AN ELECTROSTATIC SI E-GUN AND A HIGH-TEMPERATURE ELEMENTAL B SOURCE FOR SI HETEROEPITAXIAL GROWTH

In this paper we present two kind of sources used in Si MBE growth: a Si source where an electron beam is electrostatically deflected onto a Si rod and a high temperature B source to be used for p-doping. Both sources have been designed and constructed at IESS. The Si source is c onstituted of a Si rod mounted on a 3/4 '' flange with high-voltage co nnector. A W filament held at high voltage (up to 2000 V) is heated by direct current. Electrons from the filament are electrostatically foc used onto the Si rod which is grounded, This mounting allows a minimum heating dispersion and no contamination, because the only hot objects are the Si rod and the W filament which is mounted in such a way that it cannot see the substrate, Growth rates of 10 Angstrom/min on a sub strate at 20 cm from the source have been measured. Auger and LEED hav e shown no contamination. The B source is constituted of a graphite bl ock heated by direct current. A pyrolitic graphite crucible put in the graphite heater contains the elemental B, The cell is water cooled an d contains Ta screens to avoid heat dispersion, It has been tested up to a temperature of 1700 degrees C. P-doped Si1-xCex layers have been grown and B concentration has been measured by SIMS, A good central an d reproducibility has been attained.