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Core models of a-edge threading dislocations in wurtzite III(Al,Ga,In)-nitrides



An empirical bond-order many body interatomic Tersoff potential is used for atomistic calculations of the multiple atomic configurations (5/7, 8 and 4) of the a-edge threading dislocations in III(Al,Ga,In)-N compound semiconductors. Structural- and energy-related conclusions are drawn which are attributed to the complexity of the III–III metal type and N–N interactions (bondGa–Ga < bondAl–Al < bondIn–In) in connection with the difference of the lattice parameters (aAlN < aGaN < aInN) and the elastic constants. The 5/7-atomic core configuration is calculated as the most energetically and structurally favourable in all the three compounds. Taking the 5/7-atom model as a reference, the 8-atom core model becomes the next favourable one when the lattice parameter increases (aInN) while the 4-atom core model is the second energetically favourable when the lattice parameter decreases (aAlN).