J. Phys. IV France 03 (1993) C3-427-C3-432
Low-temperature epitaxial growth of in-situ B-doped Si1-xGex filmsJ. MUROTA1, F. HONMA2, T. YOSHIDA1, K. GOTO1, T. MAEDA3, K. AIZAWA4 and Y. SAWADA1
1 Laboratory for Microelectronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980, Japan
2 On leave from Miyagi OKI Electric Co., Ltd., 1 Okinodaira, Ohiramura, Kurokawagun, Miyagi 981-36, Japan
3 On leave from Kokusai Electric Co., Ltd., Toyama Works, 2-1 Yasuuchi, Yatsuomachi, Neigun, Toyama 939-23, Japan
4 On leave from Sumitomo Metal Mining Co., Ltd., Central Research Lab., Ichikawa 272, Japan
We report in-situ boron doping of Si1-xGex films epitaxially grown on Si(100) by low-pressure chemical vapour deposition (LPCVD) process. The experiments are performed in an ultraclean hot-wall system using ultra-pure SiH4-GeH4-H2-B2H6 gas mixtures. The incorporation rate of B was proportional to the B2H6 partial pressure and was larger for Ge-rich films. It was proposed that the increase in B incorporation rate with increasing Ge fraction was caused by the larger surface adsorption rate of B-hydride on Ge atoms than on Si atoms. Since the incorporation rate of B increased with exposure time of B2H6 during Si1-xGex deposition at early stage, it was suggested that B doping was limited by the B-hydride adsorption rate. Hall measurements showed that carrier concentration was equal to B concentration in the range 3x1017-2x1020 cm-3, regardless of the Ge fraction, and Hall mobility passed through a minimum value for Si0.75Ge0.25 films regardless of the film thickness.
© EDP Sciences 1993