{TAIL ~ The drain region}, {HEAD ~ the source/base region}, and the cathode region have a second conductivity type 
{ TAIL ~ The drain region } , { HEAD ~ the source / base region } , and the cathode region have a second conductivity type
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH