Measurements of current‐voltage characteristics have been performed on Au‐Si3N4‐Mo and Au‐Si3N4‐Si (degenerate substrate) structures of various nitride‐film thicknesses from 300 Å to 3000 Å and over a range of temperatures. The films are deposited by the process of reaction of SiCl4with NH3. It is found that at any given temperature and electric field, the current transport is essentially independent of the substrate material, the film thickness, or the polarity of the electrodes.It is proposed that the current‐transport mechanisms are bulk controlled rather than electrode controlled. The conduction‐current density,J, is the sum of three contributions:J=J1+J2+J3, whereJ1∼Eexp {−q[&phgr;1− (qE/&pgr;&egr;0&egr;d)½]/kT},J2∼E2exp (−E2/E), andJ3∼Eexp (−q&phgr;3/kT). At high fields and high temperaturesJ1dominates the current conduction (the Poole‐Frenkel effect or internal Schottky effect); one obtains a barrier height of (1.3±0.2) V for &phgr;1and a value of 5.5±1 for the dynamic dielectric constant &egr;d. At high fields and low temperaturesJ2dominates as a result of field ionization of trapped electrons (presumably from the same centers as forJ1) into the conduction band; one obtains a value for the fieldE2of the order of 6×107V/cm. At low fields and moderate temperaturesJ3dominates because of the hopping of thermally excited electrons from one isolated state to another yielding Ohmic characteristics and a thermal‐activation energyq&phgr;3of about 0.1 eV.At low temperatures the maximum dielectric strength approached ∼107V/cm. At high temperatures whereJ1dominates the current conduction, the maximum dielectric strength, which is limited by thermal instability, decreases as (&phgr;1−CT)2, whereCis a function of the thermal conductivity of the nitride films.