Salah E. El-Zohary

Resonance-based integrated plasmonic nanosensor for lab-on-chip applications

Abstract. An integrated plasmonic resonator was proposed and analyzed. The detection performance of our device has been numerically verified by finite-difference time-domain simulations. The spectral sensitivity obtained was found to be 700  nm/RIU, where RIU is the refractive index unit. Our proposed sensor was found to have a detection limit in the order of 10−6  RIU. The plasmonic sensor could be fabricated using focus ion beam milling. Our design leads to an ultra-compact sensor suitable for on-chip sensing applications associated with a high sensitivity. For biosensing, the proposed sensor could have the ability for a specific capture of biomolecules at the sensor surface that enables for quantification of the biomolecules.

Electrical Characterization of Nanopolyaniline/Porous Silicon Heterojunction at High Temperatures

Nanopolyaniline/p-type porous silicon (NPANI/PSi) heterojunction films were chemically fabricated via in situ polymerization. The composition and morphology of the nanopolymer were confirmed using Fourier transform infrared, scanning electron microscopy, UV-visible, and transmission electron microscopy techniques. The results indicated that the polymerization took place throughout the porous layer. The I-V measurements, performed at different temperatures, enabled the calculation of ideality factor, barrier height, and series resistance of those films. The obtained ideality factor showed a nonideal diode behavior. The series resistance was found to decrease with increasing temperature.

Design optimization and fabrication of Mach- Zehnder interferometer based on MIM plasmonic waveguides.

We proposed and designed a compact unbalanced Mach-Zehnder interferometer (MZI) based on metal/insulator/metal (MIM) plasmonic waveguides for ultrafast optical signal processing. The MZI was fabricated by a lithography technique and we provide, for the first time experimental evaluation of the transmission performance of the MZI using MIM PWGs. The experimental results were in good agreement with the numerical simulations. The proposed structure could be considered as a key device for on-chip optical integrated circuits.

Design optimization and fabrication of plasmonic nano sensor

We propose a novel sensing system using the plasmonic resonator for detecting a minor changes of the refractive index. The detection performance of our device has been numerically evaluated by (FDTD) finitedifference time-domain simulations. Our design can be easily fabricated using the focus ion beam milling technique. It leads to a highly compact sensor in terms with high sensitivity and high detection limit.

Plasmon resonance sensors for compact plasmonic integrated device (Conference Presentation)

Surface plasmon polariton (SPP) provide the field enhancement and localization beyond the diffraction limit of light. By using SPP, we have numerically designed tiny resonance sensors as plasmonic integrated devices with silver or gold as metal material for near infrared region of light. We will present our recent work for the sensors. The sensors are the combination of the plasmon resonator and MIM channel plasmon waveguide with the gap of ~150 nm and the hight of ~1.5 micron. The typical area size of sensor is order of 1 square micrometers and their sensitivity for temperature or stress change is comparable to current optical sensors. We have fabricated some fundamental structure of the device by using the electron beam lithography and will show experimental optical characteristics for IR region.

A simple and low cost method to fabricate well controllable silicon nanowires based on electrostatic adsorption of PS nanospheres

We propose a simple and low cost method to fabricate well-controllable and organized silicon nanowire (SiNWs) arrays based on electrostatic adsorption of a monolayer of polystyrene nanospheres on Si substrate. The proposed method has been used to demonstrate the controllability of density of SiNWs avoiding complicated and expensive lithography techniques. The proposed method led to well-organized SiNWs and controlling SiNWs size and density for specific optoelectronic and nanophotonic applications.

Heterojunction of poly (o-toluidine) and silicon nanowires

Abstract. A nanostructured poly (o-toluidine)/silicon nanowires (NPOT/SiNWs) heterojunction has been fabricated with a low cost and simple techniques, where NPOT has been in situ polymerized upon SiNWs synthesized by chemical etching of a silicon wafer. The morphology of SiNWs before and after deposition of NPOT has been examined by scanning electron microscope (SEM). The chemical composition of NPOT has been investigated by Fourier transform infrared (FTIR), ultraviolet-visible (UV-visible) spectroscopy, and X-ray diffraction (XRD) techniques. NPOT morphology has also been examined by SEM before being deposited on the SiNWs. I-V measurements of the device have been made at room temperature under dark conditions. The heterojunction diode parameters such as turn-on voltage, reverse saturation current (I0), ideality factor (η), barrier height (ΦB) and series resistance (Rs) have been determined from the I−V curves using Schottky equations. The device shows promising characteristics as a candidate for producing heterojunction diodes.

Heterojunction of nano-poly (O-toluidine) on silicon nanowires is investigated as a candidate heterojunction diode

The organic nanostructured conducting polymer Poly (O-toluidine)/ Silicon nanowires (NPOT/SiNWs) heterojunction is investigated as a candidate heterojunction diode. For this purpose, NPOT/SiNWs heterojunction was fabricated through low cost and simple techniques. SiNWs were fabricated using improved metal-assisted electroless etching of Si substrates. NPOT thin film was chemically fabricated via in situ polymerization method. The morphology of SiNWs before and after deposition of NPOT was confirmed by scanning electron microscope (SEM). I-V measurements of the device were made at room temperature under dark conditions.

Development of a sensing device for detecting refractive index changes by using a plasmonic resonator

The authors present a sensing device for detecting refractive index changes by using a plasmonic resonator. The detection performance of the device has been numerically evaluated by the finite-difference time-domain method. The device can detect refractive index changes of 10 to the negative sixth power if a light with the wavelength of 633 nm is used as excitation source, theoretically. We have fabricated the plasmonic square resonator and evaluated it.

Thin film heterostructure based on nano-polyaniline and porous silicon

Heterojunction between n-type nanopoly-aniline and p-type porous silicon was fabricated chemically by in-situ polymerization method. Our method leads to excellent coverage of polyanilne and forming of homogenous polyaniline film upon the porous silicon wafer. The composition and morphology of the nano-polymer were confirmed by FTIR, SEM, UV-visible and TEM. Different parameters of heterojunction such as ideality factor, barrier height and series resistance values were calculated from I-V measurements at different temperature range. Ideality factor value indicated that NPANI/PSi SBD represents a non-ideal diode. The series resistance values are decreased with increasing temperature. The results also indicated that the polymerization took place throughout the porous layer.