Towards predictive modeling of near-edge structures in electron energy-loss spectra of AlN-based ternary alloys

abstract

Although the analysis of electron energy loss near-edge structure provides a tool for experimentally probing the density of unoccupied states, a detailed comparison with simulations is necessary in order to understand the origin of individual peaks. This paper presents a density functional theory based technique for predicting the N K edge for ternary (quasibinary) nitrogen alloys by adopting a core hole approach, a methodology that has been successful for binary nitride compounds. It is demonstrated that by using the spectra of binary compounds for optimizing the core hole charge (0.35 e for cubic Ti1-xAlxN and 0.45 e for wurtzite AlxGa1-xN), the predicted spectra evolutions of the ternary alloys agree well with the experiments. The spectral features are subsequently discussed in terms of the electronic structure and bonding of the alloys.

keywords

GROUP-III NITRIDES; AB-INITIO; N-K; LOSS SPECTROSCOPY; STRUCTURE ELNES; CONDUCTION-BAND; DENSITY; STATES; GAN; GROWTH

subject category

Physics

authors

Holec, D; Rachbauer, R; Kiener, D; Cherns, PD; Costa, PMFJ; McAleese, C; Mayrhofer, PH; Humphreys, CJ

Groups

acknowledgements

Financial support by the START Program (Y371) of the Austrian Science Fund (FWF) and by the UK Engineering and Physical Sciences Research Council (EPSRC) is greatly acknowledged.

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