Introduction of Ge into ULSIs has become increasingly attractive because of the higher carrier mobility of Ge. Here, the reactions between Ge oxide and Si substrate or SiH_4 in order to perform high-quality Ge epitaxial growth and atomic-order surface nitridation of Ge/Si_(0.5)Ge_(0.5)/Si (100) heterostructure by NH_3 are investigated. It is found that, by the adsorption of the Ge oxide on Si(100) surface, pure Ge and Si oxide are formed on the surface even at 400 °C, and that, by SiH_4 treatment at 350°C, the amount of the oxidized Ge decreases and Si oxide is formed on the Ge layer. On the nitridation of the heterostructure, it is found that N atoms diffuse through nm-order thick Ge layer into Si_(0.5)Ge_(0.5)/Si(100) substrate and form Si nitride even at 500 °C. These results demonstrate the capability of CVD technology for atomically controlled processing of group Ⅳ semiconductors for ultra-large-scale integration.
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