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