J. Phys. IV France 05 (1995) C5-1165-C5-1172
Low-Temperature Epitaxial Growth Mechanism of Si1-xGex Films in the Silane and Germane ReactionsJ. Murota1, Y. Takasawa2, H. Fujimoto3, K. Goto4, T. Matsuura1 and Y. Sawada1
1 Laboratory for Electronic Intelligent Systems, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-77, Japan
2 On leave from Kokusai Electric Co., Ltd., Toyama Works, 2-1 Yasuuchi, Yatsuomachi, Neigun, Toyama 939-23, Japan
3 On leave from Miyagi OKI Electric Co., Ltd., 1 Okinodaira, Ohiramura, Kurokawagun, Miyagi 981-36, Japan
4 DC Research Fellow of the Japan Society for the Promotion of Science
Low-temperature epitaxial growth of undoped and doped Si1-xGex films on the Si(100) surface at 550°C was investigated under the cleanest possible reaction environment of SiH4, GeH4 and H2 with the PH3 or B2H6 addition using an ultraclean hot-wall low-pressure chemical vapour deposition (LPCVD) system. The SiH4 and GeH4 reaction rates are expressed by the Langmuir-type rate equation, assuming that one SiH4 or GeH4 molecule is adsorbed at a single adsorption site, according to the Langmuir's adsorption isotherm, and decomposes there. It is found that the SiH4 and GeH4 adsorption rate constants become larger at the bond site of the Si-Ge pair than those at the others, while the SiH4 surface reaction rate constant becomes the largest at the bond site of the Ge-Ge pair. With the PH3 and B2H6 addition, the incorporation rate of P and B increased proportionally and was higher with a higher Ge fraction x in the film. This was explained by the increase of the free site density and the difference of free site materials according to the Langmuir-type rate equation. In the case of P doping, it is found that electrically inactive P is formed with high Ge fractions.
© EDP Sciences 1995