Increased medium-range order in amorphous silicon with increased substratetemperature

Using fluctuation electron microscopy, we have measured the medium-range or der of magnetron sputtered silicon thin films as a function of substrate te mperature from the amorphous to polycrystalline regimes. We find a smooth i ncrease in the medium-range order of the samples, which we interpret in the context of the paracrystalline structural model as an increase in the size of and/or volume fraction occupied by the paracrystalline grains. These da ta are counter to the long-standing belief that there is a sharp transition between amorphous and polycrystalline structures as a function of substrat e temperature. (C) 2001 Elsevier Science B.V. All rights reserved.