Excited defect energy states from temperature dependent ESR.

We report on the determination of valley-orbit splittings of nitrogen in different SiC polytypes by exploiting the temperature dependence of the ESR signal amplitudes. The effect is shown to be caused by an Orbach spin-lattice relaxation process and, therefore, enables us to measure relaxation times. The reliability of the method was tested by detection of the is ground state splitting of phosphorus and arsenic in silicon and it is applied to other defects in Si:P as -well as to the GaAs antisite related defect in GaAs. New results on hyperfine splittings are presented, too.