a-Si : H TFTs for image sensor have been fabricated and their operational characteristics have been investigated. Hydrogenated amorphous silicon nitride(a-SiN : H) films were used for the gate insulator and n^+-a-Si : H films were depostied for the source and drain contact. The thicknesses of a-SiN : H and a-Si : H films were 2000 Å, respectively and the thickness of n+-a-Si : H film was 500 Å. Also the channel length and channel width of a-Si : H TFTs were 50 ㎛ and 1000 ㎛ respectively. The ON/OFF current ratio, threshold voltage. and field effect mobility of fabricated a-Si : H TFTs were 10^5, 6.3 V, and 0.15 ㎠/V·s, respectively.