Electronic structure of rutile SnO2, GeO2 and TeO2

Tin dioxide from first principles: Quasiparticle electronic states and optical properties

“…26,28 The agreement of a VBM of Γ + 3 also settled the symmetry assignment of the Sn s-derived conduction-band minimum (CBM) as Γ + 1 , as suggested by experimental arguments 13,14,29 and calculations. 9,11 The experimental results largely agree that the lowest dipole-allowed direct (direct-allowed) transition features a strong polarization anisotropy, but the origin of this transition is heavily debated. Experimental 10 as well as theoretical [7][8][9]11 reports are plagued by inconsistencies in the ordering and relative energies of the lower-lying VB states.…”

“…9,11 The experimental results largely agree that the lowest dipole-allowed direct (direct-allowed) transition features a strong polarization anisotropy, but the origin of this transition is heavily debated. Experimental 10 as well as theoretical [7][8][9]11 reports are plagued by inconsistencies in the ordering and relative energies of the lower-lying VB states. Nagasawa and Shionoya reported an allowed transition value of 3.75 eV for light polarized perpendicular to the tetragonal c axis (E ⊥ c), which they associated with a VB of symmetry Γ − 5 lying 0.15 to 0.20 eV below the VBM.…”

“…Despite the vast experimental and theoretical literature on SnO 2 , many discrepancies and unsolved issues remain. These include details of the valence-band (VB) ordering and band symmetries, 7-10 the role of indirect transitions, 9,11,12 and the exciton spectrum. 10,[13][14][15] Although SnO 2 is widely used for its optical properties, its dielectric function is not available in the literature.…”

“…[22][23][24] Up until now no theoretical band structure is capable of explaining all experimental facts for SnO 2 . The earliest self-consistent calculations for SnO 2 , employing the augmented-plane-wave 11 and linearized muffin-tin orbital 9 methods, along with more recent ones in the augmented-spherical-wave 12 method, predicted an indirect gap with the VBM at the R point instead of Γ. Tightbinding calculations by Robertson 8 seemed more consistent with the experimental interpretations of a direct gap and highestlying VB symmetry assignments, by showing a VB of the suggested symmetry Γ − 5 approximately 0.2 eV below the VBM. 15,[22][23][24] However, the next lower VB in Robertson's calculations was at −0.8 eV, which cannot explain the experimentally observed absorption onsets and interpretations.…”

Optical properties of germanium dioxide in the rutile structure

“…The tetragonal and trigonal crystalline forms differ substantially in their chemical properties, especially solubility, in their densities and indices of refraction. Over the past three decades various physical and thermodynamical properties of rutiletype GeO 2 have been investigated: elastic properties [5], compressibility [6], entropy and enthalpy [7], thermal expansion [8], structure [9], melting phenomena [10], electronic properties [11][12][13][14][15][16] and high-pressure behavior [18].…”