# Local geometry around B atoms in B/Si(111) from polarized x-ray absorption spectroscopy

## TL;DR

This study uses polarized x-ray absorption spectroscopy to determine the local geometry of boron atoms in a doped silicon surface, revealing their subsurface and surface positions depending on preparation methods.

## Contribution

It provides detailed insights into the atomic positions of boron in doped silicon using polarized NEXAFS and ab-initio calculations, highlighting the variability based on preparation.

## Key findings

- Most B atoms are in subsurface L$_{1}^{c}$ positions beneath Si atoms.
- Some B atoms are located at the surface near Si atoms.
- Preparation method influences B atom locations.

## Abstract

The arrangement of B~atoms in a doped Si(111)-$(\sqrt{3}\times\sqrt{3})R30^{\circ}$:B system was studied using near-edge x-ray absorption fine structure (NEXAFS). Boron atoms were deposited via segregation from the bulk by flashing the sample repeatedly. The positions of B~atoms are determined by comparing measured polarized (angle-dependent) NEXAFS spectra with spectra calculated for various structural models based on ab-initio total energy calculations. It is found that most of boron atoms are located in sub-surface L$_{1}^{c}$ positions, beneath a Si atom. However, depending on the preparation method a significant portion of B~atoms may be located elsewhere. A possible location of these non-L$_{1}^{c}$-atoms is at the surface, next to those Si atoms which form the $(\sqrt{3}\times\sqrt{3})R30^{\circ}$ reconstruction.

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Source: https://tomesphere.com/paper/1902.06244