When the connection is turned on, {HEAD ~ the photodiode} is pinned to {TAIL ~ the substrate}, and kept at a specified potential 
is pinned to
When the connection is turned on , { HEAD ~ the photodiode } is pinned to { TAIL ~ the substrate } , and kept at a specified potential
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH