CVD Synthesis of Twisted Bilayer WS<sub>2</sub> with Tunable Second Harmonic Generation.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38328994.
- Also identified by DOI 10.1002/adma.202313638.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
The introduction of rotational freedom by twist angles in twisted bilayer (TB) transition metal dichalcogenides (TMDCs) can tailor the inherent properties of the TMDCs, which provides a promising platform to investigate the exotic physical properties. However, direct synthesis of high-quality TB-TMDCs with full twist angles is significantly challenging due to the substantial energy barriers during crystal growth. Here, a modified chemical vapor deposition strategy is proposed to synthesize TB-WS<sub>2</sub> with a wide twist angle range from 0° to 120°. Utilizing a tilted SiO<sub>2</sub>/Si substrate, a gas flow disturbance is generated in the furnace tube to create a heterogeneous concentration gradient of the metal precursor, which provides an extra driving force for the growth of TB-WS<sub>2</sub>. The Raman and photoluminescence results confirm a weak interlayer coupling of the TB-WS<sub>2</sub>. High-quality periodic Moiré patterns are observed in the scanning transmission electron microscopy images. Moreover, owing to the strong correlation between the nonlinear optical response and the twisted crystal structure, tunable second harmonic generation behaviors are realized in the TB-WS<sub>2</sub>. This approach opens up a new avenue for the direct growth of high-crystalline-quality and pristine TB-TMDCs and their potential applications in nonlinear optical devices.