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Alfredo Pasquarello

Cette personne a quitté l’EPFL

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Publications associées (154)

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Accurate and efficient band-gap predictions for metal halide perovskites at finite temperature

Alfredo Pasquarello, Patrick Gono, Thomas Bischoff, Haiyuan Wang

We develop a computationally efficient scheme to accurately determine finite-temperature band gaps for metal halide perovskites belonging to the class ABX(3) (A = Rb, Cs; B = Ge, Sn, Pb; and X = F, Cl, Br, I). First, an initial estimate of the band gap is ...

NATURE PORTFOLIO2022

Defect levels of carbon-related defects at the SiC/SiO2 interface from hybrid functionals

Alfredo Pasquarello, Peter Broqvist, Audrius Alkauskas, Fabien Devynck

We investigate carbon single-atom and pair defects at the SiC/SiO2 interface as candidate defects for the density of defect states in the SiC band gap. In order to accurately describe the electronic defect levels with respect to the SiC band edges, we use ...

2011

Nitrogen fixation at passivated Fe nanoclusters supported by an oxide surface: Identification of viable reaction routes using density functional calculations

Alfredo Pasquarello, Harald Brune

Using density-functional calculations, we investigate the possibility of ammonia synthesis at supported Fe nanoclusters along catalytic routes closely resembling those in biological nitrogen fixation. To achieve similar catalytic conditions as at the activ ...

2009

Metal adatoms on graphene and hexagonal boron nitride: Towards rational design of self-assembly templates

Alfredo Pasquarello, Oleg Yazyev

Periodically corrugated epitaxial graphene and hexagonal boron nitride (h-BN) on metallic substrates are considered as perspective templates for the self-assembly of nanoparticles arrays. By using first-principles calculations, we determine binding energie ...

2010

Origin of low electron-hole recombination rate in metal halide perovskites

Alfredo Pasquarello, Francesco Ambrosio, Julia Anna Wiktor

To address the slow recombination of photogenerated charges in tetragonal CH 3 NH 3 PbI 3 , the evolution of extra electrons and holes is simulated through advanced ab initio molecular dynamics. We show that the localization of the charge carriers and thei ...

2018

A hybrid density functional study of lithium in ZnO: Stability, ionization levels, and diffusion

Nava Setter, Alfredo Pasquarello, Alexander Tagantsev, Audrius Alkauskas, Alexandra Sarabando de Carvalho

The properties of interstitial and substitutional Li in wurtzite ZnO are modeled using hybrid density functional calculations. We investigate the impact of the band-gap error on the formation energies of the two defects and their dependence on the Fermi le ...

2009

Fermi-level pinning through defects at GaAs/oxide interfaces: A density functional study

Alfredo Pasquarello, Giacomo Francesco Leonardo Miceli, Davide Colleoni

Using density functional calculations, we study a set of candidate defects for Fermi-level pinning at GaAs/oxide interfaces. The set of considered defects comprises both bulklike and interfacial defects, including As antisites, Ga and As dangling bonds, th ...

American Physical Society2015

Band alignment at beta-Ga2O3/III-N (III = Al, Ga) interfaces through hybrid functional calculations

Alfredo Pasquarello, Sai Lyu

The band alignment and the chemical bonding at the beta -Ga2O3/AlN and beta -Ga2O3/GaN interfaces are studied through hybrid functional calculations. We construct realistic slab models with III-O (III = Al, Ga) bonds dominating the chemical bonding at both ...

2020

Nature of electron trap states under inversion at In0.53Ga0.47As/Al2O3 interfaces

Alfredo Pasquarello, Davide Colleoni

In and Ga impurities substitutional to Al in the oxide layer resulting from diffusion out of the substrate are identified as candidates for electron traps under inversion at In0.53Ga0.47As/Al2O3 interfaces. Through density-functional calculations, these de ...

American Institute of Physics2017

Self-compensation due to point defects in Mg-doped GaN

Alfredo Pasquarello, Giacomo Francesco Leonardo Miceli

Using hybrid density functional theory, we address point defects susceptible to cause charge compensation upon Mg doping of GaN. We determine the free energy of formation of the nitrogen vacancy and of several Mg-related defects. The entropic contribution ...

Amer Physical Soc2016

Band-edge problem in the theoretical determination of defect energy levels: The O vacancy in ZnO as a benchmark case

Alfredo Pasquarello, Audrius Alkauskas

Calculations of formation energies and charge transition levels of defects routinely rely on density functional theory (DFT) for describing the electronic structure. Since bulk band gaps of semiconductors and insulators are not well described in semilocal ...

2011

Small Electron Polarons in CsPbBr3: Competition between Electron Localization and Delocalization

Alfredo Pasquarello, Julia Anna Wiktor, Stefano Falletta

We study the nature of excess electrons in CsPbBr3 and identify several single and double polaronic states. We emphasize the importance of proper inclusion of the self-interaction corrections for the stability of small electron polarons in this material. W ...

AMER CHEMICAL SOC2020

Nonempirical semilocal density functionals for correcting the self-interaction of polaronic states

Alfredo Pasquarello, Stefano Falletta

Through the use of the piecewise-linearity condition of the total energy, we correct the self-interaction for the study of polarons by constructing nonempirical functionals at the semilocal level of theory. We consider two functionals, the gamma DFT and mu ...

Aip Publishing2024

Charge transition levels of nitrogen dangling bonds at Si/SiO2 interfaces: A first-principles study

Alfredo Pasquarello, Peter Broqvist

The defect levels of the nitrogen dangling bond at the Si/SiO2 interface are determined through a density-functional approach. The composition grading at the interface is modeled through crystalline and amorphous models of stoichiometric SiO2, nitrided SiO ...

2010

Assessing the accuracy of hybrid functionals in the determination of defect levels: Application to the As antisite in GaAs

Alfredo Pasquarello, Hannu-Pekka Komsa

The accuracy of nonscreened and screened hybrid functionals for the calculation of defect levels within the band gap is assessed for the As antisite in GaAs, the nature of which is well characterized experimentally. A set of functionals differing by the fr ...

2011

Finite-size corrections of defect energy levels involving ionic polarization

Alfredo Pasquarello, Julia Anna Wiktor, Stefano Falletta

We develop a scheme for finite-size corrections of vertical transition energies and single-particle energy levels involving defect states with built-in ionic polarization in supercell calculations. The method accounts on an equal footing for the screening ...

2020

Range-separated hybrid functionals for accurate prediction of band gaps of extended systems

Alfredo Pasquarello, Stefano Falletta, Jing Yang

In this work, we systematically evaluate the accuracy in band gap prediction of range-separated hybrid functionals on a large set of semiconducting and insulating materials and carry out comparisons with the performance of their global counterparts. We obs ...

NATURE PORTFOLIO2023

Magnetoresistive junctions based on epitaxial graphene and hexagonal boron nitride

Alfredo Pasquarello, Oleg Yazyev

We propose monolayer epitaxial graphene and hexagonal boron nitride (h-BN) as ultimate thickness covalent spacers for magnetoresistive junctions. Using a first-principles approach, we investigate the structural, magnetic, and spin transport properties of s ...

2009

First principles investigation of defect energy levels at semiconductor-oxide interfaces: Oxygen vacancies and hydrogen interstitials in the Si-SiO2-HfO2 stack

Alfredo Pasquarello, Peter Broqvist, Audrius Alkauskas

We introduce a scheme for the calculation of band offsets and defect energy levels at semiconductor-oxide interfaces. Our scheme is based on the use of realistic atomistic models of the interface structure and of hybrid functionals for the evaluation of th ...

American Institute of Physics2009

Interfacial Ga-As suboxide: Structural and electronic properties

Alfredo Pasquarello, Davide Colleoni

The structural and electronic properties of Ga-As suboxide representative of the transition region at the GaAs/oxide interface are studied through density functional calculations. Two amorphous models generated by quenches from the melt are taken under con ...

American Institute of Physics2015