Photonic integrated circuit having improved electrical isolation between n-type contacts

A photonic integrated circuit, comprising:

• a semiconductor wafer that has an epitaxial layer stack comprising:
• an n-type doped contact layer comprising indium phosphide or a non-intentionally doped layer comprising indium phosphide, said non-intentionally doped layer comprising at least two selectively n-type doped contact regions, wherein said n-type doped contact layer or said non-intentionally doped layer outside said at least two selectively n-type doped contact regions comprises a first selectively p-type doped tubular-shaped region that is configured and arranged to provide a first electrical barrier between:
• a first area of said n-type doped contact layer that is surrounded by said first selectively p-type doped tubular-shaped region and a second area of said n-type doped contact layer that is arranged outside said first selectively p-type doped tubular-shaped region;
• or
• a first selectively n-type doped contact region of said non-intentionally doped layer that is surrounded by said first selectively p-type doped tubular-shaped region and a second selectively n-type doped contact region of said non-intentionally doped layer that is arranged outside said first selectively p-type doped tubular-shaped region;
• and
• a non-intentionally doped waveguide layer comprising indium gallium arsenide phosphide that is arranged on top of said n-type doped contact layer or said non-intentionally doped layer;
• a first opto-electronic device that is arranged in said first area of said n-type doped contact layer that is surrounded by said first selectively p-type doped tubular-shaped region or in said first selectively n-type doped contact region of said non-intentionally doped layer that is surrounded by said first selectively p-type doped tubular-shaped region, said first opto-electronic device comprising a first n-type ohmic metal contact that is arranged at a first location on said n-type doped contact layer within said first area or at a first location on said first selectively n-type doped contact region;
• a second opto-electronic device that is arranged in said second area of said n-type doped contact layer that is arranged outside said first selectively p-type doped tubular-shaped region or in said second selectively n-type doped contact region of said non-intentionally doped layer that is arranged outside said first selectively p-type doped tubular-shaped region, said second opto-electronic device comprising a second n-type ohmic metal contact that is arranged at a second location on said n-type doped contact layer within said second area or at a second location on said second selectively n-type doped contact region;
• and
• a passive optical waveguide comprising said non-intentionally doped waveguide layer and being arranged to optically interconnect said first opto-electronic device and said second opto-electronic device, wherein a first portion of said first selectively p-type doped tubular-shaped region is arranged underneath said passive optical waveguide between said first opto-electronic device and said second opto-electronic device.