1. THE IBY AND ALADAR FLEISHMAN FACULTY OF ENGINEERING
SCHOOL OF ELECTRICAL ENGINEERING
DEPT OF PHYSICAL ELECTRONICS
Thursday March 13th – 15:00
Nanoelectromechanical properties of thin graphite layers
Speaker: Elad Koren
Armin W.Knoll, Emanuel Loertscher and Urs Duerig
IBM Research-Zurich, 8803 Ruschlikon, Switzerland
Abstract:
Ever since the successful fabrication of monolayer graphene, a two-dimensional honeycomb lattice of sp2-bonded carbon atoms, from highly oriented pyrolytic graphite (HOPG) in 2004, its perfect two-dimensional crystal has become a topic of great interest. The superior electronic, thermal, and mechanical properties make it a promising component in the next generation of electronic, optoelectronic, sensing and energy harvesting/storage devices. Due to the layered structure of graphite, it is enough to comprise only two or more graphene layers in order to realize large un-isotropic material properties, both electronic and mechanical. Properties like superlubricty and self-retracting motion were experimentally observed in HOPG demonstrating that “smart”, low-energy dissipation nano-electromechanical (NEM) elements can be realized using 2D layered materials. While these phenomenons were observed in such system, this behavior is still not fully quantify and explained. Furthermore, while the superlubricity behavior has been experimentally studied using frictional force microscopy (FFM) for constant contact sizes, we study here the case for variable contact sizes i.e. the frictional force is measured for different overlaps between two adjacent graphitic layers. This setup allows us to directly measure the exfoliation energy and the required forces for sliding one graphitic layer on top of the other. We then demonstrate how these forces can be used to realize variable, constant and zero force mechanical element. In addition, we have been able to measure the force oscillations of the Moir’e structure formed between two relatively rotated graphitic layers using our setup which suggest that even in the “superlubricity” state there is still an intrinsic source for energy dissipation. The second part will discuss the combined electromechanical properties between two adjacent layers of graphene both in the pristine (AB-stacking) and in a turbostratic state.
The lecture will take place in the kitot build. Room # 011, at 15:00