The effect of the hydrogen dilution ratio on characteristics of hydrogenated boron-doped nanocrystalline silicon-silicon carbide alloy (p-nc-Si-SiC:H) films is investigated. Hydrogen coverage near the growing surface causes nanocrystallization by retarding the reactions of the precursors. It was found that p-nc-Si-SiC:H alloys have two different kinds of carrier transport mechanisms: one is the thermally activated hopping conduction between neighboring crystallites near room temperature and the other is the band tail hopping conduction below 150 K. However, the film at the onset of the nanocrystalline growth exhibits a different behavior due to a large band tail disorder. (c) 2006 American Institute of Physics.