We report on growth of nanocrystalline Si:H films and devices using a layer-by-layer growth technique, where the growth of a thin amorphous layer by PECVD is followed by chemical annealing in a Helium plasma. The films and devices were grown using a remote, low pressure ECR plasma process. It was found that the structure of the films grown using the layerby-layer technique depended critically upon whether the annealing was done with hydrogen or helium, and the time taken to do the annealing. When the annealing was done in a hydrogen plasma, the films remained amorphous; in contrast, when the annealing was done in helium, and the annealing time was increased to 20 seconds from 10 seconds, the films became crystalline. The crystallinity of the films was confirmed using Raman spectroscopy and x-ray diffraction. The result obtained here shows that it is not necessary to have a high hydrogen dilution to obtain nanocrystalline films. Rather, the amount of hydrogen already present in an amorphous film is enough to cause crystallization, provided that enough ion flux and perhaps energy are available for converting the amorphous structure to a crystalline structure. Proof - of - concept p+nn+ junction devices were fabricated in these chemically annealed materials, and they showed classical nanocrystalline Si solar cell type behavior.