High yield synthesis and liquid exfoliation of two-dimensional belt like hafnium disulphide

TL;DR

This paper presents a simple, cost-effective method for synthesizing and exfoliating high-yield, stable monolayer and few-layer hafnium disulphide nanosheets with promising electronic properties for device applications.

Contribution

It introduces a novel scalable synthesis and exfoliation technique for HfS2 with large interlayer spacing, enabling high-yield production of stable nanosheets for electronic use.

Findings

Exfoliated HfS2 nanosheets have an indirect bandgap of 1.3 eV.

The nanosheets exhibit high ambient stability.

Field-effect transistors show mobility of 0.95 cm²/V·s and Ion/Ioff ratio of 10^4.

Abstract

Producing monolayers and few-layers in high yield with environment-stability is still a challenge in hafnium disulphide (HfS2), which is a layered two-dimensional material of group-IV transition metal dichalcogenides, to reveal its unlocked electronic and optoelectronic applications. For the first time, to the best of our knowledge, we demonstrate a simple and cost-effective method to grow layered belt-like nano-crystals of HfS2 with surprisingly large interlayer spacing followed by its chemical exfoliation. Various microscopic and spectroscopic techniques reveal these as-grown crystals exfoliate into single or few layers in some minutes using solvent assisted ultrasonification method in N-Cyclohexyl-2-pyrrolidone. The exfoliated nanosheets of HfS2 exhibit an indirect bandgap of 1.3 eV with high stability against ambient degradation. Further, we demonstrate that these nanosheets holds potential for electronic applications by fabricating field-effect transistors based on few layered HfS2 exhibiting field-effect mobility of 0.95 cm2/V-s with a high current modulation ratio (Ion/Ioff) of 10^4 in ambient. The method is scalable and has potential significance for both academy and industry.