▎ 摘　　要

NOVELTY - The transistor has a semiconductor channel region formed above the substrate layer. A first electrode and second electrode are formed in the semiconductor channel region. A preset distance interval is between first electrode and second electrode. A gate dielectric layer is formed on at least a part of the upper surface of the semiconductor channel region. The substrate layer is formed with a concave part. The concave part has a bottom surface. The lower surface of semiconductor channel region and bottom surface of concave part have a preset distance, or the part of semiconductor channel region and bottom surface of concave part are contact. The materials for forming semiconductor channel region comprise semiconductor metal oxides, two-dimensional transition metal sulfides, graphene, carbon nano-tube, carbon nano-wire, semiconductor nano-wire, organic semiconductors, black phosphorus or molybdenum disulfide. USE - Used as transistor. ADVANTAGE - The transistor: prevents the recess from being formed on lower end of gate dielectric layer so as to prevent short-circuit between recess and gate electrode, diffusion of impurities e.g. impurities from the substrate layer into channel regions of transistor, and the transistor from being damaged by the impurities; and improves reliability and performance of transistors. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a preparation method of transistor. DESCRIPTION OF DRAWING(S) - The drawing shows a structure schematic diagram of the transistor.