The hysteresis observed in capacitance‐voltage (C‐V) measurements on metal‐sputtered silicon nitride—silicon structures indicates that carriers are injected predominantly as holes rather than electrons. Shifts in the C‐V characteristic after bias‐temperature stress at 300°C support this finding. In dc conduction measurements on these samples a linear relation was found between the logarithm of current and the square root of field. The slope of this plot and the independence of current on bias polarity indicate a bulk‐limited conduction mechanism of emission of carriers from traps in the silicon nitride.