Pulsed Carrier Gas Assisted High-Quality Synthetic 3R-Phase Sword-like MoS2: A Versatile Optoelectronic Material

Le résumé fourni par la source

Synthesizing a material with the desired polymorphic phase in a chemical vapor deposition (CVD) process requires a delicate balance among various thermodynamic variables. Here, we present a methodology to synthesize rhombohedral (3 R )-phase MoS 2 in a well-defined sword-like geometry having lengths up to 120 μm, uniform width of 2–3 μm and thickness of 3–7 nm by controlling the carrier gas flow dynamics from continuous mode to pulsed mode during the CVD growth process. Characteristic signatures such as high degree of circular dichroism (∼58% at 100 K), distinct evolution of low-frequency Raman peaks and increasing intensity of second harmonic signals with increasing number of layers conclusively establish the 3 R -phase of the material. A high value (∼844 pm/V) of second-order susceptibility for few-layer-thick MoS 2 swords signifies the potential of MoS 2 to serve as an atomically thin nonlinear medium. A field effect mobility of 40 cm 2 /V-s and I on / I off ratio of ∼10 6 further confirm the electronic-grade standard of this 3 R -phase MoS 2 . These findings are significant for the development of emerging quantum electronic devices utilizing valley-based physics and nonlinear optical phenomena in layered materials.

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