US Patent 11837676 Optical semiconductor device and optical transmission apparatus

An apparatus includes a first semiconductor layer including a first bandgap; and a second semiconductor layer of a first polarity including a second bandgap smaller than the first bandgap and formed over the first semiconductor layer. The first semiconductor layer includes a first conductive region of the first polarity, a second conductive region of a second polarity, and a non-conductive region between the first conductive region and the second conductive region, and the second semiconductor layer is in contact with the first conductive region and the non-conductive region.