Toward the use of CVD-grown MoS₂ nanosheets as field-emission source

Abstract

Densely populated edge-terminated vertically aligned two-dimensional MoS2 nanosheets (NSs) with thicknesses ranging from 5 to 20 nm were directly synthesized on Mo films deposited on SiO2 by sulfurization. The quality of the obtained NSs was analyzed by scanning electron and transmission electron microscopy, and Raman and X-ray photoelectron spectroscopy. The as-grown NSs were then successfully transferred to the substrates using a wet chemical etching method. The transferred NSs sample showed excellent field-emission properties. A low turn-on field of 3.1 V/μm at a current density of 10 µA/cm2 was measured. The low turn-on field is attributed to the morphology of the NSs exhibiting vertically aligned sheets of MoS2 with sharp and exposed edges. Our findings show that the fabricated MoS2 NSs could have a great potential as robust high-performance electron-emitter material for various applications such as microelectronics and nanoelectronics, flat-panel displays and electron-microscopy emitter tips.

Recent Progress in the Synthesis of MoS2 Thin Films for Sensing, Photovoltaic and Plasmonic Applications: A Review

“…Chemical vapor deposition (CVD) is one of the most popular routes for large-scale, high-quality, and low-cost 2D-MoS 2 material production [49,[67][68][69]. CVD is a bottomup fabrication method at the equilibrium state, which enables the processing of layered 2D-MoS 2 with controlled morphology and good crystallinity while minimizing structural defects.…”

“…A similar process could be used to grow 2D-MoS 2 layers [36,70] by employing two sources, such as molybdenum thin film (below 20 nm) or molybdenum oxide (MoO 3 ) powder deposited on a SiO 2 /Si substrate as a first precursor and the sulfur powder or gaseous sulfur source (H 2 S, etc.) as the second precursor [49,[67][68][69]71,72]. A typical CVD sulfurization process (Figure 2a) is usually performed in a tubular furnace reactor, where a continuous argon flow (typical flow rate 100 sccm) is used as a carrier gas to stream the evaporated sulfur into the Mo source materials.…”

“…This variety of forms could be controlled by choosing suitable synthesis routes with optimized operating parameters [38][39][40][41][43][44][45][46][47]. Thus, it is possible to adjust the 2D-MoS 2 properties to develop high performance devices i energy storage [47], electronics [46], photonics [45], sensing [48], and field emission [49] applications. Recently, up to few-layer MoS 2 nanosheets have been shown to be highly efficient for electronic, optoelectronic, and solar energy harvesting devices [50][51][52] because of their tunable direct bandgap [53], strong light-absorption, and prominent photoluminescence with energies lying in the visible range (1.8-1.9 eV) [54].…”

Layered MoS2 Nanosheets Fabricated by Vacuum Electron Beam Evaporation and Thickness‐Dependent Field Emission Properties

“…[10][11][12][13][14] MoS 2 has rendered a broad potential application in hydrogen evolution reaction, lithium batteries, sensors, FE devices, and other optoelectronic devices. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] MoS 2 is a typical 2D material and belongs to the transition metal dichalcogenide (TMD) family. In 2D MoS 2 , the Mo atoms are sandwiched between two layers of S atoms, which are characterized by a strong covalent bond interaction within the layer and weak van der Waals interaction between the two layers.…”

“…Especially in recent years, MoS 2 has attracted much attention because of its large specific surface area, large electrical conductivity, high chemical stability, high mechanical property, and so on . MoS 2 has rendered a broad potential application in hydrogen evolution reaction, lithium batteries, sensors, FE devices, and other optoelectronic devices …”