The layers down to at least the second type conductivity layer are removed to form a ridge and at least one contact groove, which reaches {HEAD ~ the first type conductivity layer}, is formed, such that {TAIL ~ surfaces} having different surface indices from a surface index of the substrate are exposed at the ridge and the contact groove 
The layers down to at least the second type conductivity layer are removed to form a ridge and at least one contact groove , which reaches { HEAD ~ the first type conductivity layer } , is formed , such that { TAIL ~ surfaces } having different surface indices from a surface index of the substrate are exposed at the ridge and the contact groove
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH