Evolution of ion implantation-caused vacancy-type defects in 6H–SiC probed by slow positron implantation spectroscopy

6H–SiC n-type wafers were implanted with Al+ and N+ ions in two steps: first Al+ double implantation (100 keV, 5×1016 cm−2 and 160 keV, 1.3×1017 cm−2) followed by N+ double implantation (65 keV, 5×1016 cm−2, 120 keV, 1.3×1017 cm−2). The implantation was carried out at a substrate temperature of 800 °C in order to avoid amorphisation. In this way a buried SiC1−x(AlN)x layer could be created. Variable-energy positron Doppler broadening measurements were performed at room temperature using a magnetic transport beam system in order to characterise the vacancy-type defects created by ion implantation. Depth profiles could be evaluated from the measured Doppler broadening profiles. The defect distribution and the defect size after the complete co-implantation are discussed and the contribution of the different implantation steps to the evolution of this defect structure is shown.