# Structural modification of thin Bi(1 1 1) films by passivation and native oxide model

## TL;DR

This study uses first-principles calculations to explore how passivation and native oxide layers influence the structure and orientation of thin Bi(111) films, with implications for nanoelectronic applications.

## Contribution

It introduces a simple model for native oxide layers that preserve film orientation, enhancing understanding of surface modifications in ultrathin bismuth films.

## Key findings

- Covalent bonds can reorient ultrathin Bi(111) films.
- Native oxide layers stabilize film orientation.
- Surface effects diminish with increasing film thickness.

## Abstract

The structure of thin terminated Bi(1 1 1) films of approximately 1 nm thickness is investigated from first principles. Our density functional theory calculations show that covalent bonds to the surface can change the orientation of the films completely. For thicker films, the effect is limited to the surface only. Based on these observations, we further present a simple model structure for the native oxide and chemically similar oxides, which form a protective capping layer, leaving the orientation of the films unchanged. The advantages of this energetically favorable layered termination are discussed in the context of the films' technological exploitation in nanoelectronic devices.