An impurity concentration C is {TAIL ~ the optimum concentration} of {HEAD ~ lightly doped diffusion regions} that achieves the lowest hot carrier effect 
An impurity concentration C is { TAIL ~ the optimum concentration } of { HEAD ~ lightly doped diffusion regions } that achieves the lowest hot carrier effect
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH