An example embodiment relates to a semiconductor device including a semiconductor element. The semiconductor element may include a plurality of unit layers spaced apart from each other in a vertical direction. Each unit layer may include a patterned graphene layer. The patterned graphene layer may be a layer patterned in a nanoscale. The patterned graphene layer may have a nanomesh or nanoribbon structure. The semiconductor device may be a transistor or a diode. An example embodiment relates to a method of making a semiconductor device including a semiconductor element.