Thickness modulated MoS2 grown by chemical vapor deposition for transparent and flexible electronic devices

Abstract

Two-dimensional (2D) materials have been a great interest as high-performance transparent and flexible electronics due to their high crystallinity in atomic thickness and their potential for variety applications in electronics and optoelectronics. The present study explored the wafer scale production of MoS 2 nanosheets with layer thickness modulation from single to multi-layer by using two-step method of metal deposition and CVD process. The formation of high-quality and layer thickness-modulated MoS 2 film was confirmed by Raman spectroscopy, AFM, HRTEM, and photoluminescence analysis. The layer thickness was identified by employing a simple method of optical contrast value. The image contrast in green (G) channel shows the best fit as contrast increases with layer thickness, which can be utilized in identifying the layer thickness of MoS 2. The presence of critical thickness of Mo for complete sulphurization, which is due to the diffusion limit of MoS 2 transformation, changes the linearity of structural, electrical, and optical properties of MoS 2. High optical transparency of >90%, electrical mobility of $12.24 cm 2 V À1 s À1 , and I on/off of $10 6 characterized within the critical thickness make the MoS 2 film suitable for transparent and flexible electronics as compared to conventional amorphous silicon (a-Si) or organic films. The layer thickness modulated large scale MoS 2 growth method in conjunction with the layer thickness identification by the nondestructive optical contrast will definitely trigger development of scalable 2D MoS 2 films for transparent and flexible electronics.

Radiation-induced direct bandgap transition in few-layer MoS2

“…The thickness of the flakes is determined from the contrast in the optical microscopy images and the energy of the indirect band emission peak in the PL spectra. 19,20 Scanning electron microscopy (SEM) images were taken after all optical characterization, in order to avoid contamination and potential quenching of the MoS 2 photoluminescence. Figure 1 shows optical microscopy and SEM images of one of the flakes investigated in this study.…”

Chemical vapor deposition synthesis of two-dimensional freestanding transition metal oxychloride for electronic applications

“…Furthermore, we can obtain the VOCl flakes with various thicknesses, ranging from 1.5 nm to 57 nm. Interestingly, the thick samples with large area of around 10 µm × 40 µm can also be obtained in the experiment ( Figure S2), which has been challenging in the synthesis of TMDCs and other 2D materials [38,39]. It should be emphasized that this transfer approach is contamination-free and damage-free, which would be of crucial importance in fabricating high-yield and high-performance electronic and optoelectronic devices.…”

Hybridizing Plasmonic Materials with 2D‐Transition Metal Dichalcogenides toward Functional Applications

“…Another easy technique of growing large‐scale 2D‐TMDs is the “two‐step method.” A transition metal thin film (e.g., Mo, W, and Nb) is deposited on a substrate followed by the thermal reaction with a chalcogen (e.g., S, Se, and Te) vapor in an inert atmosphere at high temperatures of 300–700 °C. This approach has been demonstrated in Figure 10b, where the metals (Mo, W) were coated with controlled thicknesses on substrates and placed in a CVD furnace to react with sulfur powder in an inert environment125 as described below …”