The .mu.c-Si:H films have been deposited by PeCVD at the various conditions such as hydrogen dilution ratio, substrate temperature and RF power density. Then, we studied their electrical and optical properties. Top gate hydrogenated micro-crystalline silicon thin film transistors($mu$c-Si:H TFTs) using $mu$-Si:H and a-SiN:H films have been fabricated by FECVD. The electrical characteristics of the devices have been investigated by semiconductor parameter analyzer and compared with amorphous silicon thin film transistors (a-Si:H TFTs). In this study, on/off current ratio, threshold voltage and the field effect mobility of the $mu$c-Si:H TFT were $3{ imes}10^{4}$, 5.06V and 0.94cm$^{2}$Vs, respectively.