Abstract: A single crystal is pulled to a length at which the beginning of the body of the single crystal is assumed sufficiently to have been cooled down to a temperature below 1000.degree. C.; then the single crystal being pulled is detached from the molten silicon by pulling it at a speed high enough to cut it out from the molten silicon. Then oxygen precipitation heat-treatment is performed on the single crystal to locate the portion of AOP. AOP arises at the boundary of grown-in defects being formed zone while the single crystal passes through 1100.degree. C., and the position is at about 1100.degree. C. immediately before, detaching the single crystal out from the molten silicon. Therefore, the position at temperature 1100.degree. C. in the single crystal immediately before detaching the single crystal out from the molten silicon are known, then the temperature distributions of the single crystal immediately before detaching it out from the molten silicon can be decided easily.

Abstract: When the silicon single crystal is pulled up, the nucleation rate of the void cluster is obtained from the forming energy of the cluster of the vacancies in the silicon single crystal. The growth shrinkage of the cluster is obtained basing on the deviation of the flowing-into amount to the cluster of the vacancies and the self-interstitials, and the pulling-up speed or the temperature distribution of the furnace is modified to inhibit the growth of the cluster so as to inhibit the grown-in defects of the silicon single crystal.

Abstract: In the manufacture of a single crystal using a semiconductor single-crystal pulling apparatus equipped with a radiation screen, the time of passage of the single crystal through the high-temperature region of 1050.degree. C. and above is made to be long and the time of passage of the single crystal through the temperature region of about 900.degree. C.-500.degree. C. is made to be short. The semiconductor single-crystal pulling apparatus is so constructed that a radiation screen comprises an upper screen of 3-layer construction consisting of a heat-insulating member made of graphite or ceramics fiber clad with outer members made of graphite and a lower screen 3 of single-layer construction made of graphite, quartz or fine ceramics. Radiant heat from the molten liquid heats the lower part of single crystal as it passes through lower screen, thereby prolonging its period of passage through the high-temperature region.