I. Belabbas
École nationale supérieure d'ingénieurs de Caen
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Featured researches published by I. Belabbas.
Philosophical Magazine | 2006
I. Belabbas; P. Ruterana; J. Chen; G. Nouet
The atomic and electronic properties of dislocations in III–N semiconductor layers, especially GaN, are presented. The atomic structure of the edge threading dislocation is now well established with three different cores (8 or full core, 5/7 or open core, and 4-atom ring). The use of atomistic simulations has confirmed these atomic structures and has given a good understanding of the electronic structure of the screw dislocation. Partial dislocations which are mostly confined in the area close to the substrate are now also being investigated. It is becoming clear that the electrical activity of all these defects is dependent on the layer quality, which is governed by the growth conditions.
Journal of Applied Physics | 2011
J. Kioseoglou; Efterpi Kalesaki; I. Belabbas; J. Chen; G. Nouet; H. Kirmse; W. Neumann; Philomela Komninou; Theodoros Karakostas
Density functional theory calculations were performed on undoped AlN screw threading dislocations (TDs) as well as TDs doped by indium and oxygen, prompted by integrated experiments through transmission electron microscopy and spectroscopic techniques demonstrating enhanced In and O concentrations in screw dislocation cores. It is revealed that screw TDs act as conduction pathways to charge carriers, introducing multiple levels in the bandgap due to overstrained, dangling, and “wrong” bonds formed even in the undoped cores. The presence of impurities and especially metallic In elevates the metal-like electronic structure of the distorted material and promotes the conductivity along the dislocation line. Hence screw dislocations in AlN are established as highly prominent conductive nanowires in semiconducting thin films and prospects for novel, highly functional nano-device materials through exploitation of screw TDs are attested.
Rare Metals | 2006
I. Belabbas; Jun Chen; P. Ruterana; Guanghui Yu; G. Nouet
The atomic and electronic structures of the c threading dislocations with an edge or screw character were compared using a tight binding formalism which takes into account charge transfer. The two dislocations do not exhibit dangling bonds. While the screw dislocation contains only constrained Ga-N bonds, the edge dislocation contains Ga-Ga and N-N wrong bonds. Both dislocations are found to induce shallow and deep gap states.
Physical Chemistry Chemical Physics | 2018
Konstantinos Termentzidis; Mykola Isaiev; Anastasiia Salnikova; I. Belabbas; David Lacroix; J. Kioseoglou
We report on thermal transport properties of wurtzite GaN in the presence of dislocations, by using molecular dynamics simulations. A variety of isolated dislocations in a nanowire configuration were analyzed and found to reduce considerably the thermal conductivity while impacting its temperature dependence in a different manner. We demonstrate that isolated screw dislocations reduce the thermal conductivity by a factor of two, while the influence of edge dislocations is less pronounced. The relative reduction of thermal conductivity is correlated with the strain energy of each of the five studied types of dislocations and the nature of the bonds around the dislocation core. The temperature dependence of the thermal conductivity follows a physical law described by a T
MRS Proceedings | 2005
I. Belabbas; G. Nouet; A. Béré; J. Chen; S. Petit; M.A. Belkhir; P. Ruterana; Ph. Komninou
^{-1}
Physical Review B | 2007
I. Belabbas; A. Béré; J. Chen; S. Petit; M. Akli Belkhir; P. Ruterana; G. Nouet
variation in combination with an exponent factor which depends on the materials nature, the type and the structural characteristics of the dislocations core. Furthermore, the impact of the dislocations density on the thermal conductivity of bulk GaN is examined. The variation and even the absolute values of the total thermal conductivity as a function of the dislocation density is similar for both types of dislocations. The thermal conductivity tensors along the parallel and perpendicular directions to the dislocation lines are analyzed. The discrepancy of the anisotropy of the thermal conductivity grows in increasing the density of dislocations and it is more pronounced for the systems with edge dislocations.
Computational Materials Science | 2006
I. Belabbas; M.A. Belkhir; Young Hee Lee; J. Chen; A. Béré; P. Ruterana; G. Nouet
Here we present results on the first atomic simulation of the threading − + ) ( c a r r mixed dislocation cores in wurtzite GaN. These calculations are based on a modified Stillinger-Weber potential. For this dislocation two core configurations are shown to be stable, one with a complex double 5/6-atoms rings and the other with a 5/7-atom rings structures. These two cores do not contain wrong bonds.
Computational Materials Science | 2013
I. Belabbas; J. Chen; Ph. Komninou; G. Nouet
Physica Status Solidi (c) | 2006
I. Belabbas; J. Chen; M. Akli Belkhir; P. Ruterana; G. Nouet
Physica Status Solidi (c) | 2007
I. Belabbas; A. Béré; J. Chen; P. Ruterana; G. Nouet