Ambient Pressure Chemical Vapor Deposition of Flat and Vertically Aligned MoS2 Nanosheets

Abstract

Molybdenum disulfide (MoS2) got tremendous attention due to its atomically thin body, rich physics, and high carrier mobility. The controlled synthesis of large area and high crystalline monolayer MoS2 nanosheets on diverse substrates remains a challenge for potential practical applications. Synthesizing different structured MoS2 nanosheets with horizontal and vertical orientations with respect to the substrate surface would bring a configurational versatility with benefit for numerous applications, including nanoelectronics, optoelectronics, and energy technologies. Among the proposed methods, ambient pressure chemical vapor deposition (AP-CVD) is a promising way for developing large-scale MoS2 nanosheets because of its high flexibility and facile approach. Here, we show an effective way for synthesizing large-scale horizontally and vertically aligned MoS2 on different substrates such as flat SiO2/Si, pre-patterned SiO2 and conductive substrates (TaN) benefit various direct TMDs production. In particular, we show precise control of CVD optimization for yielding high-quality MoS2 layers by changing growth zone configuration and the process steps. We demonstrated that the influence of configuration variability by local changes of the S to MoO3 precursor positions in the growth zones inside the CVD reactor is a key factor that results in differently oriented MoS2 formation. Finally, we show the layer quality and physical properties of as-grown MoS2 by means of different characterizations: Raman spectroscopy, scanning electron microscopy (SEM), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). These experimental findings provide a strong pathway for conformally recasting AP-CVD grown MoS2 in many different configurations (i.e., substrate variability) or motifs (i.e., vertical or planar alignment) with potential for flexible electronics, optoelectronics, memories to energy storage devices.

Chemical vapor deposition growth of graphene and other nanomaterials with 3D architectures towards electrocatalysis and secondary battery-related applications

“…Currently, this thermodynamic equilibrium growth mode can be disrupted by modulating the growth parameters (e.g., growing at elevated temperature, 56 introducing a seeding promoter 57 ) to grow vertical TMDCs nanosheets on planar substrates. In addition, the kinetic constrains can be improved by precisely controlling the process steps (e.g., accelerating the growth rate, 58 delaying the introduction of excess sulfur source 59 ) to achieve the transition from planar to vertical growth of TMDCs. However, it is still challenging to accurately control the morphology (from horizontal to vertical orientations), thickness, and crystalline quality of the derived TMDCs nanosheets.…”

“…In addition, the kinetic constrains can be improved by precisely controlling the process steps ( e.g. , accelerating the growth rate, 58 delaying the introduction of excess sulfur source 59 ) to achieve the transition from planar to vertical growth of TMDCs. However, it is still challenging to accurately control the morphology (from horizontal to vertical orientations), thickness, and crystalline quality of the derived TMDCs nanosheets.…”

Impact of CVD chemistry on band alignment at the MoS2/SiO2 interface

“…[7] Here we address two different CVD growth methods: (i) the Solid Precursor Film (SPF) approach where pre-deposited thin film of spin-coated ammonium heptamolybdate tetrahydrate (AHM) with sodium hydroxide (NaOH) is sulfurized in a single thermal zone furnace [8] and (ii) the Vapor Phase Reaction (VPR) approach where Mo and S solid powder precursors react in a multiple zones furnace. [9] These two methods were able to produce large area MoS2 with similar thickness. However, a clear understanding of growth chemistry and its influence on the band alignment of MoS2/SiO2 interface in different routes is essential.…”

Template-free scalable growth of vertically-aligned MoS2 nanowire array meta-structural films towards robust superlubricity

“…To date, controlling the basal plane orientation of MoS 2 thin films produced using most methods is still a big challenge. [26][27][28][29][30][31][32][33][34] This severely limits their application in many fields. Therefore, developing a template-free atomic layer orientation controllable growth approach is of central importance.…”