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First-principles study of II-IV-N2 compounds

Lyu, Sai
http://orcid.org/0000-0002-8166-6052
http://rave.ohiolink.edu/etdc/view?acc_num=case1553701112205839

Abstract Details

, Doctor of Philosophy, Case Western Reserve University, Physics.
The II-IV-N2 semiconductors can be conceptually derived from the group-III nitrides and are useful to complement the nitride semiconductor family. The Cd-IV-N2 and Be-IV-N2 compounds with IV equals Si, Ge, and Sn in Pbn21 structure are studied in this dissertation. These Cd-IV-N2 compounds have not been synthesized yet. From first-principles calculations, their lattice parameters are obtained and the electronic band structure are determined in density functional theory and more accurate quasiparticle self-consistent GW method. Although these compounds are metastable based on the calculations of formation energies, it might still be possible to synthesize them provided that an activated source of N is used. The electronic band structures for BeSiN2 and BeGeN2 are also determined. For MgGeN2 and MgSnN2, we find that the inclusion of Ge-3d and Sn-4d semicore orbitals in the basis set leads to a reduction of the gap compared to previous work. The calculations of phonons at the Brillouin zone center in Cd-IV-N2 compounds are carried out. The longitudinal optical-transverse optical splittings are determined using Born effective charges. These are used to simulate Raman spectra and infrared spectra. Phonon densities of states and their resolution by atom contribution are also presented. Using density functional perturbation theory, the elastic and piezoelectric constants of Cd-IV-N2 compounds are also reported. We also calculated the spontaneous polarizations. The second-order nonlinear optical coefficients in the static limit are evaluated using density functional perturbation theory from the electronic response to a static electric field for the group-III nitrides and several II-IV-N2 ternary nitrides. They are compared with literature results using the sum over states approach including local field effects.
Walter RL Lambrecht (Advisor)
Physics

Recommended Citations

Citations

  • Lyu, S. (n.d.). First-principles study of II-IV-N2 compounds [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1553701112205839

    APA Style (7th edition)

  • Lyu, Sai. First-principles study of II-IV-N2 compounds. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1553701112205839.

    MLA Style (8th edition)

  • Lyu, Sai. "First-principles study of II-IV-N2 compounds." Doctoral dissertation, Case Western Reserve University. Accessed MAY 10, 2024. http://rave.ohiolink.edu/etdc/view?acc_num=case1553701112205839

    Chicago Manual of Style (17th edition)

case1553701112205839
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This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.