FORMATION OF BURIED EPITAXIAL SILICON-CARBIDE LAYERS IN SILICON BY ION-BEAM SYNTHESIS

RBS/channeling, X-ray diffraction and transmission electron microscopy (TEM) as well as cross-sectional transmission electron microscopy (XT EM) are used to study the formation of well-defined, epitaxial 3C-SiC layers in Si(100) and Si(111) by high dose implantation of 180 keV C i ons and subsequent thermal annealing at 1250 degrees C. The dose depen dence of the carbon redistribution during the post-implantation anneal is studied in detail, revealing the possibility to grow well-defined substoichiometric and stoichiometric silicon carbide layers as well as 3C-SiC layers with a large concentration of excess carbon atoms. The presence of crystalline SiC nuclei in the as implanted state and their depth distribution are shown to be important for the carbon redistrib ution into a discrete layer during annealing. XRD monitoring of the ep itaxial 3C-SiC component formed during implantation indicates the buil d-up of lattice distortions close to the stoichiometry dose. After ann ealing, the approximately 170 nm thick continuous SiC layers are cover ed by 300 nm thick crystalline silicon top layers, containing individu al SiC precipitates. Cross-sectional TEM investigations reveal sharp i nterfaces between Si and SiC layers and almost unstrained Si on top an d underneath the layers. First results are reported indicating that Si C can be formed also in homogenous deep buried layers using MeV ion be am synthesis.