Hydrogenated nanocrystalline silicon (nc-Si:H) thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) at a RF power of 100 W; SiH(4) and H(2) were introduced into a reaction chamber at 25 and 40 sccm, respectively, and the substrate temperature ranged from room temperature to 600 degrees C. The effect of the substrate temperature on the formation of nanoscale Si crystallites (nc-Si) and their structural and optical features were investigated. The average size and concentration of the Si nanocrystallites varied with the substrate temperature; the former ranged from similar to 1.0 to similar to 5.0 nm, and the latter reached up to similar to 15.5% when the substrate temperature was 400 degrees C. With increasing substrate temperature to 400 degrees C, the relative fraction of Si-H bonds in the films, [Si-H]/Sigma(3)(n-1) [Si-H(n)](n-integer), was increased up to similar to 29.3%. (C) 2009 Elsevier B. V. All rights reserved.