|Paul David Cunningham
The objective of this research effort is to understand the properties of valley excitons and charge carriers in two-dimensional transition metal dichalcogenides monolayers and their heterostructures. Additionally, we seek to control those properties through strong light-mater interactions induced by plasmonic cavities and metasurfaces.
In this multidisciplinary effort, members of our team fabricate single layer transition metal dichalcogenide materials (e.g., WS2, MoSe2, etc.) by direct synthesis, e.g. chemical vapor deposition. Transfer techniques are used to assemble vertical heterostructures. Metal colloidal nanostructures will be synthesized and nano-antenna structures deposited using lithographic techniques to assemble plasmonic cavities. A wide range of instruments are employed to characterize these materials: photoluminescence mapping, Raman mapping, atomic force microscopy, scanning tunneling microscopy, etc. Additional instrumentation resides in the Nanoscience Institute, a shared facility open to researchers on our campus.
Our group is particularly interested in the behavior of valley excitons, bound trions, charge carriers, and interlayer excitons that influence the optoelectronic properties of these systems, which we interrogate with a variety of static and time-resolved spectroscopic techniques. Our laser facility includes regeneratively amplified titanium sapphire laser systems, optical parametric amplifiers, a picosecond dye laser system, a time-correlated photon counting system for time-resolved photoluminescence with detectors spanning the visible and near-infrared regions, a commercial fluorescence spectrometer, home-built broadband transient absorption spectroscopy and two-color pump-probe spectroscopy setups, etc.
Qualified candidates should possess or be completing a PhD in physics, chemistry, or related discipline with experience in time-resolved spectroscopy. Ultrafast spectroscopy and time-resolved microscopy are a plus, as is familiarity with photophysics in either two-dimensional transition metal dichalcogenides, other low dimensional semiconductors, organic semiconductors, or other excitonic systems.
Recent team publications:
Cunningham, Jonker, et al., J. Phys. Chem. Lett. 7, 5242 (2016) – Exciton-Exciton Annihilation
Cunningham, Jonker et al., ACS Nano 11, 12601 (2017) – Bandgap Renormalization
Hanbicki, Jonker, et al., ACS Nano 12, 4719 (2018) – Interlayer Excitons in Heterostructures
Rosenberger, Jonker, et al., ACS Nano 13, 904 (2019) – Single Photon Emitters
Photophysics; 2D materials; Transition metal dichalcogenides; van der Waals, Valleytronics; Spectroscopy; Microscopy; Time-Resolved