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arXiv · 1705.01515

Structure and lattice dynamics of the wide band gap semiconductors MgSiN$_{2}$ and MgGeN$_{2}$

M. Råsander·J. B. Quirk·T. Wang·S. Mathew·R. Davies·R. Palgrave·M. A. Moram
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Abstract

We have determined the structural and lattice dynamical properties of the orthorhombic, wide band gap semiconductors MgSiN$_{2}$ and MgGeN$_{2}$ using density functional theory. In addition, we present structural properties and Raman spectra of a MgSiN$_{2}$ powder. The structural properties and lattice dynamics of the orthorhombic systems are compared to wurtzite AlN. We find clear differences in the lattice dynamics between MgSiN$_{2}$, MgGeN$_{2}$ and AlN, for example we find that the highest phonon frequency in MgSiN$_{2}$ is about 100~cm$^{-1}$ higher than the highest frequency in AlN and that MgGeN$_{2}$ is much softer. We also provide the Born effective charge tensors and dielectric tensors of MgSiN$_{2}$, MgGeN$_{2}$ and AlN. Phonon related thermodynamic properties, such as the heat capacity and entropy, are in very good agreement with available experimental results.

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M. Råsander, J. B. Quirk, T. Wang, S. Mathew, R. Davies, R. Palgrave, M. A. Moram. 2017-05-03. Structure and lattice dynamics of the wide band gap semiconductors MgSiN$_{2}$ and MgGeN$_{2}$. https://doi.org/10.1063/1.4985775

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