Provided is a method for fabricating a filed effect transistor, the method comprising: depositing a first semiconductor layer and a second semiconductor layer on a substrate in sequence, which have a different bandgap from each other, and patterning the second semiconductor layer to have a mesa structure; forming a first resist pattern to expose the second semiconductor layer of a region where source and drain are to be formed; depositing a metal on a whole upper surface, and forming metallic source and drain by performing a lift-off process; performing heat treatment to form an ohmic contact between the source and the second semiconductor layer, and between the drain and the semiconductor layer; forming an insulating layer on the whole upper surface including the source and the drain, and forming a second photoresist pattern to expose the insulating layer at a portion where a gate is to be formed; exposing the second semiconductor layer at the portion where the gate is to be formed by etching the exposed portion of the insulating layer; and depositing the metal on the whole upper surface in a state that the temperature of the substrate is lowered to perform low temperature vacuum deposition, and forming a metallic gate by performing a lift-off process and an insulating layer removing process.