Plasmonic effect on photovoltaic and photoconductive devices

تتشرّف دائرة الفيزياء بدعوتكم لحضور محاضرة علمية مع

البروفسو
ر عمر مناصرة من جامعة أركانساسس تحت عنوان:

Plasmonic effect on phot
ovoltaic and photoconductive devices

الأربعاء: 9/4/2014، الساعة 3:3
0 في كلية العلوم قاعة 240

Abstract: Coupling of surface
plasmon to optoelectronic devices extends the performance and operation of
these devices to limits that are currently unattainable with pristine devic
es as their sizes continue to decrease below 100 nanometers. The basic phys
ical concept of this coupling is that the optical nanoantennas act as photo
ns receptors to concentrate the light into deep sub-wavelength regions (nea
r field) with high optical density while the far field acts as a steering m
edium for the light. In general, the optical near field generates the char
ge carriers within the small device structure where the opto-electronic con
version occurs at the sub-wavelength scales with high spatial resolution an
d high response speed in optoelectronic devices. As the size of a photodet
ector, as an example, is reduced so it can be incorporated into integrate
d circuits, it becomes impossible to detect photons with a wavelength larg
er than the size of the photodetector itself. Thus, for the operation of s
uch devices, coupling with optical nanoantennas in the subwavelength regio
n is very crucial for realizing miniature (nanoscale) optoelectronic device
s for applications, such as speeding up computers and communication system
s. The size reduction of any optoelectronic device leads to two important a
dvantages: a) The dark current is reduced, which leads to a significant en
hancement in the device performance and figures of merit. b) The size of a
ny junction in the device will be reduced causing a substantial reduction i
n the junction capacitance leading to a much faster device since the cut of
f frequency is inversely proportional to the junction capacitance. In this
talk, we will present results on the growth of semiconductor nanocrystals
and metallic nanoparticles, methods of coupling metallic nanoparticles to
devices, and optical and electrical characterization of photovoltaic devic
es (solar cells) and uncooled photodetector before and after coupling them
to surface plasmons. The photovoltaic devices are mostly fabricated from I
nAs quantum dots structure while the uncooled photodetectors are fabricatedfrom either semi-insulating GaAs wafers or CdSe nanocrystals. The optical
nanoantennas that are coupled to the photodetectors are mostly in the form
of interdigital Ni/Au structures. Antireflection effect by using sol-gel n
anostructures will also be discussed.