Publication

Hydrogen in Si(100)-SiO2-HfO2 gate stacks: Relevant charge states and their location

Alfredo Pasquarello
2007
Journal Articles

Abstract

Using a density functional approach, we study the energetics of various charged hydrogen states in the Si(100)-SiO2-HfO2 gate stack. We describe the SiO2-HfO2 transition region through model structures of amorphous hafnium silicate HfxSi1-xO2 with different Hf contents x. Hydrogen is found to be amphoteric with a +/- charge transition level lying close to the Si conduction band minimum. This implies that protons are the most stable form of hydrogen for most electron chemical potentials in the Si band gap. Formation energies of the positively charged state across the Si(100)-SiO2-HfO2 stack indicate that protons mainly locate in the Si-SiO2 or SiO2-HfO2 transition regions. (c) 2007 American Institute of Physics.

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https://infoscience.epfl.ch/entities/publication/6ee2298c-08d3-4a04-9a7a-bce2b589b60e

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Alfredo Pasquarello
2007
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/6ee2298c-08d3-4a04-9a7a-bce2b589b60e

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.

Direct and indirect band gaps

In semiconductor physics, the band gap of a semiconductor can be of two basic types, a direct band gap or an indirect band gap. The minimal-energy state in the conduction band and the maximal-energy state in the valence band are each characterized by a certain crystal momentum (k-vector) in the Brillouin zone. If the k-vectors are different, the material has an "indirect gap". The band gap is called "direct" if the crystal momentum of electrons and holes is the same in both the conduction band and the valence band; an electron can directly emit a photon.

Electronic band structure

In solid-state physics, the electronic band structure (or simply band structure) of a solid describes the range of energy levels that electrons may have within it, as well as the ranges of energy that they may not have (called band gaps or forbidden bands). Band theory derives these bands and band gaps by examining the allowed quantum mechanical wave functions for an electron in a large, periodic lattice of atoms or molecules.

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