ERBIUM IN Si AND GaN: EXTENDED VERSUS POINT DEFECTS

Extended x-ray absorption fine structure measurements show that Er defects in O-poor Si closely resemble bulk Er sub 3 Si sub 5 with long ErBSi bonds, while in GaN, regardless of O content, Er substitutes for Ga sites as point defects with unusually short ErBN bonds. The structure and energetics of these two systems were examined in a series of density functional theory calculations. The detailed findings and excellent agreement with the data provide new insight into the origin of this very different Er-doping behavior.