For materials of varying band gap, we compare energy levels atomically localized defects calculated within a semilocal and hybrid density-functional scheme. Since the latter scheme partially relieves gap problem, our study describes how defect shift when approaches experimental value. When suitably aligned, obtained from total-energy differences correspond closely, showing average shifts at most 0.2 eV irrespective gap. Systematic deviations ideal alignment increase with extent wave...

Abstract Hybrid density functional calculations applied to defect charge transition levels are explored in the attempt overcome band‐gap problem of semilocal functionals. Charge a large set point defects calculated with and hybrid functionals found correspond closely when aligned respect average electrostatic potential. This strongly suggests that defined this way already accurately described at these theory. In particular, then also applies energy separation between different levels, which...

Band offsets at semiconductor-oxide interfaces are determined through a scheme based on hybrid density functionals, which incorporate fraction $\ensuremath{\alpha}$ of Hartree-Fock exchange. For each bulk component, the is tuned to reproduce experimental band gap, and conduction valence edges then located with respect reference level. The lineup levels an interface calculation, shown be almost independent $\ensuremath{\alpha}$. Application this...

The authors calculate energy levels associated with the oxygen vacancy in monoclinic HfO2 using a hybrid density functional which accurately reproduces experimental band gap. most stable charge states are obtained for varying Fermi level To compare measured defect levels, they determine total differences specific to considered experiment. Their results show that can consistently account observed (Poole-Frenkel-type) trap assisted conduction, direct electron injection, and optical absorption...

Defect levels of dangling bonds in silicon and germanium are determined within their respective band gaps through the use hybrid density functionals. To validate our approach, we first considered bond finding two well-separated defect excellent correspondence with experimental location. Application to then yields very close lying just above valence band, which is consistent location charge neutrality level. The occurrence negative-$U$ behavior leads a reduced fraction neutral bonds, thereby...

Cesium and methylammonium bismuth iodides (Cs3Bi2I9 MA3Bi2I9) are new low-toxic air stable compounds in the perovskite solar cell family with promising characteristics. Here, electronic structure nature of their optical transitions, dielectric constant, charge carrier properties assessed for photovoltaic applications density functional theory (DFT) calculations experiments. The calculated direct indirect band gap values Cs3Bi2I9 (2.17 2.0 eV) MA3Bi2I9 1.97 found to be good agreement...

We investigate how various treatments of exact exchange affect defect charge transition levels and band edges in hybrid functional schemes for a variety systems. distinguish the effects long-range vs short-range local nonlocal exchange. This is achieved by consideration set four functionals, which comprise semilocal Perdew-Burke-Ernzerhof (PBE) functional, PBE (PBE0), Heyd-Scuseria-Ernzerhof (HSE) derived from PBE0 Coulomb kernel term screened as HSE but which, unlike HSE, does not include...

When described through a plane-wave basis set, the inclusion of exact nonlocal exchange in hybrid functionals gives rise to singularity, which slows down convergence with density sampled $k$ points reciprocal space. In this work, we investigate what extent treatment singularity use an auxiliary function is effective for $k$-point samplings limited density, comparison analogous calculations performed semilocal functionals. Our analysis applies, instance, Brillouin zone at sole...

Poly(ethylene oxide) (PEO) is the most widely used compound as a solid-state (solvent-free) polymer electrolyte for Li batteries, mainly due to its low glass transition temperature (Tg) and ability dissolve salts. It also frequently suggested that cathodic stability renders it possible operate with metal anodes in design of high energy density storage devices. However, little still known about true interfacial chemistry between PEO how these two materials interact each other. We are here...

Oxygen vacancy migration is studied in monoclinic HfO2 and across its interface with SiO2 through density functional calculations. In HfO2, long-range diffusion shows activation barriers of 2.4 0.7eV for the neutral doubly positively charged vacancy, respectively. latter case, preferentially occurs along one-dimensional pathways. A HfO2∕SiO2 model constructed to address O high-κ gate stacks. The shown stabilize charge state upon entering layer.

We calculate charge transition levels of various defects at the SiC/SiO${}_{2}$ interface within a scheme based on hybrid density functionals, which accurately reproduce involved band gaps and offsets. The defect are first evaluated in bulk models components then aligned with respect to diagram through use model showing good structural electronic properties. Interface-specific polarization effects separately classical electrostatics. considered carbon-related involving single atoms dimers...

Abstract Metal adhesion on metal oxides is strongly controlled by the oxide surface structure and composition, but lack of control over conditions often limits possibilities to exploit this in opto- micro-electronics applications heterogeneous catalysis where nanostructural utmost importance. The Cu/ZnO system among most investigated such systems model studies, presence subsurface ZnO defects their important role for have been unappreciated so far. Here we reveal that surface-directed...

Plasmonic materials have optical cross sections that exceed by 10-fold their geometric sizes, making them uniquely suitable to convert light into electrical charges. Harvesting plasmon-generated hot carriers is of interest for the broad fields photovoltaics and photocatalysis; however, direct utilization limited ultrafast thermalization in metals. To prolong lifetime carriers, one can place acceptor materials, such as semiconductors, contact with plasmonic system. Herein, we report effect...

NO2 adsorption at a BaO(100) surface is investigated by means of spin polarized GGA density functional theory. A periodic supercell procedure employed, and two redox reaction channels are mapped out, involving chemisorbed molecules per supercell. The chemisorption studied in subsequent steps. paths initiated the form nitrite over Ba2+ site. This generates an electron hole among surrounding oxygen atoms. path branching occurs as second either (a) acts oxidant, forming nitrite−peroxide pair...

Band offsets of the Ge/GeO2 interface are calculated through a hybrid density functional scheme. We first generate model disordered GeO2 ab initio molecular dynamics to describe oxide component. For addressing interface, we then consider an atomistic in which amorphous is connected crystalline Ge suboxide transition region showing regular structural parameters. The band obtained application alignment scheme, reproduces experimental gaps components. valence offset 3.7 eV favors low-energy...

We provide an explanation for the experimental finding of a dramatically enhanced low-temperature oxygen storage capacity small ceria nanoparticles. At low temperature, octahedral nanoparticles will be understoichiometric at both oxidizing and reducing conditions without showing explicit vacancies. Instead, rather than becoming stoichiometric conditions, such particles are stabilized through adsorption forming superoxo (O2(-)) ions become in this way supercharged with oxygen. The...

The determination of band alignments and defect levels is demonstrated for the technologically relevant Si–SiO2–HfO2 gate stack. proposed scheme, which combines first-principles molecular dynamics model generation hybrid density functionals electronic-structure calculations, yields offsets in close agreement with experiment. Charge transition pinning associated oxygen vacancies are aligned respect to silicon edges. shown preferentially reside amorphous layer, consistent experimental...

Using a density functional approach, we study structural and electronic properties of the $4H(0001)\text{\ensuremath{-}}\mathrm{SiC}∕{\mathrm{SiO}}_{2}$ interface. Through sequential use classical ab initio simulation methods, generate an abrupt model structure which describes transition between crystalline $\mathrm{SiC}$ amorphous ${\mathrm{SiO}}_{2}$ without showing any coordination defect. The first step in our generation procedure consists identifying suitable interfacial bonding...

We investigate carbon single-atom and pair defects at the SiC/SiO${}_{2}$ interface as candidate for density of defect states in SiC band gap. In order to accurately describe electronic levels with respect edges, we use a hybrid functional which reproduces experimental gap SiC. The consisting two neighboring ${\mathit{sp}}^{2}$ hybridized atoms is modeled various configurations within model showing good structural parameters an oxide typical amorphous SiO${}_{2}$. found contribute not only...

We have developed an efficient scheme for the generation of accurate repulsive potentials self-consistent charge density-functional-based tight-binding calculations, which involves energy-volume scans bulk polymorphs with different coordination numbers. The was used to generate optimized parameter set various ZnO polymorphs. new potential subsequently tested bulk, surface, and nanowire systems as well water adsorption on low-index wurtzite (101̅0) (112̅0) surfaces. By comparison results...

Using a combination of characterisation techniques including 3D electron diffraction (3D ED) and powder X-ray diffraction, we reveal that the long-believed hexagonal Na 2 ZrO 3 , is, in fact, with three different types structural disorder.

Metal anodes provide the highest possible energy density in batteries. However, challenges associated with electrode/electrolyte interface side reactions and dendrite growth remain unsolved, especially under fast-charging conditions. In this paper, we consider a phase-field model of electrodeposition optimize its parameters for suppressing accelerating charging speed constant voltage. We identify interfacial mobility as key parameter, which should be maximized to inhibit dendrites without...