The Waterloo Institute for Nanotechnology (WIN) and the Center for Nanointegration Duisberg-Essen (CENIDE) are pleased to present Antonio di Bartolomeo, Professor in the Department of Physics at the University of Salerno, for a joint 2D-MATURE seminar titled "Electrical Conduction and Photoconduction in 2D Materials Based Transistors"
NOW BEING HELD VIRTUALLY!
Electrical Conduction and Photoconduction in 2D Materials Based Transistors
Two-dimensional (2D) materials hold great promise for electronic and optoelectronic applications. The atomic thickness enables highly scaled field-effect transistors with reduced short-channel effects; the strong interaction with light and the tunable bandgap can be exploited for sensitive and broadband photodetection.
The electrical transport and the photoresponse of 2D transition metal dichalcogenides (TMDs) such as MoS2, ReS2, and PtSe2 are investigated as a function of temperature and pressure.
The temperature-dependent transistor output and transfer characteristics are used to estimate the carrier mobility and the trap density as well as the Schottky barrier formed by 2D materials with the metal contacts. It id shown that air pressure can control the transistor channel conductance, the charge carrier polarity, and the hysteresis in the transfer characteristics.
It is found that the 2D materials photoconductivity is generally enhanced by the increasing temperature and decreasing pressure. Through time-resolved photocurrent measurements, it is shown that the device photoresponse is dominated by slow photobolometric and slower photogating effects that are attributed to charge trapping/detrapping by shallow and deeper intragap states as well as to desorption of polar adsorbates. The temperature dependence of photoconductivity is explained by photoinduced desorption of adsorbates, such as O2 and H2O molecules, that enhance the n-doping level of MoS2 and ReS2 and suppress the p-doping level of PtSe2. The desorption of adsorbates is facilitated at low pressure, which also suppresses the readsorption mechanisms, thus yielding a persistent photocurrent. The light-induced desorption of adsorbates can cause negative photoconductivity in p-type materials such as PtSe2.
This presentation covers several aspects of electrical transport observed in 2D materials and emphasizes the key role that intrinsic defects and adsorbates have in their pressure- and temperature-dependent photoresponse.
 A. Di Bartolomeo, …, Materials Today Nano, 2023, 24, 100382
 A. Kumar,…, A. Di Bartolomeo, Journal of Physics and Chemistry of Solids 2023, 179, 111406
 K. Intonti, … A. Di Bartolomeo, ACS Applied Materials & Interfaces 2023, am-2023-12973e.R1 in press
 K. Intonti, … A. Di Bartolomeo, Advanced Electronic materials 2023, 9, 2300066
 A. Grillo, …A. Di Bartolomeo, Advanced Functional Materials 2021, 3, 2105722
Antonio di Bartolomeo is a full professor of Experimental Condensed Matter Physics at the University of Salerno, Italy where he teaches semiconductor device physics and nanoelectronics.
His present research interests include optical and electrical properties of nanostructured materials such as carbon nanotubes, graphene, and 2D materials, van der Waals heterostructures and Schottky junctions, field-effect transistors, non-volatile memories, solar cells, photodetectors, field emission devices, and supercapacitors.
He has been invited speaker in over 100 international conferences and has authored about 200 publications in peer-reviewed journals, two physics textbooks, and two patents. He is serving as the editor-in-chief of IOP Nano Express and IET Micro & Nano Letters, the section editor-in-chief of MDPI Nanomaterials and is an Editorial Board member of several journals.