Abstract
Hydrogenated amorphous silicon/stoichiometric silicon nitride (a-Si:H/a-Si3N4:H) superlattices have been prepared by the direct photolysis of disilane (Si2H6) and of a silane (SiH4)–ammonia (NH3) gas mixture. It is found that the structure is well defined on an atomic scale and that the optical and electrical properties are well interpreted by quantum-size effects in the ultra-thin a-Si:H layers. In particular, significant enhancement of the luminescence intensity is observed when the a-Si:H well width is less than 50 Å. The extent of the luminescence enhancement is more pronounced for photochemically deposited multilayers than for films obtained by plasma-enhanced chemical vapour deposition CVD. This is attributable to the absence of ion-induced damage in superlattices obtained by photochemical vapour deposition.