The carbon nanotubes may extend across the entire channel region or {TAIL ~ a portion} of {HEAD ~ the channel region} 
The carbon nanotubes may extend across the entire channel region or { TAIL ~ a portion } of { HEAD ~ the channel region }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD