The plasma parameters in 915 MHz ECR plasma with SiH4/H-2 mixtures were investigated using a heated Langmuir probe where extremely high dilution ratio of H-2 to SiH4 was used for preparing microcrystalline silicon thin films. As the incident microwave power was increased, the electron temperature (T-e) decreased from 7 eV to 2-3 eV and the electron density (n(e)) increased from 0.5 x 10(11) cm(-3) to 1.3 x 10(11) cm(-3), that is, low T-e ECR plasma with high n, was realized using 915 MHz microwaves. As a result of the film deposition, it was found that there is a correlation between the T-e and crystallinity of the microcrystalline silicon. Furthermore, it was shown that high deposition rate can be realized by increasing the gas flow rate. (c) 2007 Elsevier B.V. All rights reserved.