Optical, structural and electrical properties of device-quality hydrogenated amorphous silicon-nitrogen films deposited by plasma-enhanced chemical vapour deposition

High-electronic quality hydrogenated amorphous silicon-nitrogen (a- Si1- xNx : H) ® lms with an energy gap in the range 1.9± 2.7 eV have been deposited by plasma-enhanced chemical vapour deposition in silane± ammonia gas mixtures at two di€ erent gas residence times and in hydrogen-diluted silane± ammonia gas mixtures. Compositional, structural, electrical and optical properties have been investigated. For the ® rst time the e€ ects of hydrogen dilution of SiH4+ NH3 gas mixtures on the a-Si1- xNx : H network is reported. We have observed that hydrogen dilution decreases hydrogen incorporation and increases nitrogen incorporation, promoting a higher connectivity of the a-Si1- xNx :H network. All ® lms show good electronic properties, comparable with or superior to those of amorphous silicon± carbon ® lms, which are improved in ® lms deposited from hydrogen-diluted gas mixtures.