Percolation-controlled electronic properties in microcrystalline silicon: effective medium approach

Electronic transport and optical properties of microcrystalline Si prepared by plasma enhanced chemical vapor deposition are discussed in terms of effective medium approximation (EMA). The electrical conductivity and the Hall mobility as a function of volume fraction of crystalline are replicated well by the EMA calculation with a percolation threshold at 33% crystalline volume fraction. The well known excess optical absorption in fundamental absorption region can be also explained by the EMA. The Hall mobility is sublinearly proportional to the size of crystallites when the volume fraction of crystallite is kept the same, which is attributed to a fractal property of microcrystalline system. (C) 2000 Elsevier Science B.V. All rights reserved.