▎ 摘　　要

NOVELTY - The structure has a first substrate layer (1) and a second substrate layer (2). The p-type gallium nitride-based material is doped with magnesium elements and grown on the first base layer. A graphene layer (3) is placed on the second base layer. A third substrate layer (4) is provided with an n-type gold nitride base material growing on the graphene layer, where the second and third base materials form a pn junction. The graphene layer blocks the magnesium elements from diffusing to the third base layer and is suitable for blocking the molybdenum element of the second substrate to diffuse. USE - Semiconductor pn structure e.g. trench-type MOSFET for semiconductor device (claimed), used in microelectronics and optoelectronic applications. ADVANTAGE - The forward conduction and reverse cut-off characteristics of the semiconductor pn structure is improved. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) a preparation method of semiconductor pn structure; and (2) a semiconductor device. DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram illustrating the semiconductor pn structure. (Drawing includes non-English language text) 1First substrate layer 2Second substrate layer 3Graphene layer 4Third substrate layer