wherein the first, second and third semiconductor layers are formed of a non single crystal semiconductor doped with a dangling bond neutralizer; the first and third semiconductor layers have the same conductivity type; and {HEAD ~ the second semiconductor layer} has {TAIL ~ a higher resistivity} than the first and third semiconductor layers; and 
has
wherein the first , second and third semiconductor layers are formed of a non single crystal semiconductor doped with a dangling bond neutralizer ; the first and third semiconductor layers have the same conductivity type ; and { HEAD ~ the second semiconductor layer } has { TAIL ~ a higher resistivity } than the first and third semiconductor layers ; and
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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH