The deposition parameters of doped hydrogenated nanocrystalline silicon grown by plasma-enhanced chemical vapor deposition were scanned to obtain highly conductive films. The optimized p(+) and n(+) nc-Si: H films were used as injecting layers in the fabrication of Si-rich hydrogenated amorphous silicon nitride (a-SiN(x) : H)-based heterojunction p(+) in(+) diode. The as-grown diode was subjected to a Joule-heating-assisted forming process (FP) via the application of a high electric field. The modifications in the luminescent, electrical, and structural properties of the diode subsequent to the FP were investigated. Although the energy distribution of electroluminescence remains almost the same when compared with that of the fresh diode, its intensity is enhanced by at least 30 times with an orange-red emission easily perceived by the naked eye. Parallelly, the low field-current density drastically increases, presumably due to the Si-nanocrystallite formation within the a-SiN(x) : H layer. This formation, triggered by the neighboring nanocrystalline-doped layers, was confirmed by the X-ray diffraction measurements indicating the rise in the local temperature during FP.