Ultrafast intrinsic photoresponse and direct evidence of sub-gap states in liquid phase exfoliated MoS2 thin films

Sujoy Ghosh, Andrew Winchester, Baleeswaraiah Muchharla, Milinda Wasala, Simin Feng, Ana Laura Elias, M. Bala Murali Krishna, Takaaki Harada, Catherine Chin, Keshav Dani, Swastik Kar, Mauricio Terrones, Saikat Talapatra

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30 Scopus citations

Abstract

2-Dimensional structures with swift optical response have several technological advantages, for example they could be used as components of ultrafast light modulators, photo-detectors, and optical switches. Here we report on the fast photo switching behavior of thin films of liquid phase exfoliated MoS 2, when excited with a continuous laser of λ=658nm (E=1.88eV), over a broad range of laser power. Transient photo-conductivity measurements, using an optical pump and THz probe (OPTP), reveal that photo carrier decay follows a bi-exponential time dependence, with decay times of the order of picoseconds, indicating that the photo carrier recombination occurs via trap states. The nature of variation of photocurrent with temperature confirms that the trap states are continuously distributed within the mobility gap in these thin film of MoS2, and play a vital role in influencing the overall photo response. Our findings provide a fundamental understanding of the photo-physics associated with optically active 2D materials and are crucial for developing advanced optoelectronic devices.

Original languageEnglish (US)
Article number11272
JournalScientific reports
Volume5
DOIs
StatePublished - Jul 15 2015

All Science Journal Classification (ASJC) codes

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    Ghosh, S., Winchester, A., Muchharla, B., Wasala, M., Feng, S., Elias, A. L., Krishna, M. B. M., Harada, T., Chin, C., Dani, K., Kar, S., Terrones, M., & Talapatra, S. (2015). Ultrafast intrinsic photoresponse and direct evidence of sub-gap states in liquid phase exfoliated MoS2 thin films. Scientific reports, 5, [11272]. https://doi.org/10.1038/srep11272