Tuning the Work Function of Si(100) Surface by Halogen Absorption: A DFT Study

TL;DR

This study uses first-principles calculations to show that halogen atoms on Si(100) surfaces increase the work function, with effects influenced by electronegativity and charge redistribution, regardless of surface orientation.

Contribution

It provides a systematic analysis of how halogen chemisorption modifies the work function of Si(100), highlighting the dominant role of chemical species over surface orientation.

Findings

Halogen atoms increase the Si(100) work function compared to hydrogenation.

Electronegativity and charge redistribution are key factors in work function tuning.

Surface orientation has less impact than chemisorbed species on electronic properties.

Abstract

First-principles calculations of work function tuning induced by different chemical terminations on Si(100) surface are presented and discussed. We find that the presence of halogen atoms (I, Br, Cl, and F) leads to an increase of the work function if compared to the fully hydrogenated surface. This is a quite general effect and is directly linked to the chemisorbed atoms electronegativity as well as to the charge redistribution at the interface. All these results are examined with respect to previous theoretical works and experimental data obtained for the (100) as well as other Si surface orientations. Based on this analysis, we argue that the changes in the electronic properties caused by variations of the interfacial chemistry strongly depend on the chemisorbed species and much less on the surface crystal orientation.