In this study, a low-k material, siloxane-based hydrogen silsesquioxane (HSQ) has been investigated for a passivation dielectric between the transistor and pixel levels in thin-film transistor (TFT) arrays. The characteristics of low-k dielectric film have been studied, especially under visible light illumination and electric operation. Compared with the conventional nitride film (k similar to 7), the HSQ passivation layer (k similar to 2.8) not only lowers the RC time delay in device, but also enhances the brightness of thin-film transistors liquid crystal displays (TFT-LCDs). (c) 2005 Published by Elsevier B.V.