The effects of power density and chamber pressure on the nanocrystalline silicon thin films have been studied in high-pressure-high-power regime by plasma-enhanced chemical vapour deposition process at a plasma excitation frequency of 54.24 MHz. For all the films prepared at high hydrogen dilution, grain sizes lie in the range 6-14.4 nm. Maximum crystalline volume fraction of 84.9% is obtained for films deposited at a power density of 0.7 W/cm(2). Crystallinity decreases with increase in chamber pressure. Long grains are observed using the high-resolution transmission electron micrograph when films are deposited at high power density. High diffusion length of 610 nm is obtained for films deposited in the transition region of amorphous to nanocrystalline phase. (c) 2007 Elsevier B.V. All rights reserved.