The thermal stability of the oxygen precipitates in Czochralski silicon (Cz-Si) crystal with germanium doping has been investigated with rapid thermal annealing. It was found that the grown-in oxygen precipitates could be dissolved easily in germanium-doped Cz-Si (GCz-Si) than in conventional Cz-Si. After prolonged high-temperature thermal cycle, it was found that the germanium doping inclined to dramatically reduce the thermal stability of oxygen precipitates in Cz-Si crystal, either generated at low temperature (800 degrees C) or formed at high temperature (1000 degrees C). It is proposed that the germanium doping in Cz-Si could result in the oxygen precipitates with small size and plate shape, which reduce their thermal stability. (C) 2007 Elsevier B.V. All rights reserved.