Abstract: A semiconductor device includes a substrate, an initial layer, and a superlattice stack. The initial layer is located on the substrate and includes aluminum nitride (AlN). The superlattice stack is located on the initial layer and includes a plurality of first films, a plurality of second films and at least one doped layer, and the first films and the second films are alternately stacked on the initial layer, wherein the at least one doped layer is arranged in one of the first films and the second films, and dopants of the at least one doped layer are selected from a group consisting of carbon, iron, and the combination thereof.

Abstract: A semiconductor device includes a substrate, an initial layer, and a superlattice stack. The initial layer is located on the substrate and includes aluminum nitride (AlN). The superlattice stack is located on the initial layer and includes a plurality of first films, a plurality of second films and at least one doped layer, and the first films and the second films are alternately stacked on the initial layer, wherein the at least one doped layer is arranged in one of the first films and the second films, and dopants of the at least one doped layer are selected from a group consisting of carbon, iron, and the combination thereof.

Abstract: A semiconductor device includes a substrate, an initial layer, and a superlattice stack. The initial layer is located on the substrate and includes aluminum nitride (AlN). The superlattice stack is located on the initial layer and includes a plurality of first films and a plurality of second films, and the first films and the second films are alternately stacked on the initial layer. If the first films are doped films having dopants selected from a group consisting of carbon, iron, and the combination thereof, the second films do not include dopants substantially; if the second films are doped films having dopants selected from a group consisting of carbon, iron, and the combination thereof, the first films do not include dopants substantially.

Abstract: A semiconductor device includes a substrate, an initial layer, and a buffer stack structure. The initial layer is located on the substrate and includes aluminum nitride (AlN). The buffer stack structure is located on the initial layer and includes a plurality of base layers and at least one doped layer positioned between two adjacent base layers. Each of the base layers includes aluminum gallium nitride (AlGaN), and the doped layer includes AlGaN or boron aluminum gallium nitride (BAlGaN). In the buffer stack structure, concentrations of aluminum in the base layers gradually decrease, concentrations of gallium in the base layers gradually increase, the base layers do not contain carbon substantially, and dopants in the doped layer include carbon or iron.

Abstract: A nanosheet includes a 2H—SiC layer having a first surface and a second surface, the first and second surfaces being opposed to each other; a first graphene layer formed of 1-10 graphenes being disposed on the first surface; and a second graphene layer formed of 1-10 graphenes being disposed on the second surface.