Near-surface lateral vacancy migration in O+-implanted SiC studied by positron re-emission microscopy

The areal distribution of near-surface defects created by the implantation of O+ ions into 6H–SiC through chemically-deposited masks has been studied by reflection-geometry positron re-emission microscopy (PRM). PRM images were obtained for ion doses of 1×1013 and 1×1014 cm−2. The ratios of re-emitted positron intensities from unmasked and masked regions of the two samples were measured to be 78(3)% and 45(3)%, respectively. These results are consistent with the trapping of thermalised positrons prior to reaching the exit surface; the sharpness of images obtained from the low fluence sample is also consistent with work-function, rather than epithermal, emission from the sample. Removal of the instrumental resolution function from the image from the higher fluence sample shows evidence of lateral subsurface vacancy migration characterised by a broadening function of 44(5) μm F.W.H.M.