Publications de Davide Colleoni

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

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

Oxygen defects in GaAs: A hybrid functional study

Alfredo Pasquarello, Davide Colleoni

Using hybrid density functional calculations, we address the structural properties, formation energies, and charge transition levels of a variety of oxygen defects in GaAs. The set of considered defects comprises the bridging O atom in a As-O-Ga configurat ...

Amer Physical Soc2016

Diffusion of interstitial oxygen in silicon and germanium: A hybrid functional study

Alfredo Pasquarello, Davide Colleoni

The minimum-energy paths for the diffusion of an interstitial O atom in silicon and germanium are studied through the nudged-elastic-band method and hybrid functional calculations. The reconsideration of the diffusion of O in silicon primarily serves the p ...

2016

Band alignment and chemical bonding at the GaAs/Al2O3 interface: A hybrid functional study

Alfredo Pasquarello, Davide Colleoni, Giacomo Francesco Leonardo Miceli

The band alignment at the interface between GaAs and amorphous Al2O3 is studied through the use of hybrid functionals. For the oxide component, a disordered model is generated through density-functional molecular dynamics. The achieved structure shows good ...

2015

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

Alfredo Pasquarello, Davide Colleoni, Giacomo Francesco Leonardo Miceli

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

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

Origin of Fermi-level pinning at GaAs/oxide interfaces through the hybrid functional study of defects

Davide Colleoni

Gallium arsenide is currently under scrutiny for replacing silicon in microelectronic devices due to its high carrier mobilities. However, the widespread use of this semiconductor is hampered by the intrinsic difficulty of producing high-quality interfaces ...

EPFL2015

Arsenic related defect states resonant with the semiconductor conduction band at the In0.53Ga0.47As/oxide interface: A density functional study

Alfredo Pasquarello, Davide Colleoni, Giacomo Francesco Leonardo Miceli

An arsenic related defect at the In0.53Ga0.47As/oxide interface is studied through density functional theory. This defect corresponds to an As-As timer which transforms into two doubly occupied As dangling bonds upon capture of two electrons. The defect ch ...

Elsevier2015

Origin of Fermi-level pinning at GaAs surfaces and interfaces

Alfredo Pasquarello, Davide Colleoni, Giacomo Francesco Leonardo Miceli

Through first-principles simulation methods, we assign the origin of Fermi-level pinning at GaAs surfaces and interfaces to the bistability between the As-As dimer and two As dangling bonds, which transform into each other upon charge trapping. This defect ...

Institute of Physics2014

The O-As defect in GaAs: A hybrid density functional study

Alfredo Pasquarello, Davide Colleoni

The O center substitutional to As (O-As) is addressed through hybrid functional calculations as a candidate defect to explain the Fermi-level pinning in oxygen-doped GaAs. The defect center shows amphoteric behavior which could lead to Fermi-level pinning. ...

Elsevier2014

Assignment of Fermi-level pinning and optical transitions to the (As-Ga)(2)-O-As center in oxygen-doped GaAs

Alfredo Pasquarello, Davide Colleoni

The (As-Ga)(2)-O-As defect in oxygen-doped GaAs, consisting of two As antisites neighboring an O center substitutional to As, is addressed through hybrid functional calculations. This defect not only accounts for the nearest neighbor environment of the O a ...

2013

Amphoteric defects in GaAs leading to Fermi-level pinning: A hybrid functional study

Alfredo Pasquarello, Davide Colleoni

Formation energies and charge transition levels of amphoteric defects in GaAs giving rise to Fermi-level pinning are calculated with hybrid functionals. The hybrid functional results indicate that previously identified defects involving the bistable nature ...

Elsevier2013