The High Energy Theory Group has active programs in all areas of particle physics, encompassing Standard Model and beyond, and lattice gauge techniques. Topics of interest include electroweak symmetry breaking and related phenomena, collider physics, precision measurements, physics of flavor, higher order calculations, neutrino interactions, phenomenology of dark sectors, and particle cosmology.
JUN
11
Monday
Center for Functional Nanomaterials Seminar
"Heterostructures for Nanoelectronics and Photovoltaics"
Presented by Deep Jariwala, University of Pennsylvania
1:30 pm, CFN, Bldg. 735, Conference Room A, 1st Floor
Monday, June 11, 2018, 1:30 pm
Hosted by: Don DiMarzio & Mircea Cotlet
The isolation of a growing number of two-dimensional (2D) materials has inspired worldwide efforts to integrate distinct 2D materials into van der Waals (vdW) heterostructures. While a tremendous amount of research activity has occurred in assembling disparate 2D materials into "all-2D" van der Waals heterostructures,1, 2 this concept is not limited to 2D materials alone. Given that any passivated, dangling bond-free surface will interact with another via vdW forces, the vdW heterostructure concept can be extended to include the integration of 2D materials with non-2D materials that adhere primarily through noncovalent interactions.3 In the first part of this talk I will present our work on emerging mixed-dimensional (2D + nD, where n is 0, 1 or 3) heterostructure devices performed at Northwestern University. I will present two distinct examples of gate-tunable p-n heterojunctions.4-6 I will show that when a single layer n-type molybdenum disulfide (MoS2) (2D) is combined with p-type semiconducting single walled carbon nanotubes (1D), the resulting p-n junction is gate-tunable and shows a tunable diode behavior with rectification as a function of gate voltage and a unique anti-ambipolar transfer behavior.4 The same concept when extended to p-type organic small molecule semiconductor (pentacene) (0D) and n-type 2D MoS2 leads to a tunable p-n junction with a photovoltaic effect and an asymmetric anti-ambipolar transfer response.6 I will present the underlying charge transport and photocurrent responses in both the above systems using a variety of scanning probe microscopy techniques as well as computational methods. Finally, I will show that the anti-ambipolar field effect observed in the above systems can be generalized to other semiconducting heterojunction systems and extended over large areas with practical applications in wireless communication circuits.5 The second part of talk will discuss my more recent work performed at Caltech on photovo