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