a‐SiNx:H films of various compositionxwere deposited by rf glow discharge (GD). The deposition rate was analyzed for three ranges of gas flow ratioR= [NH3]/[SiH4] depending on the deposition mechanism. Properties of these films were measured by means of x‐ray photoelectron spectroscopy (XPS), infrared (IR) absorption, optical absorption, and the temperature dependence of electrical conductivity. The compositionxwas determined by XPS. For large values ofR,xwas found to be saturated at 1.7. The variation of H content was detected by IR absorption. The variation of coordinating atoms of Si with increasingxwas deduced from the variation of XPS spectra of the Si 2pcore‐level and the shift of Si‐H stretching vibration frequency in IR absorption. Based on the random bonding model and assuming bonding units to the central Si atom to be Si, N, and NH, probabilities of Si tetrahedra with various coordinating units were obtained. The results indicate that there are many Si—Si bonds for the stoichiometricx=1.33 and that the concentration of Si—Si bonds diminishes at around the saturation valuex=1.7. These results seem to imply that the presence of Si—Si bonds to some extent is a prerequisite condition for film deposition by GD. Experimental results of optical absorption analyzed by Tauc relation revealed the presence of two kinds ofxregion whose properties are quite different.Forx<1.5, its optical absorption is similar toa‐Si:H modified by the presence of N. With increasingx, the optical band gapEOincreases andBcoefficient in the Tauc plot decreases. At aboutx=1.5, Si—Si bonding effectively disappears and the optical absorption abruptly changes to that similar to &bgr;‐Si3N4. Considering these results, the change of electronic band structure withxwas deduced on the basis of the atomic structure obtained above and by the tight binding approximation. Forx<1.5, the optical band gap is due to Si—Si bonding, the energy gap of which increases, and the linear band tail becomes broad with increasingx. From the observed temperature dependence of conductivity, variations of the activation energy and pre‐exponential factor are obtained withxup tox=1.0. For the decrease of conductivity withx, the contribution from the pre‐exponential factor is much larger than that from the activation energy. This result can be understood by a transport mechanism in the electronic band structure obtained above. Finally, it is concluded that the electronic properties ofa‐SiNx:H deposited by GD ran.