A two-dimensional semiconductor device and an electrode used therein are provided. The material of the contact electrode is a semi-metal alloy, and the semi-metal alloy is composed of several semi-metal elements or at least one semi-metal element and an alloy material thereof. The two-dimensional semiconductor device includes a substrate, a two-dimensional semiconductor material layer formed on the substrate, and electrodes formed on the two-dimensional semiconductor material layer. The electrodes include the contact electrode and the metal electrode, and the contact electrode is between the metal electrode and the two-dimensional semiconductor material layer, so that the semi-metal alloy forms a space gap slightly smaller than a Van der Waals distance on top of the two-dimensional semiconductor to ensure the stability of the structure while preventing/minimizing the coupling of outer orbital electrons between the two-dimensional semiconductor and the electrode. |