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RESEARCH PRODUCT

LCAO calculation of neutral defects in GaN

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description

Four well known HF, LDA, GGA and B3LYP Hamiltonians in LCAO approximation have been used in band structure calculations to obtain the main properties of the perfect GaN crystal with hexagonal lattice (C space group). Calculated lattice parameters, elastic constants and the band gap have been compared with the experimental data and the results of other calculations. As a consequence, the GGA Hamiltonian has been chosen, giving the lattice parameters a = 3.20 A, c = 5.20 A, u = 0.377, the bulk modulus B = 206 GPa and the energy gap Eg = 2.7 eV. These results reasonably reproduce the experimental data. For the point defects calculation (VGa, VN, MgGa, ZnGa, CN, and SiN) the supercell model was applied .The shape and size of supercell influence on the results was investigated. It was found that the supercell of 96 atoms ensures the reasonable agreement with the band structure calculations for perfect crystal and weak defect-defect interaction between the images of point defect in the periodic model. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)