Direct measurement of local volume change in ion-irradiated and annealed SiC

Depth profiles of local volume expansions are precisely measured in 6H-SiC after irradiation at 150 K with 2 MeV Pt ions and following annealing at 770 K using transmission electron microscopy equipped with electron energy loss spectroscopy. It is found that the depth profile of local volume expansion from the as-implanted sample matches well with the depth profile of irradiation-induced local disorder measured by Rutherford backscattering spectrometry. Further, the local volume expansion increases linearly with local dose up to ∼10%. By systematically comparing the depth profiles of local volume expansion and local relative disorder, it is revealed that the atomic volume of amorphous SiC continues to increase until it saturates at ∼14% due to the increased chemical short-range disorder. This is believed to be one of the reasons for significant scatter in values of volume expansion previously reported for the irradiation-induced amorphous state of SiC.