Transistors, methods of manufacturing a transistor, and electronic devices including a transistor are provided, the transistor includes a channel layer, a source and a drain respectively contacting opposing ends of the channel layer, a gate corresponding to the channel layer, a gate insulating layer between the channel layer and the gate, and a first passivation layer and a second passivation layer sequentially disposed on the gate insulating layer. The first passivation layer covers the source, the drain, the gate, the gate insulating layer and the channel layer. The second passivation layer includes fluorine (F).