The TFT 6, wherein when the first impurity is a group V recipient {HEAD ~ the second impurity} is {TAIL ~ a group III donor} 
The TFT 6 , wherein when the first impurity is a group V recipient { HEAD ~ the second impurity } is { TAIL ~ a group III donor }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL