Vacancy-type defects in 6H-SiC caused by N+ and Al+ high fluence co-implantation

6H-SiC n-type wafers were implanted with Al+ and N+ ions in two steps: first N+ double implantation (65 keV, 5x1016 cm-2 , 120 keV, 1.3x1017 cm-2 ) followed by Al+ double implantation (100 keV, 5x1016 cm-2 and 160 keV, 1.3x1017 cm-2 ). The implantation was carried out at a substrate temperature of 800 0C 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 characterize 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.