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