Micro-Raman depth profile investigations of beveled Al+-ion implanted 6H-SiC samples

Abstract

6H-SiC single crystals were implanted with 450keV Al+-ions to a fluence of 3.4×1015cm−2 , and in a separate experiment subjected to multiple Al+ implantations with the four energies: 450, 240, 115 and 50keV and different fluences to obtain rectangular-like depth distributions of Al in SiC. The implantations were performed along [0001] channeling and non-channeling (“random”) directions. Subsequently, the samples were annealed for 10min at 1650°C in an argon atmosphere. The depth profiles of the implanted Al atoms were obtained by secondary ion mass spectrometry (SIMS). Following implantation and annealing, the samples were beveled by mechanical polishing. Confocal micro-Raman spectroscopic investigations were performed with a 532nm wavelength laser beam of a 1μm focus diameter. The technique was used to determine precisely the depth profiles of TO and LO phonon lines intensity in the beveled samples to a depth of about 2000nm. Micro-Raman spectroscopy was also found to be useful in monitoring very low levels of disorder remaining in the Al+ implanted and annealed 6H-SiC samples. The micro-Raman technique combined with sample beveling also made it possible the determination of optical absorption coefficient profiles in implanted subsurface layers.