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