ECE Seminar - Direct growth of 2D materials: Development of novel growth methods and its multifunctional applications
10:30am - 11:30am
Lecture Theater K, Academic Building

2D materials have attracted much attention because of frontier electronic materials due to its superior electronic transport properties and mechanical flexibility in the future, making it a potential material for high performance and wearable electronics. Graphene is a typical 2D materials with high carrier mobility; however, it still cannot be applied in transistor due to the lack of bandgap. A new type of 2D semiconducting materials called transition metal dichalcogenides (TMDCs), which are layered structure with the strong in-plane bonding and weak out-of-plane interactions similar to graphite, have been intensively studied. Recent studies have predicted exceptional physical properties upon reduced dimensionality attracting lots of attention due to the versatile physical chemical behaviors. Nevertheless, the synthesis and the study of the fundamental physical properties of TMDs are still in early stages. The lack of a large-area and reliable synthesis method restrict exploring all the potential applications of the TMDs. Chemical vapor deposition (CVD) is a traditional approach for the growth of TMDs; nevertheless, the high growth temperature is a major drawback for its to be applied in flexible electronics. In this talk, an inductively coupled plasma (ICP) was used to synthesize Transition Metal Dichalcogenides (TMDs) through a plasma-assisted selenization process of metal oxide (MOx) at a low temperature, as low as 250 °C. Compared to other CVD processes the use of ICP facilitates the decomposition of the precursors at lower temperatures; therefore, the temperature required for the formation of TMDs can be drastically reduced. WSe2 was chosen as a model material system due to its technological importance as a p-type inorganic semiconductor with an excellent hole mobility. Large-area synthesis of WSe2 on polyimide (30 x 40 cm2) flexible substrates and 8-inch silicon wafers with good uniformity was demonstrated at the formation temperature of 250 °C as confirmed by Raman and X-ray Photoelectron (XPS) spectroscopy.  Furthermore, by controlling different H2/N2 ratios, hybrid WOx/WSe2 films can be formed at the formation temperature of 250 ºC as shown by TEM and confirmed by XPS. In addition, the plasma-engineered-1T/2H 3D-hierarchical WSe2/MoSe2 nanoscrews derived from the WOx/MoOxD-hierarchical nanoscrews through a low-temperature plasma-assisted selenization process with controlled shapes grown by a glancing angle deposition system (GLAD). The applications including (1) water splitting, (2) gas sensors, (3) photodetectors, (3) anode materials in secondary ion battery will be reported in this talk.

講者/ 表演者:
Prof. Yu-Lun Chueh
Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu, Taiwan

Prof. Yu-Lun Chueh received his Ph.D degree from department of materials science and engineering, National Tsing Hua University, Taiwan in 2006 and worked as postdoctor in electrical engineering and computer science, UC Berkeley from 2007-2009. He joined department of materials science and engineering, National Tsing Hua university in 2009. Currently, He is a professor in department of materials science and engineering, National Tsing Hua University, Taiwan. He has published 252 peer-reviewed papers and 25 patents with total citations >12000 and h-index of 52. Recently, he has been selected as an Associate Academician of Asia Pacific Academy of Materials on 2017 and Fellow of the Royal Society of Chemistry on 2018. The research activities of his lab are highly interdisciplinary and are committed to exploring new unpredicted levels of functional materials to enable new schemes on manipulating and processing of engineering nanomaterials in nanoelectronics and energy harvesting applications. He is committed to currently realize intellectual visions through studies on four major areas toward New Material Technologies: (1) Development of Cu(In, Ga)Se2 solar cell and its investigation on light harvesting behaviors, (2) Development of various method to synthesize different Graphene/two dimensional materials, (3) Low power resistive random access memory and (4) Growth of low dimensional materials and its possible functional application.


Prof. Zhiyong Fan