A structure of semiconductor device including an insulation substrate is provided. A channel layer is disposed on the insulation substrate. A plurality of doped layers is disposed on the insulation substrate, and protrudes from the channel layer. The doped layers form at least two source/drain electrode (S/D electrode) pairs, and each of the S/D electrode pairs has a different extension direction with respect to the channel layer. A gate dielectric layer is disposed on the channel layer. A gate layer is disposed on the gate dielectric layer. Preferably, for example, the extension direction of at least one of the S/D electrode pairs is a first direction, and the extension direction of at least another one of the S/D electrode pairs is a second direction.