Rapid wafer-scale fabrication with layer-by-layer thickness control of atomically thin MoS2 films using gas-phase chemical vapor deposition

Abstract

Design and development of the growth-process for the production of wafer-scale spatially homogeneous thickness controlled atomically thin transition metal dichalcogenides (TMDs) is one of the key challenges to realize modern electronic devices. Here, we demonstrate rapid and scalable synthesis of MoS2 films with precise thickness control via gas-phase chemical vapor deposition approach. We show that a monolayer MoS2 can be synthesized over a 2-in. sapphire wafer in a growth time as low as 4 min. With a linear growth rate of 1-layer per 4 min, MoS2 films with thicknesses varying from 1- to 5-layers with monolayer precision are produced. We propose that, in addition to Raman spectroscopy, the energy splitting of exciton bands in optical-absorbance spectra may be another choice for layer thickness identification. With suitable precursor selection, our approach can facilitate the rapid synthesis of spatially homogeneous atomically thin TMDs on a large scale.

Spatially isolated neutral excitons via clusters on trilayer MoS2

“…Through the main Raman peak difference between the E 2g 1 and A 1g modes in our MoS 2 sample (inset in Fig. 1f ), the change of thickness was confirmed from 3L to 5L in the near edge, 18 which corresponds to the AFM data in Fig. S3.…”

Barrier-assisted vapor phase CVD of large-area MoS2 monolayers with high spatial homogeneity

“…Alternatively, chemical vapor deposition (CVD) is proven to be a suitable method to grow single crystal MoS 2 with layer controllability and homogeneity over large area. [12][13][14] Based on the type of precursor used, CVD reactions can be classied as gas phase and vapor phase, and most of the current CVD based MoS 2 production uses either of these two methods. In the gas phase CVD approach, pyrolysis of Mo based hexacarbonyl or organometallic compounds and hydrogen sulphide (H 2 S) occurs on the substrate in a reaction chamber, resulting in continuous MoS 2 on a wafer scale with atomically smooth surfaces.…”

“…In the gas phase CVD approach, pyrolysis of Mo based hexacarbonyl or organometallic compounds and hydrogen sulphide (H 2 S) occurs on the substrate in a reaction chamber, resulting in continuous MoS 2 on a wafer scale with atomically smooth surfaces. [14][15][16][17] Though this method is considered promising for the growth of wafer-scale MoS 2 , the high price of the Mo precursors and the need for safety systems to handle certain toxic precursors make this method costly and environmentally not benign. Alternatively, the use of solid phase precursors such as molybdenum trioxide (MoO 3 ) and sulfur to grow MoS 2 lms has attracted signicant attention as these precursors are environmentally friendly and the growth setup is simple and relatively low cost.…”

MoS2 Thin Films Grown by Sulfurization of DC Sputtered Mo Thin Films on Si/SiO2 and C-Plane Sapphire Substrates

“…13a were attributed to the excitonic transitions at the K point of the Brillouin zone in bulk MoS 2 which are the direct-gap transitions between the maxima of split valance bands and the minimum of the conduction band. 1,29,48,49 Figure 13b and c depicts the plots of the a and (ahm) 1/2 vs. hm of the films. The absorption coefficients of the films were calculated using the following relation:…”