Influence of Carbon in In-situ Carbon-Doped SiGe Films on Si(001) Substrates on Epitaxial Growth Characteristics

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Carbon doped SiGe (SiGe:C)/Si(001) heterostructure were grown by reduced pressure chemical vapor deposition using silane, germane and methylsilane as a source of Si, Ge, and C, respectively. We performed a systematic experiment of growth of SiGe:C and carried out measurements to determine the surface roughness and occupation sites of carbon atoms as functions of C source flow, Ge concentration, growth temperature and growth rate. Ge concentration range was from 0 to 23.0%. Growth temperature was 575 to 625 °C. The range of Growth rate was between 1.5 and 4.3 Å/s. These SiGe:C analyzed by atomic force microscopy (AFM), secondary ion mass spectrometry (SIMS), high-resolution X-ray diffraction (HR-XRD) and cross-sectional transmission electron microscopy (TEM). Total C compositions did not depend on growth temperature with the constant Ge concentration and with SiH3CH3 flow ratio. Surface roughness of SiGe:C with high Ge concentration increased with the increase of C source gas flow. Interstitial C concentration in SiGe:C films with rough surface increased with the increase of C source gas flow. The roughness of SiGe:C layer grown constant C gas source flow ratio decreased for low growth temperature and/or faster growth rate. From these results, we revealed that the mechanism of defect formation with localized C as the cause of rough. The excess migration can suppress surface roughness.
2010-04-25