The invention discloses a switching devise for a pixel electrode of display devise and methods for fabricating the same. A gate is formed on a portion of a substrate. A semiconductor layer is formed on the gate. A source and a drain are formed on a portion of the semiconductor layer. A low-k (low dielectric constant) materia layer, such as a layer of a-SiC:H or a-SiCN:H, is formed between the gate and the semiconductor layer and/or on the source/ drain.