Uncovering the atomic structure of substitutional platinum dopants in MoS$_2$ with single-sideband ptychography

TL;DR

This paper demonstrates that single-sideband ptychography can accurately identify atomic structures of platinum dopants in monolayer MoS$_2$, surpassing traditional imaging methods in sensitivity and damage reduction.

Contribution

It introduces the application of SSB ptychography for detailed atomic analysis of doped 2D materials, providing enhanced contrast and lower electron dose requirements.

Findings

SSB ptychography reliably identifies Pt dopant structures.

Compared to HAADF STEM, SSB offers higher phase sensitivity and lower damage.

The method enables detailed atomic mapping of dopants in MoS$_2$.

Abstract

We substitute individual Pt atoms into monolayer MoS$_2$ and study the resulting atomic structures with single-sideband (SSB) ptychography supported by ab initio simulations. We demonstrate that while high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) imaging provides excellent Z-contrast, distinguishing some defect types such as single and double sulfur vacancies remains challenging due to their low relative contrast difference. However, SSB with its nearly linear Z-contrast and high phase sensitivity enables reliable identification of these defect configurations as well as various Pt dopant structures at significantly lower electron doses. Our findings uncover the precise atomic placement and highlight the potential of SSB ptychography for detailed structural analysis of dopant-modified 2D materials while minimizing beam-induced damage, offering new pathways for understanding and engineering atomic-scale features in 2D systems.