A semiconductor layer with {TAIL ~ a doping} of a second conductivity type is applied at {HEAD ~ a surface} of the semiconductor substrate 
A semiconductor layer with { TAIL ~ a doping } of a second conductivity type is applied at { HEAD ~ a surface } of the semiconductor substrate
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH