Department of Electronics (2011 - Present)
Electrical Engineering - Electronics
, University of Tehran, Iran
Electrical Engineering - Electronics
, University of Tehran, Iran
Electrical Engineering - Electronics
, University of Tehran, Iran
Research field: Designand fabrication of optophoresis systems and plasmonic tweezers, surface acousticwave (SAW) devices and acoustophoresis systems for bioparticles, components ofphotonic integrated circuits, and different kinds of sensors and detectors.
Expert:
Phone: 02182884995
Address: Electrical and Computer Engineering Faculty, 6th Block, B1 Floor
After Ph.D. in electronics- semiconductor devices, from faculty of electrical and computer engineering in university of Tehran in 2011, I continued my research program as a Post Doc. researcher in Tarbiat Modares University for one year. Then, I joined faculty of electrical and computer engineering of Tarbiat Modares University as an assistant professor, in 2012. My research interests are optophoresis systems and plasmonic tweezers, surface acoustic devices (SAW) and acoustophoresis systems, photonic integrated circuit components, and sensors and detectors.
Hereby, we introduce a tailorable coupled resonator surface acoustic waveguide (CRSAW), based on a line defect of elliptical cylinders inside a phononic crystal (PnC) of ZnO pillars over a Si substrate. The designed elliptical resonators allow emerging of a lowly dispersive, monomode shear guiding band inside the local resonance bandgap, owing to their partially broken structural symmetry in comparison with their previously reported counterparts such as pillars and hollow cylinders. Moreover, to introduce reconfigurable waveguiding behavior, we benefit from the acoustoelectric-induced elasticity modulation of ZnO, as a semiconducting piezoelectric. Switching the conductivity of ZnO structures between two limiting low and high values (0.01 S
We present the design and numerical investigation of a reconfigurable and miniature locally resonant surface acoustic wave demultiplexer based on a ZnO pillar phononic crystal, for the first time. Hollow cylinder line defects are used as waveguides, due to their good structural controllability over the local resonant waveguiding frequency and bandwidth. Two local resonant surface acoustic waveguides are designed and simulated as the output channels of the demultiplexer, and the shear-horizontal wave transmission spectra are calculated for each channel individually. The designed radio frequency demultiplexing output channels support frequencies of 4.14 GHz and 4.28 GHz, with respective bandwidths of 40 MHz and 60 MHz, while their spa
MoS2 has been well established as a promising two-dimensional candidate for optoelectronic applications, due to its unique optical and electrical properties. Here, we report fabrication of a novel heterojunction bipolar transistor (HBT) based on MoS2/Si heterojunction for the first time. Optoelectronic properties of the fabricated MoS2/Si-based HBT confirm the high-sensitivity of the device to a broad range of incident wavelengths from 380 nm to 810 nm. A Responsivity of about 400 A/W, one order of magnitude higher than the previously reported MoS2 based photodetectors, and a gain of about 1200 are obtained in response to the incident wavelength of 380 nm by the fabricated device. Our results open up a way to fabricate highly sensitive broa
Using ferroelectric domains in lead zirconate titanate (PZT: PbZr0. 3Ti0. 7O3), we propose and simulate a graphene/ferroelectric-based integrated plasmonic random access memory (P-RAM). The proposed P-RAM poses bistable behavior between two transmission levels when the polarization of the ferroelectric film is switched via tuning an applied bias. Simulation results show that when a voltage applied to a 500-nm long P-RAM is swept from− 1.5 V to+ 6 V and vice versa, the possible extinction ratio is about 18 dB. This integrated P-RAM, operating at a wavelength of 7 ?m, can be used as a memory by measuring two distinct levels of transmission. The proposed integrated memory device, also functioning as a latching plasmonic switch, does not requ
We propose ultralow-power plasmonic tweezers with no external optical source. They consist of a one-dimensional array of graphene-based plasmonic units driven by the optical transitions within the underlying array of (Al, In) As/(Ga, In) As/(Al, In) As/(Ga, In) As/(Al, In) As quantum cascaded heterostructures (QCHs), electrically biased in series. Each QCH unit formed in a nanopillar can act as a built-in optical source required for exciting the localized surface plasmons (LSPs) at the surface of the overlying circular graphene nanodisk. The stimulated emission due to intersubband transition within each optical source evanesces through the top (Al, In) As cladding layer and interacts with the overlying graphene nanodisk, inducing the LSPs r
In this study, benzene was selected as an indicator of VOCs, and a modeling procedure was carried out on benzene removal (outflow concentration of benzene, C/inflow concentration of benzene, C0), in DC and AC non-thermal plasma systems. Different diameters (18, 23, and 36?mm) of wire-tube plasma reactors were prepared, and models were raised based on the results of experiments with influencing factors of the used voltage, gap size inside the reactor, current density, and specific energy. The results showed correlation between the factors and benzene removal in both DC and AC discharge non-thermal plasma. The applied voltage as an electrical factor had negative correlation with C/C0, and the correlation was stronger than for gap size which
We are proposing next-generation lab-on-a-chip plasmonic tweezers with a built-in optical source that can be activated electrically. The building block of these tweezers is composed of an Au/p^+-InAs/p^+-AlAs_0.16Sb_0._84 Schottky diode, with a circular air-hole opened in the Au layer. Under an appropriate forward bias, the interband optical transitions in InAs, acting as a built-in optical source that can excite the localized surface plasmons (LSPs) around the edge of the hole. Numerical simulations show that the LSPs mode penetrates a chamber that is filled with water and electrically isolated from the top gold layer, providing the gradient force components desired for trapping the target nanoparticles suspended in the water. Moreover, we
This paper demonstrates far field, trapping of a single dielectric nanoparticle using a Plasmonic Zone Plate Lens. This is achieved by beaming a linearly polarized light through series of concentric annular slit-rings formed in Gold, leading to creation of a sub-diffraction focal spot in the far field which can be used as a hotspot to trap the nanoparticle in it, suspended. A stable trap is formed in the far field using this structure and a 100-nm Polystyrene particle is successfully trapped using this technique. Forces are calculated in both x and z directions and the stability of the trap is further proved by calculating the potential well for x and z directions at location of the focal spot.
Recently, the emerging field of two-dimensional materials is known to be promising due to their unique structure, special optical and electrical properties, and their applications in optoelectronic devices. In this paper, for the first time, we are reporting on new MoS 2 samples with slightly different structures to that of the conventional ones. This is achieved using chemical vapor deposition (CVD) method and further changing of argon flux, furnace temperature, and precursors' distance to the location of substrates. This structure is sword-like, and it should be noted that length of some of these sword-like specimens is measured to be ≅700 micrometres. The broad dimensions of these samples may simplify the manufacturing process of the
In this report, gold cauldrons are proposed and proved as efficient candidates for plasmonic tweezers. Gold cauldrons benefit from high field localization in the vicinity of their apertures, leading to particle trapping by a reasonably low power source. The plasmonic trapping capability of a single gold cauldron and a cauldrons cluster are studied by investigating the plasmon-induced variations of the optical trap stiffness in a conventional optical tweezers configuration. This study shows that the localized plasmonic fields and the consequent plasmonic forces lead to enhanced trap stiffness in the vicinity of the cauldrons. This observation is pronounced for the cauldrons cluster, due to the additive plasmonic fields of the neighboring cau
In this paper a Surface Acoustic Wave (SAW) device with the wavelength of is proposed. Inter Digital Transducers (IDTs) of the device are fabricated through the photolithography method. (BA) 2 PbI 4 , a quasi 2D Ruddlesden Popper Perovskite (RPP), is used as piezoelectric material on the top of IDTs. The RF measurements of the SAW device are investigated and the resonance frequencies at 71.43 MHz and 289.83 MHz show the accurate matching of transmission (S21) and reflection (S11) spectrums.
In this paper a humidity sensor based on MoS 2 sheets is presented. MoS 2 sheets are synthesized on Si/SiO 2 substrate using chemical vapor deposition (CVD) method. Shadow mask is utilized in order to deposit Nickel on MoS 2 sheets, resulting in formation of a Nickel-MoS 2 -Nickel, which acts as a Metal-Semiconductor-Metal (MSM) structure. Resistive transduction technique is used as the sensitivity analysis and a 494% sensitivity is achieved for 55% relative humidity (RH). Furthermore, response time and recovery time of the proposed device are 10s and 53s, respectively.
Two dimensional Ruddlesden Popper Perovskite (RPP) has attracted optoelectronic research groups in recent years because of their photoabsorption coefficient as high as 3D counter parts while they are much more stable and durable. In this work, a metal-semiconductor-metal photodetector was fabricated. The metals were aluminum and the semiconductor was (BA) 2 PbI 4 . Photoresponsivity and detectivity of this device were 2.16mA/W and 1.6 ? 10 9 jones respectively. Its fall time and rise time were 1.25 and 3 ms. The results showed that this device can be used in fast visible light communication (VLC) systems.
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