Synthesis of Wafer-Scale Monolayer WS₂ Crystals toward the Application in Integrated Electronic Devices

Abstract

Two-dimensional transition-metal dichalcogenides (TMDCs) possess unique electronic and optical properties, which open up a new opportunity for atomically thin optoelectronic devices. Synthesizing large-scale monolayer TMDCs on the SiO 2 /Si substrate is crucial for practical applications, however, it remains a big challenge. In this work, a method which combines chemical vapor deposition (CVD) and thermal evaporation was employed to grow monolayer tungsten disulfide (WS 2 ) crystals. Through controlling the density and the distribution of W precursors, a wafer-scale continuous uniform WS 2 film was achieved, with the structural and spectral characterizations confirming a monolayer configuration and a high crystalline quality. Wafer-scale field-effect transistor arrays based on the monolayer WS 2 were fabricated. The devices show superior electrical performances, and the maximal mobility is almost 1 order of magnitude higher than those of CVD-grown large-scale TMDC devices reported so far.

Epitaxial Single‐Crystal Growth of Transition Metal Dichalcogenide Monolayers via the Atomic Sawtooth Au Surface

“…h) Benchmark of carrier concentrations and i) field‐effect mobility and on/off ratio of SC WS 2 FETs with those values from the literature. [ 29–38 ]…”

“…[29][30][31][32][33] Moreover, the FET devices in terms of field-effect mobilities (≈3 cm 2 V -1 s -1 ) and on/off ratios (≈10 8 ) outperform previously reported values of CVD-derived polycrystalline monolayer WS 2 FETs. [29][30][31][32][33][34][35][36][37][38] More notably, such performances are comparable to those of SC monolayer WS 2 FETs. These indicate that SC WS 2 film has remarkable crystallinity over the whole region (Figure 3i).…”

“…h) Benchmark of carrier concentrations and i) field-effect mobility and on/off ratio of SC WS 2 FETs with those values from the literature. [29][30][31][32][33][34][35][36][37][38] edge over other angles independent of Miller indices (Figure 4c; Table S3, Supporting Information). Another metastable angle is found at 60° with a rotational barrier height of 0.25-0.75 eV, which varies with Miller indices.…”

“…g) Representative I-V transfer curve obtained from SC WS 2 FET. h) Benchmark of carrier concentrations and i) field-effect mobility and on/off ratio of SC WS 2 FETs with those values from the literature [29][30][31][32][33][34][35][36][37][38].…”

Avalanche photodetectors based on two-dimensional layered materials

“…2D monolayer TMDs such as MoS2, WS2, and WSe2 etc., could in principle be synthesized in large-scale using chemical vapor deposition (CVD) method [83][84][85]. Monolayer MoS2 has a direct bandgap making it interesting for applications in optoelectronics such as light-emitting diodes and photodetectors [86].…”