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Irákleion, Greece

Pantazis A.K.,Biosensors | Pantazis A.K.,University of Michigan | Konstantinidis G.,Microelectronics Research Group | Gizeli E.,University of Crete
IEEE Sensors Journal | Year: 2014

Lamb-wave acoustic devices have been proposed as a promising platform for sensing applications. In this paper, the performance of a GaN Lamb wave device as a liquid-based mass sensor is studied with respect to the effect of environmental parameters to the device performance, namely, the liquid flow-rate, device temperature, and presence of a thin gold film deposited on the GaN membrane. © 2013 IEEE. Source


Hocevar M.,French National Solar Energy Institute | Thanh Giang L.T.,CNRS Neel Institute | Songmuang R.,CNRS Neel Institute | Den Hertog M.,CNRS Neel Institute | And 6 more authors.
Applied Physics Letters | Year: 2013

We observe a systematic red shift of the band-edge of passivated GaAs/Al0.35Ga0.65As core-shell nanowires with increasing shell thickness up to 100 nm. The shift is detected both in emission and absorption experiments, reaching values up to 14 meV for the thickest shell nanowires. Part of this red shift is accounted for by the small tensile strain imposed to the GaAs core by the AlGaAs shell, in line with theoretical calculations. An additional contribution to this red shift arises from axial piezoelectric fields which develop inside the nanowire core due to Al fluctuations in the shell. © 2013 AIP Publishing LLC. Source


Mitioglu A.A.,INSA Toulouse | Mitioglu A.A.,Institute of Applied Physics | Plochocka P.,INSA Toulouse | Deligeorgis G.,Microelectronics Research Group | And 4 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2014

Resonant Raman spectra of single-layer WS2 flakes are presented. A second-order Raman peak (2LA) appears under resonant excitation with a separation from the E2g1 mode of only 4cm-1. Depending on the intensity ratio and the respective linewidths of these two peaks, any analysis that neglects the presence of the 2LA mode can lead to an inaccurate estimation of the position of the E2g1 mode, leading to a potentially incorrect assignment for the number of layers. Our results show that the intensity of the 2LA mode strongly depends on the angle between the linear polarization of the excitation and detection, a parameter that is neglected in many Raman studies. © 2014 American Physical Society. Source


Pantazis A.K.,University of Crete | Pantazis A.K.,Microelectronics Research Group | Gizeli E.,University of Crete | Gizeli E.,Institute of Molecular Biology and Biotechnology | Konstantinidis G.,Microelectronics Research Group
Applied Physics Letters | Year: 2010

Lamb-wave devices are characterized by high sensitivity to surface perturbations due to acoustic energy confinement in a thin piezoelectric membrane. In this paper, a Lamb-wave delay line device based on a single crystalline GaN membrane is presented. The observed operating frequency of 178.82 MHz was found to be in excellent agreement with numerical analysis predictions. The device as a chemical sensor was evaluated during the application of various concentrations of glycerol on the device surface; its ability to operate as a biosensor was also assessed during the detection of the specific binding of a protein (IgG) to the device surface. © 2010 American Institute of Physics. Source


Askitopoulos A.,University of Southampton | Ohadi H.,University of Southampton | Kavokin A.V.,University of Southampton | Kavokin A.V.,Saint Petersburg State University | And 5 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We demonstrate experimentally the condensation of exciton polaritons through optical trapping. The nonresonant pump profile is shaped into a ring and projected to a high quality factor microcavity where it forms a two-dimensional repulsive optical potential originating from the interactions of polaritons with the excitonic reservoir. Increasing the population of particles in the trap eventually leads to the emergence of a confined polariton condensate that is spatially decoupled from the decoherence inducing reservoir, before any buildup of coherence on the excitation region. In a reference experiment, where the trapping mechanism is switched off by changing the excitation intensity profile, polariton condensation takes place for excitation densities more than two times higher and the resulting condensate is subject to much stronger dephasing and depletion processes. © 2013 American Physical Society. Source

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