Structure-derived electronic and optical properties of transparent conducting oxides

Segev, David; Wei, Su‐Huai

doi:10.1103/physrevb.71.125129

Cited by 127 publications

(86 citation statements)

References 29 publications

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“…The corresponding band gaps ( g E ) were determined for both of the compounds (Table I) In order to understand whether the considered compounds remain transparent in the visible spectra even after heavy doping by shallow donors, the difference in the energies between the CB minimum and the second nearest CB s g E has been calculated (Table I) known also as the second band gap. 24 The analysis shows that the value of s g E for ZnSiO 3 -r is ~2.8 eV. Consequently, if and Zn 2 SiO 4 the CB minimum is located at the Γ point (see Fig.…”

Section: Band Structurementioning

confidence: 99%

“…Consequently, CB electrons are lighter than holes and hence the influence of the latter on the electrical conductivity will be minimal. For quantitative characterization of carrier mobility the calculated effective masses around the bottommost CB extremes are given in Table II 24 Consequently, the mobility of CB electrons as well the electrical conductivity in Zn 2 SiO 4 -r is expected to be small.…”

Section: Conduction Band Effective Massesmentioning

confidence: 99%

“…22 Fayalites M 2 SiO 4 (M = Fe and Co) have been investigated 23 by the generalized-gradient approximation (GGA) with the multiorbital mean-field Hubbard potential (U). The related compounds Zn 2 SnO 4 , Cd 2 SnO 4 , and In 2 CdO 4 have been examined 24 by VASP. Possibility of phase transitions between structural polymorphs of ZnSiO 3 and Zn 2 SiO 4 have been reported 25 by DFT calculations using the VASP package.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Electronic structure and optical properties of ZnSiO3 and Zn2SiO4

Karazhanov

Ravindran

Fjellvåg

et al. 2009

Journal of Applied Physics

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The electronic structure and optical properties of orthorhombic, monoclinic, and rhombohedral (corundum type) modifications of ZnSiO 3 , and of rhombohedral, tetragonal, and cubic (spinel type) modifications of Zn 2 SiO 4 have been studied using ab initio density functional theory calculations. The calculated fundamental band gaps for the different polymorphs and compounds are in the range 2.22 -4.18 eV. The lowest conduction band is well dispersive similar to that found for transparent conducting oxides such as ZnO. This band is mainly contributed by Zn 4s electrons. The carrier effective masses were calculated and compared with those for ZnO.The topmost valence band is much less dispersive and contributed by O 2p and Zn 3d electrons.From the analysis of charge-density, charges residing in each sites, and electron localization function it is found that ionic bonding is mainly ruling in these compounds. The calculated optical dielectric tensors show that the optical properties of ZnSiO 3 and Zn 2 SiO 4 are almost isotropic in the visible part of the solar spectra and depend negligibly on the crystal structure. Within the 0-4 eV photon energy range the calculated magnitude of the absorption coefficient, reflectivity, refractive index, and extinction coefficient are smaller than 10 3 cm -1 , 0.15, 2.2, and 0.3, respectively for all 2 the ZnSiO 3 and Zn 2 SiO 4 phases considered in this work. This suggests that zinc silicates can be used as antireflection coatings. 71.15.-m; 71.22.+i PACS:

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Section: Band Structurementioning

confidence: 99%

Section: Conduction Band Effective Massesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electronic structure and optical properties of ZnSiO3 and Zn2SiO4

Karazhanov

Ravindran

Fjellvåg

et al. 2009

Journal of Applied Physics

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“…This enables doped CdO to be rather transparent at visible frequencies, even though the fundamental band gap would seem to be too low to allow this. In some other TCOs such as In 2 O 3 [135,170,192] [194] symmetry dictates that interband transitions between the top valence bands and the bottom conduction band are either dipole forbidden or have only minimal dipole matrix elements, as represented for In 2 O 3 in Fig. 14(a).…”

Section: Transparencymentioning

confidence: 99%

Conductivity in transparent oxide semiconductors

King

Veal

2011

J. Phys.: Condens. Matter

224

180

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Abstract. Despite an extensive research effort for over 60 years, an understanding of the origins of conductivity in wide band-gap transparent conducting oxide (TCO) semiconductors remains elusive. While TCOs have already found widespread use in device applications requiring a transparent contact, there are currently enormous efforts to (i) increase the conductivity of existing materials, (ii) identify suitable alternatives, and (iii) attempt to gain semiconductor-engineering levels of control over their carrier density, essential for the incorporation of TCOs into a new generation of multifunctional transparent electronic devices. These efforts, however, are dependent on a microscopic identification of the defects and impurities leading to the high unintentional carrier densities present in these materials. Here, we review recent developments towards such an understanding. While oxygen vacancies are commonly assumed to be the source of the conductivity, there is increasing evidence that this is not a sufficient mechanism to explain the total measured carrier concentrations. In fact, many studies suggest that oxygen vacancies are deep, rather than shallow, donors, and their abundance in as-grown material is also debated. We discuss other potential contributions to the conductivity in TCOs, including other native defects, their complexes, and in particular hydrogen impurities. Convincing theoretical and experimental evidence is presented for the donor nature of hydrogen across a range of TCO materials, and while its stability and the presence of interstitial and substitutional species are still somewhat open questions, it is one of the leading contenders for unintentional conductivity in TCOs. We also review recent work indicating that the surfaces of TCOs can support very high carrier densities, opposite to the case of conventional semiconductors. In thin-film materials/devices and, in particular, nanostructures, the surface can have a large impact on the total conductivity in TCOs. We discuss models that attempt to explain both the bulk and surface conductivity based on features of the bulk band structure common across the TCOs, and compare these materials to other semiconductors. Finally, we briefly consider transparency in these materials, and its interplay with conductivity. Understanding this interplay, as well as the microscopic contenders for the conductivity of these materials, will prove essential to the future design and control of TCO semiconductors, and their implementation into novel multifunctional devices.

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“…[30][31][32] Numerous experimental and theoretical studies have investigated the structural, electrical, and optical properties of ZTO. 27,33,34 The magnetic properties of TM-doped ZTO have received far less attention, and the mechanism of magnetism in ternary oxides may differ from that in binary oxides. Mn is an attractive TM-dopant because of its d 5 electron configuration and large magnetic moment.…”

Section: Introductionmentioning

confidence: 99%