Microstructural features of Al-implanted 4H–SiC

The microstructural features of highly damaged 4H–SiC implanted with Al₂²⁺ ions at 450 K were studied using transmission electron microscopy (TEM) and electron energy-loss spectroscopy. Conventional TEM images reveal that the crystalline SiC domains are highly strained/distorted when the relative disorder on the Si sublattice ranges between about 0.4 and 0.8, as determined by Rutherford backscattering spectrometry in channeling geometry. As the relative disorder approaches 1.0, the high strain contrast appears to be relieved, and localized amorphized domains are observed. Plasmon-loss energy shows a red shift following the implantation, and the magnitude of the red shift increases with increasing relative disorder. Based on the red shift, the estimated volume expansion is approximately 8% for highly damaged crystalline SiC and approximately 16% for the amorphous state. Energy-loss near-edge-structure of both the C and Si K edge reveals the existence of Si–Si and C–C bonding in the Al₂²⁺ implanted SiC.