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V. Ramgopal Rao

Bio: V. Ramgopal Rao is an academic researcher from Indian Institute of Technology Bombay. The author has contributed to research in topics: MOSFET & Gate dielectric. The author has an hindex of 26, co-authored 270 publications receiving 2751 citations. Previous affiliations of V. Ramgopal Rao include Bundeswehr University Munich & IITB-Monash Research Academy.


Papers
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Journal ArticleDOI
TL;DR: The ability of the sensor in detecting TNT vapour concentration down to less than six parts per billion with a sensitivity of 1 mV/ppb and the noise characterization results support their suitability for biochemical sensing applications.
Abstract: This paper reports an optimized and highly sensitive piezoresistive SU-8 nanocomposite microcantilever sensor and its application for detection of explosives in vapour phase. The optimization has been in improving its electrical, mechanical and transduction characteristics. We have achieved a better dispersion of carbon black (CB) in the SU-8/CB nanocomposite piezoresistor and arrived at an optimal range of 8?9?vol% CB concentration by performing a systematic mechanical and electrical characterization of polymer nanocomposites. Mechanical characterization of SU-8/CB nanocomposite thin films was performed using the nanoindentation technique with an appropriate substrate effect analysis. Piezoresistive microcantilevers having an optimum carbon black concentration were fabricated using a design aimed at surface stress measurements with reduced fabrication process complexity. The optimal range of 8?9?vol% CB concentration has resulted in an improved sensitivity, low device variability and low noise level. The resonant frequency and spring constant of the microcantilever were found to be 22?kHz and 0.4? N?m ? 1 respectively. The devices exhibited a surface stress sensitivity of 7.6?ppm (mN?m ? 1) ? 1 and the noise characterization results support their suitability for biochemical sensing applications. This paper also reports the ability of the sensor in detecting TNT vapour concentration down to less than six parts per billion with a sensitivity of 1? mV/ppb.

103 citations

Journal ArticleDOI
TL;DR: In this article, a design space comprising of I_ON, a drain saturation voltage, and a drain threshold voltage for minimizing the propagation delay of circuits using TFETs is presented. But, as shown in this paper, the delay of the circuit is determined by the rise/fall time rather than by propagation delay.
Abstract: Improving the on-current has been the focus of enhancing the performance of tunnel field-effect transistors (TFETs). In this paper, we show that the increase in I_ON is not sufficient to improve the circuit performance with TFETs. As TFETs show a drain-barrier voltage in their output characteristics below which the drain current drastically reduces, the rise/fall time significantly increases. This reduces the dynamic noise margin and limits the performance achievable from TFETs. We show that, in TFETs, the delay of the circuit is determined by the rise/fall time rather than by the propagation delay. The saturation voltage is much higher compared with that of complementary metal-oxide-semiconductor (CMOS) devices, leading to a lower gain and a lower static noise margin in digital circuits, as well as impeding the performance of latch/regenerative circuits. We present a design space comprising of I_ON, a drain saturation voltage, and a drain threshold voltage for minimizing the propagation delay of circuits using TFETs. Finally, for the same off-current and speed of operation, TFET devices tend to suffer from a higher gate capacitance compared with CMOS devices. If this behavior is not taken into account during the circuit design, these devices (although designed for low-power applications) can dissipate more power at the same speed of operation than CMOS counterparts.

102 citations

Journal ArticleDOI
TL;DR: In this article, a piezoresistive polymer nano-composite microcantilever sensor platform for the detection of 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-triazine (RDX) and pentaerythritol tetranitrate (PETN) vapors at room temperature was demonstrated.
Abstract: In the present paper, we demonstrate a compact, nonoptical, and inexpensive polymer nano-composite microcantilever sensor platform for the detection of 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-triazine (RDX) and pentaerythritol tetranitrate (PETN) vapors at room temperature. In order to achieve sufficient selectivity, the piezoresistive polymer nano-composite microcantilevers coated with gold surfaces are modified with self-assembled monolayers (SAM) of 4-mercaptobenzoic acid (4-MBA), 6-mercaptonicotonic acid (6-MNA) and 2-mercaptonicotonic acid (2-MNA). The SAMs formation is confirmed by FTIR and contact angle measurements. The ultrahigh sensitive piezoresistive polymer nano-composite microcantilever provides detection sensitivities in the below parts-per-trillion level within few seconds of exposure under ambient conditions. Maximum bending of the microcantilever is achieved within 20 s with response and recovery time of ∼3 s and 4 s, respectively. The cross selectivity of 4-MBA and 6-MNA coated microcantilevers is confirmed by investigating exposure to different organic compounds. We also demonstrate that the polymer nano-composite microcantilever is ideally suited for “electronic nose” applications. Further, the ultra-high sensitivity and low cost of polymer nano-composite microcantilever can lead to the development of a rugged portable, handheld device for rapid and sensitive detection of explosive vapors.

75 citations

Journal ArticleDOI
TL;DR: In this article, the epoxy groups on the SU-8 surface were hydrolyzed in the presence of sulphochromic solution, and the surface was treated with [3-(2-aminoethyl) aminopropyl]-trimethoxysilane (AEAPS).

74 citations

Journal ArticleDOI
TL;DR: In this paper, the authors developed circuit models for the parasitic capacitances in conventional and high-K gate dielectric MOS transistors by taking into account the presence of source/drain contact plugs.
Abstract: In deep submicrometer MOSFETs the device performance is limited by the parasitic capacitance and resistance. Hence a circuit model is needed to treat these effects correctly. In this work, we have developed circuit models for the parasitic capacitances in conventional and high-K gate dielectric MOS transistors by taking into account the presence of source/drain contact plugs. The accuracy of the model is tested by comparing the modeled results with the results obtained from three-dimensional (3-D) Monte-Carlo simulations and two-dimensional (2-D) device simulations over a wide range of channel length and oxide thickness. The model is also used to study the dependence of parasitic capacitance on gate length, gate electrode thickness, gate oxide thickness, gate dielectric constant, and spacer width.

73 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the authors discuss sensors with transducers in a form of cantilevers, which are especially attractive as transducers for chemical and biological sensors, and provide a brief analysis of historical predecessors of the modern cantilever sensors.
Abstract: Since the late 1980s there have been spectacular developments in micromechanical or microelectro-mechanical (MEMS) systems which have enabled the exploration of transduction modes that involve mechanical energy and are based primarily on mechanical phenomena. As a result an innovative family of chemical and biological sensors has emerged. In this article, we discuss sensors with transducers in a form of cantilevers. While MEMS represents a diverse family of designs, devices with simple cantilever configurations are especially attractive as transducers for chemical and biological sensors. The review deals with four important aspects of cantilever transducers: (i) operation principles and models; (ii) microfabrication; (iii) figures of merit; and (iv) applications of cantilever sensors. We also provide a brief analysis of historical predecessors of the modern cantilever sensors.

1,165 citations

01 Jan 2016
TL;DR: The design of analog cmos integrated circuits is universally compatible with any devices to read and is available in the book collection an online access to it is set as public so you can download it instantly.
Abstract: Thank you very much for downloading design of analog cmos integrated circuits. Maybe you have knowledge that, people have look hundreds times for their favorite novels like this design of analog cmos integrated circuits, but end up in malicious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they cope with some malicious virus inside their laptop. design of analog cmos integrated circuits is available in our book collection an online access to it is set as public so you can download it instantly. Our digital library saves in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Merely said, the design of analog cmos integrated circuits is universally compatible with any devices to read.

912 citations

Journal ArticleDOI
TL;DR: This review highlights the research aimed at the implementation of MOFs as an integral part of solid-state microelectronics and discusses the fundamental and applied aspects of this two-pronged approach.
Abstract: Metal-organic frameworks (MOFs) are typically highlighted for their potential application in gas storage, separations and catalysis. In contrast, the unique prospects these porous and crystalline materials offer for application in electronic devices, although actively developed, are often underexposed. This review highlights the research aimed at the implementation of MOFs as an integral part of solid-state microelectronics. Manufacturing these devices will critically depend on the compatibility of MOFs with existing fabrication protocols and predominant standards. Therefore, it is important to focus in parallel on a fundamental understanding of the distinguishing properties of MOFs and eliminating fabrication-related obstacles for integration. The latter implies a shift from the microcrystalline powder synthesis in chemistry labs, towards film deposition and processing in a cleanroom environment. Both the fundamental and applied aspects of this two-pronged approach are discussed. Critical directions for future research are proposed in an updated high-level roadmap to stimulate the next steps towards MOF-based microelectronics within the community.

908 citations

Journal ArticleDOI
TL;DR: A wide range of fluorescent materials, such as conjugated polymers, small fluorophores, supramolecular systems, bio-inspired materials and aggregation induced emission-active materials, and their sensing performance and sensing mechanism are the centerpiece of this review.
Abstract: The detection of explosives is one of the current pressing concerns in global security. In the past few decades, a large number of emissive sensing materials have been developed for the detection of explosives in vapor, solution, and solid states through fluorescence methods. In recent years, great efforts have been devoted to develop new fluorescent materials with various sensing mechanisms for detecting explosives in order to achieve super-sensitivity, ultra-selectivity, as well as fast response time. This review article starts with a brief introduction on various sensing mechanisms for fluorescence based explosive detection, and then summarizes in an exhaustive and systematic way the state-of-the-art of fluorescent materials for explosive detection with a focus on the research in the recent 5 years. A wide range of fluorescent materials, such as conjugated polymers, small fluorophores, supramolecular systems, bio-inspired materials and aggregation induced emission-active materials, and their sensing performance and sensing mechanism are the centerpiece of this review. Finally, conclusions and future outlook are presented and discussed.

867 citations

Journal ArticleDOI
TL;DR: An overview of piezoelectric polymers based on their operating principle is given in this paper, which includes three main categories: bulk polymers, piezocomposites and voided charged polymers.
Abstract: Polymer based MEMS and microfluidic devices have the advantages of mechanical flexibility, lower fabrication cost and faster processing over silicon based ones. Also, many polymer materials are considered biocompatible and can be used in biological applications. A valuable class of polymers for microfabricated devices is piezoelectric functional polymers. In addition to the normal advantages of polymers, piezoelectric polymers can be directly used as an active material in different transduction applications. This paper gives an overview of piezoelectric polymers based on their operating principle. This includes three main categories: bulk piezoelectric polymers, piezocomposites and voided charged polymers. State-of-the-art piezopolymers of each category are presented with a focus on fabrication techniques and material properties. A comparison between the different piezoelectric polymers and common inorganic piezoelectric materials (PZT, ZnO, AlN and PMN?PT) is also provided in terms of piezoelectric properties. The use of piezopolymers in different electromechanical devices is also presented. This includes tactile sensors, energy harvesters, acoustic transducers and inertial sensors.

778 citations