Mediator-assisted synthesis of WS2 with ultrahigh-optoelectronic performance at multi-wafer scale

Abstract

The integration of 2D materials into future applications relies on advances in their quality and production. We here report a synthesis method that achieves ultrahigh optoelectronic performance at unprecedented fabrication scales. A mediator-assisted chemical vapor deposition process yields tungsten-disulfide (WS2) with near-unity photoluminescence quantum yield, superior photosensitivity and improved environmental stability. This enhancement is due to the decrease in the density of lattice defects and charge traps brought about by the self-regulating nature of the growth process. This robustness in the presence of precursor variability enables the high-throughput growth in atomically confined stacks and achieves uniform synthesis of single-layer WS2 on dozens of closely packed wafers. Our approach enhances the scientific and commercial potential of 2D materials as demonstrated in producing large-scale arrays of record-breaking optoelectronic devices.

Enhancing optical characteristics of mediator-assisted wafer-scale MoS2 and WS2 on h-BN

“…High-quality and wafer-scale SL mediator-assisted CVD MoS 2 or WS 2 on commercial p-type doping Si substrate capped with 285-300 nm SiO 2 wafer by thermal oxidation methods [43] were successfully grown by 40 nm MoO 3 /WO 3 deposited on graphite paper and 100 SCCM of H 2 S gas as precursors. The growth time is 15 min, and the temperature is 700 °C [35,36]. Such uniformity in the mediator-assisted CVD growth SL MoS 2 and WS 2 films is geared toward producing defect-free multiwafer scale films so as to enhance its crystalline property better than exfoliated 2D material levels [35,36].…”

“…The growth time is 15 min, and the temperature is 700 °C [35,36]. Such uniformity in the mediator-assisted CVD growth SL MoS 2 and WS 2 films is geared toward producing defect-free multiwafer scale films so as to enhance its crystalline property better than exfoliated 2D material levels [35,36]. However, the edges and boundaries of mediator-assisted MoS 2 and WS 2 films could easily be polluted during growing processes and damaged during sample moving processes with tweezers [35,36].…”

“…Such uniformity in the mediator-assisted CVD growth SL MoS 2 and WS 2 films is geared toward producing defect-free multiwafer scale films so as to enhance its crystalline property better than exfoliated 2D material levels [35,36]. However, the edges and boundaries of mediator-assisted MoS 2 and WS 2 films could easily be polluted during growing processes and damaged during sample moving processes with tweezers [35,36]. Therefore, we particularly selected the central region of mediator-assisted wafer-scale MoS 2 and WS 2 in order to avoid worse film quality for further wet transfer process and optical characteristic measurements.…”

“…Here, we used the high-throughput growth with precursor on dozens of closely packed wafers, which is so-called mediator-assisted growing methods to order to grow uniformly the wafer-scale MoS 2 or WS 2 on SiO 2 /Si wafers [35,36]. Furthermore, we successfully performed a wet transfer process to move mediator-assisted MoS 2 or WS 2 on h-BN/SiO 2 /Si heterostructures for optical characteristic measurements.…”

“…Furthermore, we successfully performed a wet transfer process to move mediator-assisted MoS 2 or WS 2 on h-BN/SiO 2 /Si heterostructures for optical characteristic measurements. Recently, our collaborators showed the waferscale mediator-assisted synthesis of MoS 2 or WS 2 on SiO 2 /Si wafer reveals excellent photoluminescence (around 7 times intensity-enhanced) in MoS 2 and near-unity PL quantum yield enhancement in WS 2 due to a reduction of charge trap density in comparison to traditional reactant powder CVD MoS 2 /WS 2 method [35,36]. Such wafer-scale uniform MoS 2 and WS 2 ultrathin film with excellent optoelectronic performances never be investigated on vertical heterostructure h-BN bottom substrates that could reveal better optoelectronic quantum phenomena.…”