Browsing by Subject "Metamaterial antennas"

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Open Access
Development of micro-structured metamaterials for innovative antenna layouts
(IEEE, 2007) Bilotti F.; Capolino F.; Gonzalo, R.; Özbay, Ekmel; Romeu J.; Schuchinsky, A.; Tretyakov, S.; Vardaxoglou, Y.
In this paper, we present the joint activities developed in the frame of the FP6 European Network of Excellence METAMORPHOSE in the field of new micro-structured materials for antenna applications. One of the key scientific goals of the research efforts developed within this network is to design innovative micro-structured materials to improve the performances of conventional radiators. Miniaturization, multi-functionality, reduced interference with electronic circuitry, are some of the main challenges in the design of antennas for the next generation of electronic transceivers in the microwave frequency range. The employment of different classes of metamaterials in innovative antenna layouts has been demonstrated to be effective to reach most of the desired goals. The theoretical, numerical and experimental efforts carried out by the leading European institutions working in this field, in fact, show how metamaterial antennas with unusual features are ready to push the innovation in the antenna research. The collaborative dimension of this research is described in this paper, as well as the related scientific achievements. © 2007 EuMA.
Open Access
Ultra-low-cost near-infrared photodetectors on silicon
(SPIE, 2015-02) Nazirzadeh, M. Amin; Atar, Fatih B.; Turgut, B. Berkan; Okyay, Ali Kemal
We demonstrate Silicon-only near-infrared (NIR) photodetectors (sensitive up to 2000 nm) that meet large-scale ultralow-cost fabrication requirements. For the detection of infrared photons, we use metal nanoislands that form Schottky contact with Silicon. NIR photons excite plasmon resonances at metal nanoislands and plasmons decay into highly energetic charge carriers (hot electrons). These hot electrons get injected into Silicon (internal photoemission), resulting in photocurrent. Several groups have studied plasmonic nanoantennas using high resolution lithography techniques. In this work, we make use of randomly formed nanoislands for broad-band photoresponse at NIR wavelengths. We observe photoresponse up to 2000 nm wavelength with low dark current density about 50 pA/μm2. The devices exhibit photoresponsivity values as high as 2 mA/W and 600 μA/W at 1.3 μm and 1.55 μm wavelengths, respectively. Thin metal layer was deposited on low-doped n-type Silicon wafer. Rapid thermal annealing results in surface reconstruction of the metal layer into nanoislands. Annealing conditions control the average size of the nanoislands and photoresponse of the devices. An Al-doped Zinc Oxide (AZO) layer was deposited on the nanoislands using thermal atomic layer deposition (ALD) technique to acts as a transparent conductive oxide (TCO) and patterned using photolithography. AZO film creates electrical connection between the nanoislands and also makes a heterojunction to Silicon. Simple and scalable fabrication on Si substrates without the need for any sub-micron lithography or high temperature epitaxy process make these devices good candidates for ultra-low-cost broad-band NIR imaging and spectroscopy applications. © 2015 SPIE.