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Wenjing Jie, Seminar, Mar. 12, 2015

Published: March 4, 2015

Topic:

Optical and Electronic Properties of Graphene and Graphene-Like Two-Dimensional Materials


Abstract:

Graphene, a single carbon layer, has represented a promising direction for future device applications, benefiting from its unique structure and fascinating properties. Motivated by the triumph and also the limitation of graphene for electronic and optical applications, atomically thin layers of metal dichalcogenides are attracting extensive interest as a class of graphene-like semiconductors with a desired and tunable band-gap in the visible frequency range. Here I will focus on our recent studies of electronic and optical devices based on graphene and graphene-like two-dimensional (2D) material of gallium selenide (GaSe). For graphene, a non-volatile memory and a Schottky junction solar cell has been fabricated by integrating graphene and ferroelectric (PMN-PT) as well as semiconductor (GaAs), respectively. The electronic and optoelectronic characteristics will be shown based on the hybrid structures. Furthermore, the vibrational properties of graphene will be discussed by strain engineering originating from the ferroelectric material. For GaSe, a strong layer- and power-dependent second harmonic generation will be reported at few-layer GaSe sheets when excited by femtosecond pulse laser. The simultaneous observation of two-photon excited fluorescence indicates unique optical properties in atomically thin GaSe sheets. Our free energy calculations based on first-principles methods support the observed nonlinear optical phenomena in such atomically thin layers. These fundamental studies will aid further research of 2D materials and show promise for their future applications in nanoelectronics and nanophotonics.


Personal profile:

Wenjing Jie

Department of Applied Physics

The Hong Kong Polytechnic University



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