Titanium silicide thin films which can apply to infrared-ray sensor were manufactured by a-Si:H/Ti/Si(100) thin film (A process), Ti/a-Si:H/Si(100) thin film (B process), fabricated by dilute gas (H2) Ti/a-Si:H/Si(100) thin film (C process) with annealing processes. In the particularly, we studied the applicable capability for near infrared-ray sensor and ascertained the effect of grain size and morphology to band-gap and the number of defect. From the correlation between band-gap and the number of defect, we will be interpreted the process condition that showed specific band-gap.