For some embodiments, {TAIL ~ the carbon nanotubes} may be concentrated near {HEAD ~ the source/drain regions} 
For some embodiments , { TAIL ~ the carbon nanotubes } may be concentrated near { HEAD ~ the source / drain regions }
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD