126 research outputs found
An all-ZnO microbolometer for infrared imaging
Cataloged from PDF version of article.Microbolometers are extensively used for uncooled infrared imaging applications. These imaging units generally employ vanadium oxide or amorphous silicon as the active layer and silicon nitride as the absorber layer. However, using different materials for active and absorber layers increases the fabrication and integration complexity of the pixel structure. In order to reduce fabrication steps and therefore increase the yield and reduce the cost of the imaging arrays, a single layer can be employed both as the absorber and the active material. In this paper, we propose an all-ZnO microbolometer, where atomic layer deposition grown zinc oxide is employed both as the absorber and the active material. Optical constants of ZnO are measured and fed into finite-difference-time-domain simulations where absorption performances of microbolometers with different gap size and ZnO film thicknesses are extracted. Using the results of these optical simulations, thermal simulations are conducted using finite-element-method in order to extract the noise equivalent temperature difference (NETD) and thermal time constant values of several bolometer structures with different gap sizes, arm and film thicknesses. It is shown that the maximum performance of 171 mK can be achieved with a body thickness of 1.1 μm and arm thickness of 50 nm, while the fastest response with a time constant of 0.32 ms can be achieved with a ZnO thickness of 150 nm both in arms and body. © 2014 Elsevier B.V. All rights reserved
Plasmonically enhanced hot electron based photovoltaic device
Cataloged from PDF version of article.Hot electron photovoltaics is emerging as a candidate for low cost and ultra thin solar cells. Plasmonic means can be utilized to significantly boost device efficiency. We separately form the tunneling metal-insulator-metal (MIM) junction for electron collection and the plasmon exciting MIM structure on top of each other, which provides high flexibility in plasmonic design and tunneling MIM design separately. We demonstrate close to one order of magnitude enhancement in the short circuit current at the resonance wavelengths. (C) 2013 Optical Society of Americ
Metastasis of breast carcinoma to the external auditory canal: Report of an unusual case and literature review
We present a case of metastasis of the external auditory canal (EAC) from a primary breast carcinoma in a 53-year-old female with a review of the literature. The patient had been diagnosed with a primary carcinoma 4 years previously. The metastasis had developed recently in her left EAC and presented as a bulky, fleshy, bleeding mass. The mass was causing hearing loss on the left due to complete obstruction in the left EAC. The mass was incompletely removed with a surgical operation and histopathologically metastasis was proven. Although there are few case reports in the literature of various cancers metastasizing to the EAC, metastasis in the EAC from the breast carcinoma is exceedingly rare and only one case has been reported in the literature so far
Plasmonically enhanced hot electron based photovoltaic device
Hot electron photovoltaics is emerging as a candidate for low cost and ultra thin solar cells. Plasmonic means can be utilized to significantly boost device efficiency. We separately form the tunneling metal-insulator-metal (MIM) junction for electron collection and the plasmon exciting MIM structure on top of each other, which provides high flexibility in plasmonic design and tunneling MIM design separately. We demonstrate close to one order of magnitude enhancement in the short circuit current at the resonance wavelengths. © 2013 Optical Society of America
Semiconductor-less photovoltaic device
We demonstrate a novel semiconductor-less photovoltaic device and investigate the plasmonic effects on this device structure. The device is made of metal and dielectric layers and the operation is based on hot carrier collection. We present the use of surface plasmons to improve energy conversion efficiency. The field localization provided by surface plasmons confine the incident light in the metal layer, increasing the optical absorption and hot electron generation rate inside the metal layer. The device consists of two tandem MIM (metal-insulator-metal) junctions. Bottom MIM junction acts as a rectifying diode and top MIM junction is used to excite surface plasmons. The device operation principle as well as the topology will be discussed in detail. © 2013 IEEE
Some anisotropic universes in the presence of imperfect fluid coupling with spatial curvature
We consider Bianchi VI spacetime, which also can be reduced to Bianchi types
VI0-V-III-I. We initially consider the most general form of the energy-momentum
tensor which yields anisotropic stress and heat flow. We then derive an
energy-momentum tensor that couples with the spatial curvature in a way so as
to cancel out the terms that arise due to the spatial curvature in the
evolution equations of the Einstein field equations. We obtain exact solutions
for the universes indefinetly expanding with constant mean deceleration
parameter. The solutions are beriefly discussed for each Bianchi type. The
dynamics of the models and fluid are examined briefly, and the models that can
approach to isotropy are determined. We conclude that even if the observed
universe is almost isotropic, this does not necessarily imply the isotropy of
the fluid (e.g., dark energy) affecting the evolution of the universe within
the context of general relativity.Comment: 17 pages, no figures; to appear in International Journal of
Theoretical Physics; in this version (which is more concise) an equation
added, some references updated and adde
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