Abstract: Hydrogenated nano -crystalline silicon (nc-Si: AH) films have been prepared by plasma enhanced chemical vapor deposition (PECVD) method under excellently controlled conditions of deposition. The nc-Si: H Films consist of a mass of nanometer scale grains and an interfacial region, i.e. the crystalline phase and the grain boundaries phase. It is especially valuable for some devices for example, quantum function devices and film sensors etc.