Seminars

Who: Andres Castellanos-Gomez, Delft University of Technology, Delft, Netherlands

In this talk I will introduce and motivate the study of the mechanical, electrical and optical properties of atomically thin crystals different than graphene. I will focus on Molybdenum Disulphide which is considered a case of special interest. Single-layer MoS₂ is an attractive two-dimensional material that combines the mechanical flexibility of graphene with a large direct bandgap. While graphene is very interesting as a transparent electrode, its lack of a bandgap limits its usefulness in semiconducting and optoelectronic devices. Atomically thin MoS₂, on the other hand, has a large intrinsic bandgap. This attractive feature has been employed to fabricate many devices not possible in graphene, such as field-effect transistors with high mobility and current on/off ratio, logic gates and efficient photo-transistors. Our work on MoS₂ has been focused on developing new methods to fabricate single layer MoS₂ [1] and to characterize the intrinsic mechanical [2], optical and electrical properties [3-4] of this atomically thin material.Here, I will show an overview of our last results paying special attention to our studies on the photocurrent generation in single layer MoS₂[4] and the strain engineering in atomically thin MoS₂ [5].

References

[1] Castellanos-Gomez, A., et al., Laser-Thinning of MoS2: On Demand Generation of a Single-Layer Semiconductor. Nano Letters, 2012, 12(6): p. 3187-3192.

[2] Castellanos-Gomez, A., et al., Elastic Properties of Freely Suspended MoS2 Nanosheets. Advanced Materials, 2012, 24(6): p. 772-775.

[3] Castellanos-Gomez, A., et al., Electric-Field Screening in Atomically Thin Layers of MoS2: the Role of Interlayer Coupling. Advanced Materials, 2013, 25(6): p. 899-903.

[4] Buscema, M., et al., Large and Tunable Photothermoelectric Effect in Single-Layer MoS2. Nano Letters, 2013, 13(2), p. 358?363

[5] Castellanos-Gomez, A., et al., Local strain engineering in atomically thin MoS₂. arXiv:1306.3804 (2013)

"Atomically thin MoS2: a two dimensional semiconductor beyond graphene "