Publication

Charge state of the O-2 molecule during silicon oxidation through hybrid functional calculations

Alfredo Pasquarello
2008
Journal Articles

Abstract

We study the charge state of the diffusing O-2 molecule during silicon oxidation through hybrid functional calculations. We calculate charge-transition levels of O-2 in bulk SiO2 and use theoretical band offsets to align these levels with respect to the Si band edges. To overcome the band-gap problem of semilocal density functionals, we employ hybrid functionals with both predefined and empirically adjusted mixing coefficients. We find that the charge-transition level epsilon(0/-) in bulk SiO2 occurs at similar to 1.1 eV above the silicon conduction-band edge, implying that the O-2 molecule diffuses through the oxide in the neutral charge state. While interfacial effects concur to lower the charge-transition level, our estimates suggest that the neutral charge state persists until silicon oxidation.

Official source

https://infoscience.epfl.ch/entities/publication/cb9b6f03-1145-4c87-a4fb-f0fb61379a2d

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Alfredo Pasquarello
2008
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/cb9b6f03-1145-4c87-a4fb-f0fb61379a2d

About this result

Related concepts (32)

Band gap

In solid-state physics and solid-state chemistry, a band gap, also called a bandgap or energy gap, is an energy range in a solid where no electronic states exist. In graphs of the electronic band structure of solids, the band gap refers to the energy difference (often expressed in electronvolts) between the top of the valence band and the bottom of the conduction band in insulators and semiconductors. It is the energy required to promote an electron from the valence band to the conduction band.

Energy level

A quantum mechanical system or particle that is bound—that is, confined spatially—can only take on certain discrete values of energy, called energy levels. This contrasts with classical particles, which can have any amount of energy. The term is commonly used for the energy levels of the electrons in atoms, ions, or molecules, which are bound by the electric field of the nucleus, but can also refer to energy levels of nuclei or vibrational or rotational energy levels in molecules.

Silicon

Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive. Because of its high chemical affinity for oxygen, it was not until 1823 that Jöns Jakob Berzelius was first able to prepare it and characterize it in pure form.

Related publications (1)

Charge state of the O-2 molecule during silicon oxidation through hybrid functional calculations

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