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