Simulations of dislocation core in pyramidal plane of n- and p-doped wurtzite GaN and AlGaN
IG Batyrev and NS Weingarten and KA Jones, PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS, 254, 1600736 (2017).
We present results of classical and quantum atomistic simulations of two dislocation core structures of mixed dislocations in a pyramidal plane of wurtzite GaN and AlGaN. We also studied the distribution of n- (Si) and p- (Mg) dopants relative to the dislocation core in the pyramidal plane. A Tersoff-type interatomic potential is used to generate and relax two fully periodic systems containing hundreds of atoms, and one of the final configurations was relaxed using density functional theory (DFT). We studied trends for segregation around the dislocation core of n-dopant Si atoms and p-dopant Mg atoms using DFT and a simulation cell containing 1448 atoms with a dislocation dipole to provide periodic boundary conditions. Presumably, the segregation of the dopants relieves the stress accumulated in the dislocation cores. We also simulated various distributions of Al in AlGaN with 27% of Al near the dislocation core to understand thermodynamic trends in distribution of Al atoms. Our calculations indicate that atoms of Al randomly distributed in AlGaN with no discernible segregation to the dislocation core. X-ray diffraction (XRD) spectra were simulated for the dislocations in the pyramidal plane using the virtual diffraction method. (C) 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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