The analysis of free-carrier optical absorption was applied to investigation of electrical properties for doped microcrystalline silicon films formed at 100-180 degreesC by the RF-plasma-enhanced chemical vapor deposition method. The analysis gave in-depth characteristics of the carrier mobility and the carrier density. The electron mobility was 8 cm(2)/Vs (phosphorous doped) and 6 cm(2)/Vs (boron doped) at the surface region and it decreased to similar to 1 cm(2)/Vs at bottom film/substrate interfaces. The carrier mobility and density were much higher than those obtained by Hall effect current measurements. It shows the existence of substantial nonactivated and disordered regions among crystalline grains. (C) 2001 Elsevier Science B.V. All rights reserved.