UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2011 Meeting


Section: Solid State Physics and Materials Science


Title:
THEORETICAL INVESTIGATION OF POINT DEFECTS IN ALUMINUM NITRIDE NANOWIRES


Authors:
Adela Nicolaev(1), T. L. Mitran(1), G.A. Nemnes(1),L. ION(1), St. Antohe(1)


Affiliation:
1) University of Bucharest, Physics Department, 405 Atomistilor, POB MG-11, 077125, Magurele-Ilfov, Romania


E-mail
adela@solid.fizica.unibuc.ro


Keywords:
defects, nanowires, ab initio, formation energy


Abstract:
Group III nitride materials are being intensively researched due to their demonstrated success in optoelectronic devices and their further potential in electronic and optoelectronic applications. Aluminium nitride is a semiconductor with a wide band gap (6.2 eV), a large exciton binding energy and a very small electron affinity. During the growth process, several defects may appear, such as point defects or threading dislocations that induce deep levels in the band gap. These types of defects lead to the reduction of the devices performance. Particularly, AlN nanowires hold great promise for nanotechnology applications because of the large band gap and structural confinement properties and are being investigated for their use in light-emitting diodes, nanowire lasers and potential spintronic devices. Therefore, it is important to know how structural defects affects their electrical and/or optical properties. Theoretical studies can provide a better understanding of the electronic and structural properties of defective nanostructures. Unfortunately, there have been only a few theoretical ab initio studies of defects in AlN structure. That is why, in this work we present a study of some point defects in AlN nanowires, including vacancies, interstitial extrinsic defects using ab initio calculations. We have performed density-functional pseudopotential calculations to investigate the electronic structure, atomic configurations, formation energies of native point defects and impurities in AlN, as well as their defect-to-band transition energies. A discussion about the local atomic configuration of the investigated defects and on their ability to act as efficient dopants is given.