Title:
Fabrication of Nanoscale Microwave Detectors and Generators Based on the Ratchet Effect
Fabrication of Nanoscale Microwave Detectors and Generators Based on the Ratchet Effect
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Author(s)
Beck, Thomas J.
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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.
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Date Issued
2012-03-27
Extent
34:32 minutes
Resource Type
Moving Image
Resource Subtype
Lecture