a third semiconductor layer formed on the second semiconductor layer in {TAIL ~ exactly the same size} and {HEAD ~ pattern} as the latter 
a third semiconductor layer formed on the second semiconductor layer in { TAIL ~ exactly the same size } and { HEAD ~ pattern } as the latter
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH