Thickness dependent electronic properties of Pt dichalcogenides

Rovi Angelo B Villaos,Shin-Ming Huang,Christian P Crisostomo,Zhi-Quan Huang,Marvin A Albao,Hsin Lin,Feng-Chuan Chuang,Allan Abraham B Padama

doi:10.1038/s41699-018-0085-z

Abstract

Platinum-based transition metal dichalcogenides have been gaining renewed interest because of the development of a new method to synthesize thin film structures. Here, using first-principles calculation, we explore the electronic properties of PtX2 (X = S, Se, and Te) with respect to film thickness. For bulk and layered structures (1 to 10 layers), octahedral 1T is the most stable. Surprisingly, we also find that the 3R structure has comparable stability relative to the 1T, implying possible synthesis of 3R. For a bulk 1T structure, PtS2 is semiconducting with an indirect band gap of 0.25 eV, while PtSe2 and PtTe2 are both semi-metallic. Still, all their corresponding monolayers exhibit an indirect semiconducting phase with band gaps of 1.68, 1.18, and 0.40 eV for PtS2, PtSe2, and PtTe2, respectively. For the band properties, we observe that all these materials manifest decreasing/closing of indirect band gap with increasing thickness, a consequence of quantum confinement and interlayer interaction. Moreover, we discover that controlling the thickness and applying strain can manipulate van Hove singularity resulting to high density of states at the maximum valence band. Our results exhibit the sensitivity and tunability of electronic properties of PtX2, paving a new path for future potential applications.

Highlights

Transition metal dichalcogenides (TMDs) are very old materials, among which is molybdenite (MoS2), with the earliest sample dating back to more than 2.9 billion years ago.[1]
Layered TMDs generally have the formula MX2, where M corresponds to a transition metal, usually belonging to group IV-VII, and is sandwiched by X atoms which correspond to chalcogens, e.g., S, Se, and Te
In one study,[23] it was observed that the electron mobility at room temperature of PtSe2 is significantly higher than MoS2 implying that it has potential applications in field-effect transistors

Summary

Introduction

Transition metal dichalcogenides (TMDs) are very old materials, among which is molybdenite (MoS2), with the earliest sample dating back to more than 2.9 billion years ago.[1]. It was observed that decreasing the number of layers (L) from bulk to monolayer corresponds to increasing band gap.

Results

Conclusion