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 we re obtained for ion doses of 1x10(13) and 1 x 10(14) 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 reachin g the exit surface; the sharpness of images obtained from the low fluence s ample is also consistent with work-function, rather than epithermal, emissi on from the sample. Removal of the instrumental resolution function from th e image from the higher fluence sample shows evidence of lateral subsurface vacancy migration characterised by a broadening function of 44(5) mu m F.W .H.M. (C) 1999 Elsevier Science B.V. All rights reserved.