Acoustically-Driven Trion and Exciton Modulation in Piezoelectric Two-Dimensional MoS sub(2)

• Published in: Nano letters Vol. 16; no. 2; pp. 849 - 855
• Main Authors: Rezk, Amgad R, Carey, Benjamin, Chrimes, Adam F, Lau, Desmond WM, Gibson, Brant C, Zheng, Changxi, Fuhrer, Michael S, Yeo, Leslie Y, Kalantar-zadeh, Kourosh
• Format: Journal Article
• Language: English
• Published: 10-02-2016
• Subjects: Electric fields; Electric power generation; Excitation; Molybdenum disulfide; Photoluminescence; Piezoelectricity; Trions; Two dimensional
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.5b02826

By exploiting the very recent discovery of the piezoelectricity in odd-numbered layers of two-dimensional molybdenum disulfide (MoS sub(2)), we show the possibility of reversibly tuning the photoluminescence of single and odd-numbered multilayered MoS sub(2) using high frequency sound wave coupling. We observe a strong quenching in the photoluminescence associated with the dissociation and spatial separation of electrons-holes quasi-particles at low applied acoustic powers. At the same applied powers, we note a relative preference for ionization of trions into excitons. This work also constitutes the first visual presentation of the surface displacement in one-layered MoS sub(2) using laser Doppler vibrometry. Such observations are associated with the acoustically generated electric field arising from the piezoelectric nature of MoS sub(2) for odd-numbered layers. At larger applied powers, the thermal effect dominates the behavior of the two-dimensional flakes. Altogether, the work reveals several key fundamentals governing acousto-optic properties of odd-layered MoS sub(2) that can be implemented in future optical and electronic systems. Keywords: Two-dimensional materials; MoS sub(2); surface acoustic waves; photoluminesence; exciton; trion; piezoelectricity