US Patent 7595509 Single crystal wafer for semiconductor laser

A surface of the single crystal wafer 5 for semiconductor laser having an orientation flat formed by cleaving is polished by using the abrasive cloth 8 with high hardness under the optimized pressure for pushing the wafer and polishing rate, such that the polishing rate on the whole surface of the respective wafer 5 becomes uniform. The facet roll-off D occurred at a ridge of a cleavage surface 4 of the single crystal wafer 5 for semiconductor laser to be equal to or less than 40 μm. The single crystal wafer for a semiconductor laser of the present invention can provide an improvement in a precision of an optical alignment of mask pattern using the cleavage surface as a reference, and an improvement in process yield.