EPR-SPECTRUM OF DONORS IN 6H-SIC IN A BROAD TEMPERATURE-RANGE

An EPR study of donors in 6H SiC crystals with an uncompensated donor concentration (N-D-N-A) of 2 x 10(18) to 1 x 10(16) cm(-3) performed i n the temperature range 4.2 to 160 K at frequencies of 9 and 140 GHz s howed that 6H n-SiC samples have two donor states in the gap. One of t hem originates from nitrogen occupying three inequivalent lattice site s with ionization energies of 150 and 80 meV, and the second is connec ted with a structural defect lying deeper in the gap than nitrogen. Th e temperature dependences of donor EPR line intensities have been foun d to deviate from the Curie law. The observed EPR line-intensity peaks of donors are produced in a temperature-driven successive redistribut ion of donor electrons between the donor levels. The temperature depen dences of EPR line intensities obtained from samples with low donor co ncentrations were used to determine the valley-orbit splitting of nitr ogen in cubic sites. (C) 1998 American Institute of Physics. [S1063-78 34(98)01110-1].