The combination of {HEAD ~ the silicon oxide layer} and {TAIL ~ the silicon layer} comprise, in turn, a composite SRO layer 
The combination of { HEAD ~ the silicon oxide layer } and { TAIL ~ the silicon layer } comprise , in turn , a composite SRO layer
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH