Observation of an interstitial manganese impurity in 6H-SiC
In a 6H-SiC single crystal the authors observed the electron paramagnetic resonance (EPR) of a Mn impurity, which is assigned to an interstitial Mn2+ (3d5) centre with electron spin S=5/2. The assignment of Mn2+ to be on an interstitial site is based on the large hyperfine interaction of 270 MHz. Only the central hyperfine sextet is observed with forbidden transitions in between. The fine structure lines are broadened beyond detection by random internal strains; however, the fine structure interaction causes the forbidden lines. The presence of internal strains is confirmed by the observation of the corresponding EPR spectra of the N donors.