Carbon redistribution in nanometric Si_1-xC_x layers upon ion beam synthesis of SiC by C implantation into SIMOX(111)

Nanometric 3C SiC layers (∼40nm) between amorphous zones, i.e. SiO ₂/SiC/SiO₂/Si, have been obtained using separation by implantation of oxygen (SIMOX) structures on bulk Si(1 1 1) as the starting material, i.e. Si(65nm)/SiO₂/Si(1 1 1) structures. We report mechanisms of carbon redistribution in the starting 65 nm silicon overlayer (SOV) upon SiC ion beam synthesis (IBS). Sequential C implantation steps (sample held at 600 °C), with 1250 °C annealing in between, have allowed us to register the evolution of the carbon composition (previously and after annealing) in the SOV under conversion when increasing the implantation fluence. Rutherford backscattering spectrometry (RBS) and transmission electron microscopy (TEM) reveal a two-sublayer structure of about the same thickness for the layer under conversion. The composition evolution of the sublayers (Si _1-xC_x) was monitored by evaluating Si composition changes measured by RBS analysis. High resolution TEM has demonstrated major differences in the structural quality of sublayers. We suggest that the observed structural differences are the main driving force for the observed C migration.