A method of forming a group III-V material layer, a semiconductor device including the group III-V material layer, and a method of manufacturing the semiconductor device. The device comprises a seating element which can be pivoted transversally to the seating direction in relation to a support element about at least one axis. When the sheets are stacked, a swing regulating portion 12 regulates the swing of the auxiliary tray 1 when the tray 2 is in a sheet stacking position and releases the regulation of the swing of the auxiliary tray 1 when the tray 2 is lifted. The instructing unit provides an instruction for a shutoff of electricity generation.