Synthesis of vertically aligned wafer-scale tantalum disulfide using high-Ar/H₂S ratio plasma

Abstract

Nanostructural modification of two-dimensional (2D) materials has attracted significant attention for enhancing hydrogen evolution reaction (HER) activity. In this study, the nanostructure of TaS2 films was controlled by controlling the Ar/H2S gas ratio used in plasma-enhanced chemical vapor deposition (PECVD). At a high Ar/H2S gas ratio, vertically aligned TaS2 (V-TaS2) films were formed over a large-area (4 in) at a temperature of 250 °C, which, to the best of our knowledge, is the lowest temperature reported for PECVD. Furthermore, the plasma species formed in the injected gas at various Ar/H2S gas ratios were analyzed using optical emission spectroscopy to determine the synthesis mechanism. In addition, the 4 in wafer-scale V-TaS2 was analyzed by x-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy, and the HER performance of the as-synthesized TaS2 fabricated with various Ar/H2S ratios was measured. The results revealed that, depending on the film structure of TaS2, the HER performance can be enhanced owing to its structural advantage. Furthermore, the excellent stability and robustness of V-TaS2 was confirmed by conducting 1000 HER cycles and post-HER material characterization. This study provides important insights into the plasma-assisted nanostructural modification of 2D materials for application as enhanced electrocatalysts.

Plasma Processing and Treatment of 2D Transition Metal Dichalcogenides: Tuning Properties and Defect Engineering

“…The PECVD method is also capable of synthesizing vertically aligned TMD layers at low temperatures (300 °C). This vertical alignment is obtained by depositing a metal layer on the substrate prior to the PECVD process and using Ar:H 2 X (X: chalcogen) as plasma gas. , The impact of gas flow on the morphology of vertically aligned TaS 2 layers was studied by Seok et al . Remarkably, the authors state that pure H 2 S is incapable of transforming Ta films to TaS 2 , while increasing the Ar:H 2 S ratio to 15:15 resulting in the formation of a few incomplete lateral and amorphous TaS 2 films.…”

Beyond von Neumann Architecture: Brain‐Inspired Artificial Neuromorphic Devices and Integrated Computing

“…Material candidates with unique properties, such as TMD, metal oxides, organic materials, halide perovskite, graphene, h-BN, and BP, are discussed for various neuromorphic devices and computing. To realize advanced neuromorphic devices, certain issues, such as material engineering [18] for sufficient filament generation or low-temperature synthesis [19] for flexible devices, should be further explored. The construction of low-power, high-density, and heterogeneous neuromorphic systems has become increasingly promising, thereby paving new pathways for future computing architectures.…”

Tailoring Polymorphic Heterostructures of MoS2–WS2 (1T/1T, 2H/2H) for Efficient Hydrogen Evolution Reaction

“…7 In particular, cold-plasma-assisted 2D TMDCs have been investigated to develop applications for hydrogen evolution reaction (HER) electrocatalysts for achieving renewable energy because of their intrinsic catalytic activity, earth abundance, and low cost. 8,9 Further understanding of the factors that affect catalytic activity can enhance the HER performance. 10 For example, defective structures (e.g., sulfur (S) vacancies and edge sites) can decrease the H 2 adsorption free energy (ΔG H ), resulting in enhanced H 2 adsorption, as indicated in theoretical and experimental results.…”

“…Two-dimensional (2D) transition metal dichalcogenide (TMDC)-based nanomaterials have garnered considerable attention because of their unique chemical, physical, and electrical properties. , Their high activation energy for grain growth in the cold plasma process makes them highly suited for 2D materials as their bulk growth is constrained compared with that in the calcination process, which requires low activation energy . In particular, cold-plasma-assisted 2D TMDCs have been investigated to develop applications for hydrogen evolution reaction (HER) electrocatalysts for achieving renewable energy because of their intrinsic catalytic activity, earth abundance, and low cost. , Further understanding of the factors that affect catalytic activity can enhance the HER performance . For example, defective structures (e.g., sulfur (S) vacancies and edge sites) can decrease the H 2 adsorption free energy (Δ G H ), resulting in enhanced H 2 adsorption, as indicated in theoretical and experimental results .…”