Electric breakdown in GaNp‐njunctions was investigated. GaNp+‐p‐n+structures were grown on 6H–SiC substrates by metalorganic chemical vapor deposition. Mg and Si were used as dopants. Mesa structures were fabricated by reactive ion etching. Capacitance–voltage measurements showed that thep‐njunctions were linearly graded. The impurity gradient in thep‐njunctions ranged from 2×1022to 2×1023cm−4. Reverse current–voltage characteristics of thep‐njunctions were studied in the temperature range from 200 to 600 K. The diodes exhibited abrupt breakdown at a reverse voltage of 40–150 V. The breakdown had a microplasmic nature. The strength of the electric breakdown field in thep‐njunctions depended on the impurity gradient and was measured to be from 1.5 to 3 MV/cm. It was found that the breakdown voltage increases with temperature. The temperature coefficient of the breakdown voltage was ∼2×10−2V/K. ©1996 American Institute of Physics.