Monday, April 18, 2016
Abstract-Manipulation of terahertz waves by work function engineering in metal-graphite structures
We manipulate the transient terahertz (THz) emitted from metal-graphite where potential barriers were formed because of differences. To flip the phase of the THz two distinct groups of metals were evaporated on -type highly oriented pyrolytic (HOPG): group A, which consisted of Pt, and with larger than that of HOPG and group B, which consisted of Al and Ti with smaller than that of HOPG. The phase of the transient THz lineshapes from group A was opposite to that of group B under infrared laser excitation, which is indicative of opposite band bending and concomitant interfacial for ambipolar transport at the metal-graphite junctions. The amplitude of the THz could also be manipulated by the differences and further quantified based on modified minority carrier mobilities at the depletion regions.