Rajabali, Mona
Date: Wednesday, October 9, 2019
Time: 14:00
Place: ETH Zurich, Hönggerberg, HPF G 6
Host: Jérôme Faist
High-performance transistors using exfoliation-less direct formation of large-area phosphorene sheets on silicon substrates
Mona Rajabali
University of Tehran, Iran
Along with recent advances in technology, black-phosphorous (BP) has aroused great excitement among scientists following its fascinating structure and properties such as high carrier mobility, anisotropic optical and electrical properties and tunable direct bandgap. Mechanical exfoliation is known to be the main method to transfer BP to the desired substrate in order to realize optical and electrical devices, although solution-based exfoliation is another alternative. All these techniques suffer from lack of suitable interface and of large area flakes. Since chemical vapor deposition is not immediately accessible for this material, direct formation of phosphorene on desired substrates has been a challenge.
Here, for the first time, we report the fabrication of phosphorene-based high-performance field effect transistors using direct formation of highly-crystalline phosphorene sheets through phase transformation method, with no need to bulk BP or further exfoliation and transfer. Since the growth (phase transformation) occurs on silicon substrates, the device can be fabricated on the same substrate with no need to extra transfer or exfoliation. Two different techniques as laser-assisted crystallization and a sequential plasma-assisted process have been introduced, both leading to remarkable results. Our results indicate a straightforward strategy to realize favorite high quality two-dimensional structures which opens a new avenue to phosphorene-based optoelectronic devices.
Bio: Mona Rajabali received her B.Sc. and M.Sc. degrees in Solid state Physics in K.N.Toosi University in Tehran, Iran. She is currently a Ph.D. candidate in Nanotechnology at University of Tehran, Iran. She is working at Thin Film and Nanoelectronic Lab (TF-NEL) at Electrical Engineering department. In her Ph.D. program, she has worked on the device fabrication and characterization of two-dimensional materials, including phosphorene, antimonene and tungsten disulfide (WS2). Beside her full acquaintance with cleanroom procedures, material characterization and electrical measurements of nano-devices characteristics, she also participates in several other projects including: MAP sensor prototype fabrication for industrial mass production, growth of large area WS2 sheets and employing phosphorene sheets in bio-sensing applications. She is also the senior researcher in High-Resolution TEM (HR-TEM) team at TF-NEL Lab which had the accomplishment of taking HR-TEM image as the first research group in Iran.