Selenium / Tellurium Two-Dimensional Structures: from Isovalent Se Dopants in Te to Atomically Thin Se Films

TL;DR

This study explores how selenium doping modifies the structural and electronic properties of 2D tellurium films, revealing new doping mechanisms and structural phases that enhance their potential for electronic applications.

Contribution

It demonstrates the controlled isovalent doping of 2D tellurium with selenium and the formation of distinct Se structures, advancing understanding of tuning 2D elemental semiconductors.

Findings

Se atoms replace surface Te atoms, enabling efficient electron doping.

Two types of Se structures, trigonal Se and Se8, are formed on Te films.

Se doping lowers the work function of Te films.

Abstract

Two-dimensional (2D) elemental semiconductors have great potential for device applications, but their performance is limited by the lack of efficient doping methods. Here, combining molecular beam epitaxy, scanning tunneling microscopy/spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations, we investigate the evolution of the structural and electronic properties of 2D selenium/tellurium films with increased Se dosages on graphene/6H-SiC(0001) substrates. We found that Se atoms form isovalent dopants by replacing surface Te atoms, which introduces efficient electron doping and lowers the work function of Te films. With the Se dosage increasing, two types of elemental 2D crystalline Se structures, trigonal Se and Se8 molecular assembly films, are obtained on ultrathin Te films, which are distinct from the amorphous Se acquired by depositing Se directly on graphene/6H-SiC(0001). Our results shed light on tuning the electronic properties of 2D elemental semiconductors by isovalent doping and constructing heterostructures of isovalent 2D elemental materials.