Tetrasilane and digermane for the ultra-high vacuum chemical vapor deposition of SiGe alloys

Publication date: 1 April 2016
Source:Thin Solid Films, Volume 604
Author(s): John Hart, Ramsey Hazbun, David Eldridge, Ryan Hickey, Nalin Fernando, Thomas Adam, Stefan Zollner, James Kolodzey
Tetrasilane and digermane were used to grow epitaxial silicon germanium layers on silicon substrates in a commercial ultra-high vacuum chemical vapor deposition tool. Films with concentrations up to 19% germanium were grown at temperatures from 400°C to 550°C. For all alloy compositions, the growth rates were much higher compared to using mono-silane and mono-germane. The quality of the material was assessed using X-ray diffraction, atomic force microscopy, and spectroscopic ellipsometry; all indicating high quality epitaxial films with low surface roughness suitable for commercial applications. Studies of the decomposition kinetics with regard to temperature were performed, revealing an unusual growth rate maximum between the high and low temperature deposition regimes.