Abstract: In a rectangular, square or other shaped single-crystal wafer of a III-V group compound semiconductor, one corner of the wafer is cut off, provided with a marking, or the wafer has a part of the original shape of the grown single-crystal ingot left intact on one side of the wafer. With the wafers thus formed, it can be distinguished between the front and back sides of the wafer, or also the direction in which a V groove etch is to occur can be identified.

Abstract: Identification of the front surface and whether the front surface has a mesa direction for wafers of compound semiconductors belonging to group III-V have a crystalline structure of the zinc blende type. The wafer has asymmetric peripheral edge with regard to a middle plane to denote the front surface. Another asymmetry as well as the edge asymmetry determines the front surface and the mesa direction on the surface. The other asymmetry is an orientation flat in a circular wafer. The asymmetry of the peripheral edge is given by the half round whose curvature changes in the direction of the thickness, two slanting parts whose lengths are different or a slanting part or a perpendicular part which are formed in succession in the direction of the thickness on the peripheral edge and so on.