Electronic structure of 1/6〈202¯3〉 partial dislocations in wurtzite GaN (original) (raw)

Atomic structures and energies of partial dislocations in wurtzite GaN

Physical Review B, 2004

The atomic structures of 1 / 6͗2023͘ partial dislocations delineating the I 1 intrinsic basal stacking fault in wurtzite GaN are modelled using an empirical interatomic potential in combination with anisotropic elasticity calculations. Twelve stable configurations are obtained for each polarity, and their core radii, energies, and atomic configurations are given. The 5 / 7-atom ring core in which the atoms are tetrahedrally coordinated is found energetically favorable among the edge dislocation configurations. For the mixed type partials, 5 / 7-and 12-atom rings are obtained as low-energy cores, but none of them is found to comprise only tetrahedrally coordinated atoms. Each of them is found energetically favorable under distinct structural conditions.

9 SCIENTIFIC HIGHLIGHT OF THE MONTH Partial dislocations in wurtzite GaN

2000

The atomic structures and energies of 1=6 < 2023 > and 1=3 < 1010 > partial dislocations in wurtzite GaN are modelled using an empirical interatomic potential in combination with topological theory and anisotropic elasticity calculations. Twelve stable congurations of the 1=6 < 2023 > edge and mixed partial dislocations that bound I1 intrinsic basal stacking faults are obtained for

Partial dislocations in wurtzite GaN

Physica Status Solidi (a), 2005

The partial dislocations in wurtzite-structured GaN are reviewed and new results are presented. A multiplicity of partials is possible depending on stacking fault (SF) type, orientation, and interactions. The partials that delimit the I1 intrinsic basal SFs have 5/7, 8, or 12-atom cores as more probable configurations. The core structures of 90° partial dislocations with 1/6〈203〉 Burgers vector were studied from high resolution transmission electron microscopy observations in comparison with simulated models obtained from energetic calculations. Two cases were distinguished with one structure involving a 5/7 or 12-atom ring core and the other an 8-atom ring core. Another type of partials, in particular dislocations accommodating mirror variants of basal SFs were also studied experimentally. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Atomistic Simulation of Undissociated 60&deg ; Basal Dislocation in Wurtzite GaN

Modeling and Numerical Simulation of Material Science, 2013

We have carried out computer atomistic simulations, based on an efficient density functional based tight binding method, to investigate the core configurations of the 60°basal dislocation in GaN wurtzite. Our energetic calculations, on the undissociated dislocation, demonstrate that the glide configuration with N polarity is the most energetically favorable over both the glide and the shuffle sets.

Atomic core configurations of the -screw basal dislocation in wurtzite GaN

Journal of Crystal Growth, 2007

The results of atomistic calculations based on an ab initio tight-binding method are reported in this work for four configurations of the perfectã-screw basal dislocation in wurtzite GaN: pure shuffle, pure glide and two mixed shuffle-glide. Configurations with pure character (shuffle or glide) are found to be stable, whereas those with mixed shuffle-glide character are found to be transition-like configurations. Further, the calculations predict that the pure glide configuration, containing threefold coordinated atoms with an sp 2 hybridization, to be the most energetically favourable. r

A theoretical approach for the dislocation reduction of wurtzite InxGa1−xN/GaN heteroepitaxy

2012 7th International Conference on Electrical and Computer Engineering, 2012

This paper reports the numerical estimation of misfit dislocation in wurtzite In x Ga 1-x N/GaN heterostructure. The misfit strain increases with the increase of lattice mismatch for higher In content. The exponential grading technique has been modelled for the reduction of dislocation. An energy balance model has been modified to evaluate the misfit dislocation density. The dislocation density has been reduced from 68.07*10^9 cm -2 to 0.288*10^6 cm -2 which is tapered in nature and help to promote annihilation and coalescence reactions between threading dislocations without unwanted tangling and pinning events. Finally, a comparative analysis has also been shown between without graded layer having constant composition and exponentially graded layer In 0.2 Ga 0.8 N/GaN.

Ab-initio tight-binding study of the core structures of the c -edge dislocation in wurtzite GaN

physica status solidi (a), 2006

In the framework of ab-initio tight-binding methods, we modelled and studied the atomic and electronic core structures of the c-edge basal dislocation in wurtzite GaN. We found this dislocation to have four core configurations displaying 5/8/5-or 4/8-atom rings structures. All these configurations induce unfilled deep states in the top half of band gap.

Energetics of the 30 ∘ Shockley partial dislocation in wurtzite GaN

Superlattices and Microstructures, 2006

In the present work, we have investigated the relative energy of different core configurations of the 30∘ Shockley partial dislocation in wurtzite GaN. By using a modified Stillinger–Weber potential, we have carried out large scale calculations on models containing many thousands of atoms. Both glide and shuffle configurations have been considered within the two core polarities (Ga, N). Similarly to what was reported for conventional semiconductors, our calculations showed that the reconstructed glide configurations are energetically favoured over the shuffle ones.

Atomic structure and energy of threading screw dislocations in wurtzite GaN

physica status solidi (c), 2005

Atomic structure and energy of the screw dislocation b=<000c> in the full core configuration has been investigated with a self-consistent density functional tight binding calculation. A 288-atom cluster was used and the dangling bonds saturated with pseudo-hydrogen. The line energy is comparable to the values obtained using a supercell.