Mediation effect of sub‐monolayer carbon on interfacial mixing in Ge growth on Si(100)

Abstract

The mediation effect of carbon (C) on interfacial mixing in Ge growth was studied using C‐covered Si surface (Ge/C/Si) and C over thin Ge buffer layer (Ge/C/Ge/Si) systems. The samples were prepared by solid‐source molecular beam epitaxy system with electron beam gun for C sublimation and K‐cell for Ge evaporation. The interdiffusion at the interface and deterioration in crystallinity of Ge layer was evaluated by Raman spectroscopy and X‐ray diffraction, respectively. In the case of Ge/C/Si system, the interdiffusion of Si and Ge atoms was suppressed by more than 0.3 monolayer (ML)‐C depositions while crystallinity of Ge layer was deteriorates by the formation of Si‐C at the Si surface and the incorporation of C atoms in Ge layer. In the case of Ge/C/Ge/Si system, the crystallinity of Ge layer was maintained even at C coverage of a few MLs, however, the amount of C to suppress the Ge/Si interdiffusion was more than 3 ML. From the correlation between Ge crystallinity and surface roughness, Ge/C/Ge/Si structure is considered to be more effective to take advantage of C mediation. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)