TFT substrate and display device having the same

A TFT substrate includes a base substrate, a gate wiring formed on the base substrate, a gate insulation layer, an activation layer, an oxidation-blocking layer, a data wiring, a protection layer and a pixel electrode. The gate wiring includes a gate line and a gate electrode. The gate insulation layer is formed on the base substrate to cover the gate wiring. The activation layer is formed on the gate insulation layer. The oxidation-blocking layer is formed on the activation layer. The data wiring includes a data line, a source electrode and a drain electrode. The source and drain electrodes are disposed on the oxidation-blocking layer therefore lowering the on-current ("Ion") for turning on the TFT and increasing the off-current ("Ioff") for turning off the TFT due to the oxidation-blocking layer.