Nano@Tech welcomes Institute for Electronics and Nanotechnology electrical engineer T.J. Beck on "Fabrication of Nanoscale Microwave Detectors and Generators Based on the Ratchet Effect"

Abstract:
Microwave radiation induced photovoltage in two-dimensional electron gas (2DEG) materials is a promising system for supporting carrier transport without the need for an externally applied bias. Typically these systems produce photovoltages in the nanovolt range, however it has been demonstrated that it is possible to enhance the photovoltage by taking advantage of the ratchet effect. We use the ratchet effect to produce current generating and detecting devices in a Si/SiGe heterostructure. To create a ratchet effect in our chosen material we use an asymmetrical scattering mechanism. The asymmetrical pattern acts as a preferential scatterer directing transport of the carriers in one direction resulting in a potential difference. In order to maximize the efficiency of the microwave irradiation the spacing of our asymmetrical pattern was carefully chosen to coincide with the mean free path of an electron. Beginning with a typical Hall Bar structure laid down on our Si/SiGe heterostructure we pattern an asymmetrical array within the Hall Bar using Electron Beam Lithography. This array is then transferred via plasma etch into the 2DEG material and the resulting system is exposed to microwave radiation. It is found that upon irradiation of our samples a potential difference can be measured across the Hall Bar Structure. These microwave devices have great potential for use in communication devices and wireless technology.

About the speaker:
TJ Beck is an engineer at the Institute for Electronics and Nanotechnology at the Georgia Institute of Technology. He obtained his BS in Physics with a minor in music from Loyola University New Orleans in 2001 where he concentrated in the fields of electronics, optics, and Jazz performance. After graduating from Loyola University TJ attended Tulane University and received his MS in Physics in 2004. While at Tulane, he focused on surface interactions at the atomic level and published several papers on the subject. TJ's primary role at the IEN is developing nanofabrication processes for external academic and industrial customers. He is also involved with graphene growth in the IEN's FirstNano Graphene Furnace as well as thin film deposition using the Cambridge Plasma enhanced ALD systems.