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