The impact of Ge codoping on grown-in O precipitates in Ga-doped Czochralski-silicon

Abstract

a b s t r a c tThe intensity of the infrared absorption band at 1107 cm À 1 , related to interstitial oxygen (O i ) concentration, decreased as the Ge concentration increased in Ga and Ge codoped CZ-Si crystals. In contrast, the number of precipitates observed on the etched surfaces of CZ-Si wafers increased as the Ge concentration increased. From an energy dispersive X-ray (EDX) analysis, O was observed to be one of the major components of the precipitates. Moreover, Ge was found as one of the components in the precipitate observed on the heavily Ge (4 1 Â 10 18 cm À 3 ) codoped CZ-Si wafers. These results suggest that the grown-in O precipitates increase as the O i concentration decreases when the Ge concentration increases in the Si crystal. The Ge-vacancy (V) complex in the Si lattice probably acted as a heterogeneous nucleation center and may enhanced the grown-in O precipitates thereby reducing the dissolved O i concentration in the Si lattice.