Since in the wurtzite structure of AlN and InN the second-neighbor distance was very close to the stable so-called metallic Al-Al and In-In distances respectively, a III-species environment approach based on a Tersoff empirical bond order interatomic potential was developed in which the cut-off distance for Al-Al and In-In interactions was tuned. In particular, the work was focused on two issues: the development of an approach for the calculation of defected structures in III-nitrides and the application of this method on a series of planar defects in wurtzite structure. Various structural and energy-related conclusions were drawn that were attributed to the complexity of the III-III metal type and N-N interactions in connection with the difference of the lattice parameters and the elastic constants. Molecular dynamic simulations were led to the conclusion that structural transformations may also occur. The Austerman-Gehman and Holt models for the inversion domain boundary on the (10•0) plane were higher in energy than the IDB* model of Northrup, Neugebauer and Romano. The model of Blank et al. for the translation domain boundary on the {1¯2•0} plane was unstable with respect to Drum's model. The Austerman model for the inversion domain boundary on the {1¯2•0} plane was unstable with respect to the IDB* model appropriate for this plane. The Austerman {10•0} inversion domain boundary model was recognized as a strong candidate, among the inversion domain boundary atomic configurations. Moreover, models for inversion domain boundaries on {10•0} planes in which the boundary plane intersects two bonds (type-2 models) were less stable than models in which the boundary plane intersects one bond (type-1 models), in all cases considered. It was confirmed that the III-species environment approach describes the so-called wrong-bonded defect local configuration structures more realistically with respect to the standard approach.

Interatomic Potential Calculations of III(Al,In)-N Planar Defects with a III-Species Environment Approach. J.Kioseoglou, P.Komninou, T.Karakostas: Physica Status Solidi B, 2008, 245[6], 1118-24

[295] Stacking Fault Formation in Semiconductors

A simple scheme was used to calculate the energies of stacking faults, polytypes, and arbitrary stacking sequences in elementary and compound semiconductors. The scheme was based upon the calculation of 2 elementary energies, which could be obtained, for each material, from the computed difference of energy between its cubic and hexagonal modifications and from the measured or computed energy of a single kind of stacking fault. Formulae were given for faults in both zincblende and wurtzite structures and for the stacking sequences that occurred during the transformation of one phase into the other. This applied, in particular, to nanowires; where such faults and sequences were frequently encountered.

A Simple Calculation of Energy Changes upon Stacking Fault Formation or Local Crystalline Phase Transition in Semiconductors. F.Glas: Journal of Applied Physics, 2008, 104[9], 093520