Specific features of electron spin resonance in 4H-SiC in the vicinity of the insulator-metal phase transition: II. Analysis of the width and shape of lines

The variation in the width and shape of the ESR line of nitrogen in 4H-SiC in the concentration range corresponding to the insulator-metal phase transition was investigated. It is shown that the spin relaxation in the region of hopping and metal conduction occurs at electrical multipoles (clusters) whose sizes decrease from rather large to small (characteristic of interimpurity distances) as the concentration of impurity centers increases. Analysis of the temperature dependences of the resistance made it possible to estimate the critical concentration for the insulator-metal phase transition (N _D -N _A )_c≈1.5×10¹⁹ cm^?3. The values of other characteristic concentrations that determine the effects of electron-electron interaction in the system under study were also found.