Interfacial strain and defects in Si (001) carbonisation layers for 3C-SiC hetero-epitaxy

摘要

The role of the temperature T_(intro) at which propane is introduced in the reactor during the heating ramp of the Si (001) carbonisation process is investigated. Mid-infrared polarized attenuated total reflectance spectra, cross sectional Transmission Electron Microscopy (TEM) observation in the high resolution mode (HREM) as well as planar view TEM observations and selected area electron diffraction experiments were performed on very thin carbonised layers. They show that a transition from positive to negative strain values occurred when T_(intro) reached 1050℃. This is related with a change in the SiC microstructure. Below 1150℃, the grain structure could barely be resolved by HREM and the continuous 3C-SiC layer was under a planar tensile strain. Near the transition, tensed and compressed regions co-existed in the nm-thick carbonization layer while for higher T_(intro), relatively large SiC grains (10-30nm) were under a strong compressive strain. This seems to indicate that two different mechanisms are involved in the Si carbonization process leading to distinct SiC strain and microstructure characteristics.