The rise and fall of an oxide: insights into the phase diagram of bismuth oxide on Au(111)

TL;DR

This study provides a detailed structural and electronic analysis of bismuth oxide thin films on Au(111), revealing phase evolution, surface reconstructions, and potential for device integration with 2D semiconductors.

Contribution

It offers the first comprehensive multi-technique investigation of Bi$_2$O$_3$ on Au(111), including structural models and electronic interface modifications.

Findings

Bi deposition induces surface reconstructions.

Oxidation leads to complex Bi$_2$O$_3$ domain formation.

Structural model consistent with $eta$-Bi$_2$O$_3$ $(201)$ surface.

Abstract

Bismuth oxide (Bi$_2$O$_3$) is a polymorphic material of considerable technological interest, with applications spanning from heterogeneous catalysis to next-generation nanoelectronics. Despite its relevance, systematic investigations of Bi$_2$O$_3$ thin films remain scarce. Here, we report a comprehensive, multi-technique study of bismuth oxide grown on Au(111). By combining synchrotron-based x-ray photoelectron spectroscopy and diffraction with low-energy electron diffraction and scanning tunneling microscopy, we elucidate the structural evolution of the surface during controlled oxidation and subsequent annealing. We find that Bi deposition induces well-defined surface reconstructions, whereas oxidation triggers the formation of a complex sequence of Bi$_2$O$_3$ domains. High-resolution spectroscopic and diffraction data enable us to propose a structural model consistent with the $(201)$ surface of $\beta$-Bi$_2$O$_3$. In addition, work function measurements reveal substantial electronic modifications at the interface. These results provide benchmark structural and electronic insights into the Bi oxide/Au(111) system and establish a framework for integrating Bi$_2$O$_3$ in devices in combination to two-dimensional semiconductors exploiting its low contact resistance.