For effectively reducing the off-state signal loss resulted from the a-Si:H TFTs photo leakage current, the a-Si:H TFTs with the use of ITO as source-drain metal have been fabricated for this study. Several TFT structures have been fabricated to examine this characteristic. A remarkable reduction in photo leakage current has been observed under the 3300 cd/m(2) CCFL backlight illumination. The source-drain barrier height engineering has been proposed for these results. According to the energy band diagram, the barrier height for hole is estimated about 3 eV. As a result, the photo-generation holes blocked in the source-drain barrier height could effectively reduce the photo leakage current in off-state. (C) 2007 Elsevier B.V. All rights reserved.