Impurities and Structural Defects in SiC Determined by ESR

ESR has been used to characterize a number of impurity-related and structural defects in several polytypes of SiC. Most centres observed in SiC can be described by a simple spin-Hamiltonian  

Nitrogen, which is a residual shallow donor in all polytypes, is the most extensively studied impurity in both Lely grown crystals and CVD grown films. Other impurities which have been investigated include acceptors and transition metals. Radiation-induced structural defects have been studied in 3C and 6H polytypes, initially in Lely grown crystals and more recently in CVD grown films. 

Clearly, the most important impurity in all polytypes of SiC is nitrogen, which appears to primarily substitute for carbon and act as a shallow donor. There is some dispute over 

Altaiskii et al [1] were the first to report on the ESR spectrum of nitrogen donors in Lely grown 3C single crystals. In that study the three-line spectrum is partially resolved. Later work by Carlos et al [2] showed that a well resolved three-line spectrum could be obtained for the CVD films as shown in FIGURE 1. The g-tensor and hyperfine interaction are isotropic with g = 2.0050 and A = 0.11 mT. Both of these parameters are in good agreement with expectations from simple effective-mass-approximation calculations for this polytype [5]. 

FIGURE 1 The three-line ESR spectrum of the nitrogen donor in 3C-SiC taken at 20 K. The lineshape is 

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Impurities and structural defects in SiC determined by ESR TABLE 1 Parameters of the N-donor. 

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