Proceedings of the Ninth European Conference on Chemical Vapour Deposition

J. Phys. IV France 03 (1993) C3-427-C3-432
DOI: 10.1051/jp4:1993359

Low-temperature epitaxial growth of in-situ B-doped Si_1-xGe_x films

J. MUROTA¹, F. HONMA², T. YOSHIDA¹, K. GOTO¹, T. MAEDA³, K. AIZAWA⁴ and Y. SAWADA<sup>1

1</sup>  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

Abstract
We report in-situ boron doping of Si_1-xGe_x 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 Si_1-xGe_x 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 Si_0.75Ge_0.25 films regardless of the film thickness.

© EDP Sciences 1993