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Theoretical study of the substitutional Vanadium – Nitrogen vacancy complex in AlN

Supervisor:               Viktor Ivády

Level:                       adaptable to Bachelor or Master level

Prerequisites:           Physics of condensed matter I (TFFY70)

    Quantum Mechanics (TFFY54)

Aluminum nitride is a wide band gap semiconductor, which has high importance in ultraviolet photonic applications, f. g. in the realization of ultraviolet LEDs. The investigation of the influence of transitional metal impurities on the electric and optical properties of AlN is crucial for such applications.

On the other hand, the theoretical description of transitional metal point defects in AlN is problematic due to the different character of the localized d-like defect states and the delocalized sp3-like states of the host crystal.

In this diploma project the candidate will work on the following tasks: determine the ground state properties, such as geometry, electron structure, spin state and charge density (see FIG. 1), of the point defect complex of substitutional Vanadium and nitrogen vacancy (VAl–VacN) in AlN by the means of first principle calculation in the framework of hybrid density functional theory (hybrid-DFT). The accuracy of the approximations used in this scheme are questionable for VAl–VacN, therefor the candidate should examine the exactness of the outcomes by invoking the generalized Koopman’s and Janak’s theorems. If it is necessary, a correction of the localized orbitals should be carried out by the correction scheme (HSE06+Vw) developed at Linköping University. The effect of the correction should be investigated by determining the change of the geometry and the localized orbitals of the defect.

Participant of this diploma project can acquire the basic knowledge concerning the host material AlN and somewhat detailed knowledge related to the theoretical description of point defects in semiconductors.

FIG. 1. Different views of the charge density of the localized orbitals of NSi-VC defect in 4H-SiC.

Responsible for this page: Fei Wang

Last updated: 01/02/14