Abstract
The electrical resistivity of 4H-SiC doped with nitrogen is analyzed in the temperature range 10-700 K for nitrogen concentrations between 3.5x10(15) and 5x10(19) cm(-3). For the highest doped samples, a good agreement is found between the experimental resistivity and the values calculated from a generalized Drude approach at similar dopant concentration and temperature. From these results, the critical concentration (N-c) of nitrogen impurities which corresponds to the metal-nonmetal transition in 4H-SiC is deduced. We find N-c similar to 10(19) cm(-3).