent precipitation formation heat process.