Intrinsic interstitial and antisite defects in GaN were studied by using density functional theory, and their configurations, electronic structures, and bonding properties were characterized by using the Wannier function. All N interstitial configurations eventually transform into N–N split interstitials, between which two π orbitals existed. The relaxation of a Ga antisite defect also leads to the formation of a N–N split configuration; however, its local Wannier orbitals were remarkably different from the N–N split interstitial. The different local Wannier orbitals around Ga interstitial configurations demonstrated that Ga interstitials were critical defects in GaN. The most striking feature was that Ga–Ga<11▪0> split interstitials could bridge the gap between non-bonded Ga atoms, thereby leading to a chain of four metallic-like-bonded Ga atoms along the <11▪0> direction in GaN, which may exhibit quantum properties.

Wannier Orbitals and Bonding Properties of Interstitial and Antisite Defects in GaN. F.Gao, E.J.Bylaska, A.El-Azab, W.J.Weber: Applied Physics Letters, 2004, 85[23], 5565-7