Optically detected electron paramagnetic resonance of AlN single crystals

AlN single crystals have been investigated using photoluminescence (PL) and optical detection of electron paramagnetic resonance in the PL (ODEPR). Al l crystals were found to exhibit intense PL extending from the visible into the near infrared. Several S=1 centers, each with its own distinct emissio n spectrum, and distant S=1/2 pair recombination centers have been observed via ODEPR. In all except one center, D5, no hyperfine structure was observ ed preventing chemical identification of the impurity involved. In the case of D5 the partially resolved hyperfine structure suggests interaction with a 100% abundant nucleus of I similar to 5/2. We present arguments to assoc iate it with a displaced host aluminum atom. [S0163-1829(99)03004-0].