In a preferred embodiment, {HEAD ~ the LED} has {TAIL ~ double heterojunction structure} having a semiconductor active layer between two confinement layers 
has
In a preferred embodiment , { HEAD ~ the LED } has { TAIL ~ double heterojunction structure } having a semiconductor active layer between two confinement layers
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH