Synthesis and Transfer of Large-Area Monolayer WS₂Crystals: Moving Toward the Recyclable Use of Sapphire Substrates

Abstract

Two-dimensional layered transition metal dichalcogenides (TMDs) show intriguing potential for optoelectronic devices due to their exotic electronic and optical properties. Only a few efforts have been dedicated to large-area growth of TMDs. Practical applications will require improving the efficiency and reducing the cost of production, through (1) new growth methods to produce large size TMD monolayer with less-stringent conditions, and (2) nondestructive transfer techniques that enable multiple reuse of growth substrate. In this work, we report to employ atmospheric pressure chemical vapor deposition (APCVD) for the synthesis of large size (>100 μm) single crystals of atomically thin tungsten disulfide (WS2), a member of TMD family, on sapphire substrate. More importantly, we demonstrate a polystyrene (PS) mediated delamination process via capillary force in water which reduces the etching time in base solution and imposes only minor damage to the sapphire substrate. The transferred WS2 flakes are of excellent continuity and exhibit comparable electron mobility after several growth cycles on the reused sapphire substrate. Interestingly, the photoluminescence emission from WS2 grown on the recycled sapphire is much higher than that on fresh sapphire, possibly due to p-type doping of monolayer WS2 flakes by a thin layer of water intercalated at the atomic steps of the recycled sapphire substrate. The growth and transfer techniques described here are expected to be applicable to other atomically thin TMD materials.

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

“…CVD‐grown graphene has made great breakthrough in the growth of large‐area graphene 17, 155, 156, 157, 158, 159, 160. Recently, the synthesis of 2DLMs via CVD methods has been illustrated in many reports especially for MoS 2 ,30, 31, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185 which also shows promising applications in electronics and optoelectronics. Up to now, there are several reports on synthesizing 2D GIVMCs nanoflakes via CVD method, which is still at the initial stage.…”

MoS2/WS2 Quantum Dots as High‐Performance Lubricant Additive in Polyalkylene Glycol for Steel/Steel Contact at Elevated Temperature

“…As shown in the set of Figure 1D,H, the calculated lattice spacings of MoS 2 and WS 2 QDs are 0.23 and 0.27 nm, which can be indexed to the (103) planes of MoS 2 crystals, and (101) planes of WS 2 crystals, respectively. [20,23] To identify the chemical composition of MoS 2 /WS 2 QDs, XPS was used to measure the binding energy of Mo, W, and S. Figure 2A,B shows the binding energy of Mo 3d and S 2p. Three peaks at 227.0, 229.6, and 232.8 are attributed to the 2s electrons of S 2− , Mo 4+ 3d 5/2 , and Mo 4+ 3d 3/2 , respectively.…”

Recent progress on liquid metals and their applications

“…There are many methods to fabricate 2D materials, such as the exfoliation technique, atomic layer deposition [75] and chemical vapour deposition [76,77], but finding a method to make high-quality, large-area and large-scale 2D sheets remains a great challenge. Carey et al introduced an approach to transform the native surface metal oxide layer of low melting point metal precursors to fabricate 2D metal chalcogenide compounds [70].…”