ODMR Investigations of Defects and Recombination Processes in SiC

Optically-Detected Magnetic Resonance (ODMR) has provided magnetic and hyperfine parameters for excited states of defects in SiC. Since ODMR combines EPR with photoluminescence, it gives a link between the information provided by each experiment. In SiC, most of the publications describe donor- and acceptor-resonances detected on distant donor-acceptor-pair (DAP) recombination. As in the other experiments, interesting effects occur due to the different symmetries which arise from the polytypism of SiC. 

ODMR depends on the existence of spin selection rules for the recombination of an electron and hole. Since most of the published results in SiC concern DAP recombination, the data can be understood with the spin Hamiltonian for a weakly coupled donor-acceptor pair  

The ODMR results have been placed into three groups. First, the results on donors and acceptors are reviewed. Second, the ODMR of Ti in SiC is described. Finally, the work on native and radiation-induced defects is presented. 

This trend reflects the exchange interaction between the electron and hole. For given concentrations of donors and acceptors, there is a distribution in the separations between pairs. Slow microwave-modulation frequencies can emphasize the importance of the sharper, more distant pairs (see FIGURE 2). So far, the best donor linewidth of about 1 mT has precluded the observation of N-hyperfine splitting in the 3C polytype, which EPR has shown to be 0.12mT. 

Polytype Quench ing/Enhancing Emission band g-tensor (error) l4N Hyperfine Ref 

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ODMR investigations of defects and recombination processes in SiC C ACCEPTORS... 

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