If the layer is too thick {HEAD ~ the advantage} of {TAIL ~ confinement} is lost, and if the layer is too thin carrier spillover may occur, both of which contribute negatively to the efficacy of a solid state lighting source 
of
If the layer is too thick { HEAD ~ the advantage } of { TAIL ~ confinement } is lost , and if the layer is too thin carrier spillover may occur , both of which contribute negatively to the efficacy of a solid state lighting source
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH