Single QD nanowire photodetectors
DELFT, Netherlands – In another step toward quantum computing,
researchers have made a photodetector based on a single nanowire, in which the active
element is a single quantum dot (QD) with a volume of only 7000 nm3.
The nanowire, which was made of indium phosphide, was grown using
standard epitaxial techniques; sandwiching a thin segment in between with a lower
bandgap enabled the researchers to obtain the quantum dot. They used electron beam
lithography to contact a single nanowire to create the device.
The photocurrent from the nanowire detector: The yellow spot represents
the region where current is generated under illumination, the electrical contacts
are indicated in blue, and the nanowire is indicated in green. Courtesy of Val Zwiller,
Kavli Institute of Nanoscience at Delft University of Technology.
Quantum dots have discrete energy levels, so the device will detect
light in resonance only with the energy levels of the quantum dot. It functions
as a highly localized light detector and, because its dimensions are far below the
wavelength of light, it can detect light with very high spatial resolution, according
to the research team at the Kavli Institute of Nanoscience at Delft University of
The article appears in the journal Applied Physics Letters, Vol.
97, p. 113108 (2010).
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