Ultra-high-vacuum chemical vapor deposition of hetero-epitaxial Si1-x-yGexCy thin films on Si(001) with ethylene (C2H4) precursor as carbon source

Abstract The incorporation of substitutional carbon ( C sub ) in low-temperature epitaxial Si 1− x − y Ge x C y thin films using SiH 4 , GeH 4 and C 2 H 4 by ultra-high-vacuum chemical vapor deposition was investigated in this work. The Si 1− x − y Ge x C y alloys have been grown at a temperature range from 550 to 600 °C. The C sub content in Si 1− x − y Ge x C y increases with increasing C 2 H 4 partial pressure under the same SiH 4 and GeH 4 condition. The addition of excessive C 2 H 4 causes the degradation of Si 1− x − y Ge x C y crystallinity, surface roughening and the suppression of Ge incorporation. The C–C double bonds in C 2 H 4 were responsible for the highest percentage of C sub , only 0.2%, incorporated in Si 0.8− y Ge 0.2 C y . The Ge, B and C concentration were determined by secondary ion mass spectroscopy (SIMS). The total C atoms incorporation efficiency is ∼0.05. The maximum concentration of C sub in Si 1− x − y Ge x C y increases with the decrease of Ge content. In the ambient of hydride-based CVD at low-growth pressure and temperature, the presence of GeH 4 would impede the incorporation of C sub in Si 1− x − y Ge x C y /Si heterostructure using C 2 H 4 as C source.