a thin film transistor and a method of manufacturing the same such that an ohmic contact can be formed between a semiconductor layer and a source electrode or between the semiconductor layer and a drain electrode , wherein the tft can be applied to a plastic substrate . the tft includes : a substrate ; an active layer formed of zno , inzno , znsno , and / or zningao on the substrate and including a channel region , a source region , and a drain region ; a gate electrode insulated from the active layer ; and source and drain electrodes insulated from the gate electrode and electrically connected to the source region and the drain region , respectively , wherein the source region and the drain region of the active layer include hydrogen .