Incorporation of boron into UHV/CVD-grown germanium-silicon epitaxial layers
Doping of UHV/CVD-grown germanium-silicon epitaxial layers by diborane is reported. The boron concentration is linear in diborane flow rate and is consistent with a surface reaction mechanism in which two surface sites are required for adsorption. The sticking coefficient of diborane on a bare silicon or germanium-silicon surface is found to be about 1.2 × 10-2. Abrupt retrograde profiles can be grown successfully provided a pause is introduced before growing more lightly doped layers.