Electrical Engineering

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Shiv Nadar University

Aluminum nitride (AlN) films were deposited on a variety of substrates (glass, Si, oxidized Si, Al-SiO2-Si, Cr-SiO2-Si, and Au-Cr-SiO2-Si) by radio frequency (RF) magnetron sputtering using an AlN target. The films were deposited without external substrate heating. The effect of RF power, ambient gas (Ar and Ar-N2) and sputtering pressure on deposition rate and crystallinity were investigated. The structure and morphology of the films were studied by X-ray diffraction, scanning electron microscopy and atomic force microscopy techniques. These investigations revealed that the AlN films prepared in mixed gas ambient (Ar-N2) were highly c-axis oriented with moderate surface roughness on all the substrate. A strong IR absorption band was observed around 670 cm- 1 which confirms the presence of Al-N bond in the film. The dc resistivity of the films was measured to be in the range of 1011 to 1012 Ω-cm at moderate electric fields. The application of these films in piezoelectric based micro-electro-mechanical systems is discussed. © 2011 Elsevier B.V. All rights reserved.

(SoE) School of Engineering

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Thin Solid Films

Deposition and characterization of c-axis oriented aluminum nitride films by radio frequency magnetron sputtering without external substrate heating

In the present work we report design, simulation, fabrication and characterization of thin film bulk acoustic resonator (FBAR). The FBAR has been modeled as a single port device with two terminals. The FBAR has been fabricated using Si-SiO2-Al-ZnO-Al structure. Zinc Oxide (ZnO) films were deposited by RF magnetron sputtering using Ceramic ZnO target in Ar-O 2 (1:1) ambient without external substrate heating. The XRD result confirms the preferred C-axis orientation of the films required for good piezoelectric properties. These ZnO films have been used to fabricate air gap type resonator. A four mask process sequence was used for this purpose. Lift-off process was used to pattern Al top electrode. In order to create the air cavity under the active device area, the bulk Si was etched in 40 % KOH at 80 °C. A specially designed mechanical jig was used to protect the front side of the device during anisotropic etching. Vector network analyzer was used to measure the reflection coefficient (S11: Return Loss) of the device. The resonant frequency of the resonator was measured to be 2.89 GHz as compare to the simulated frequency of 2.85 GHz with a return loss of 14.51 dB. © (2011) Trans Tech Publications, Switzerland.

Advanced Materials Research

Design, fabrication and characterization of ZnO based thin film bulk acoustic resonators

The paper presents a novel approach for event detection in sports videos by topic based graphical model learning. The characteristics features defining various sport events are extracted by contextual grouping of low-level video and audio features using topic modeling. Event detection is performed by learning the structure of context based distribution of characteristic features by CRF based graphical model. Experimental evaluation of the proposed concept is presented on recorded video of Handball and Soccer game. © 2011 IEEE.

Proceedings of the IEEE International Conference on Computer Vision

A hybrid framework for event detection using multi-modal features

This paper presents a MIMO two-way relaying scheme where the transceiver filter at the Relay Station (RS) processes the data using a variant of the Affine Projection Algorithm (APA), known as Partial Rank Algorithm (PRA). The relaying technique used is Amplify and Forward scheme (AF). The modulation technique used at the nodes S1 and S2 is Quadrature Phase Shift Keying (QPSK). The performance of PRA algorithm is verified by comparing its Mean-Square error performance (MSE) and Bit Error Rate (BER) with that of a transceiver filter based on Normalized Least Mean Square (NLMS) algorithm. The computational complexity of the algorithm is also tabulated. © 2011 IEEE.

2011 2nd International Conference on Wireless Communication, Vehicular Technology, Information Theory and Aerospace and Electronic Systems Technology, Wireless VITAE 2011

An Affine Projection Algorithm based transceiver filter for MIMO two-way relaying scheme

Pulsed, lock-in and frequency modulated thermography are three alternative nondestructive evaluation techniques. The defect imaging performance of these techniques are compared using: matched excitation energy; the same carbon fiber composite test piece and infrared camera system. The lock-in technique suffers from blind frequencies at which phase images for some defects disappear. It is shown that this problem can be overcome by using frequency modulated (chirp) excitation and an image fusion algorithm is presented that enhance phase imaging of defects. The signal-to-noise ratios (SNRs) of defect images obtained by the three techniques are presented. For the shallowest defects (depths 0.25 and 0.5 mm, 6 mm diameter), the pulsed technique exhibits the highest SNRs. For deeper defects the SNRs of the three techniques are similar in magnitude under matched excitation energy condition. © 2011 Elsevier Ltd.

Fulltext

NDT and E International

A comparison of the pulsed, lock-in and frequency modulated thermography nondestructive evaluation techniques

A second-breakdown phenomenon (It2) in a drain-extended n-type metaloxidesemiconductor (DENMOS) is associated with complex triggering of a parasitic bipolar transistor. Full comprehension of the problem requires 3-D modeling; however, there is even deficiency in the understanding of the phenomenon occurring in the 2-D cross-sectional plane. We present experiments and models to understand the physics of bipolar turn-on and its impact on the onset of space-charge modulation in a DENMOS device. We present a detailed analysis of the current paths involved during the bipolar turn-on. We show that a strong snapback is triggered due to coupling of the parasitic bipolar turn-on in a deeper region of the p-body and avalanche injection at the drain junction. Furthermore, we show that the ballast resistor formed in the drain region due to current crowding of electrons under high-current conditions can be modeled through a simplified 1-D analysis of the n+/n- resistive structure. © 2006 IEEE.

IEEE Transactions on Electron Devices

An insight into the ESD behavior of the nanometer-scale drain-extended NMOS device - Part I: Turn-on behavior of the parasitic bipolar

In the present work, silicon carbide (SiC) films were deposited by RF magnetron sputtering process on Si (100) substrates for micro-cantilever fabrication. The films were deposited without external substrate heating using a ceramic SiC target at 10 mTorr sputtering pressure, 200 W power and 50 mm target-to-substrate spacing. X-ray diffraction pattern shows that the films were amorphous in nature. In order to investigate the chemical inertness, the SiC coated Si substrates were dipped in buffered HF (BHF) at room temperature and in 40% KOH solution at 80 °C for varying length of time. Atomic force microscope was used to investigate surface roughness and morphology of the films before and after chemical processing. Micro-cantilever beams of the SiC film were fabricated by a single mask process. The SiC film was patterned using reactive ion etching (RIE) in SF6-O2 plasma. Thermally evaporated Al film was used as a mask during RIE process. This process also resulted in the formation of convex corners which were exploited for anisotropic etching of Si under the SiC film. The SiC cantilever beams were released by anisotropic etching of Si in KOH at 80 °C without using additional masking material. Scanning electron microscopy was used to observe the fabricated SiC micro-cantilever beams. The morphology of the SiC film after prolonged exposure to KOH was observed to be similar to that of the as-deposited film. The RF magnetron sputtered SiC films were found to be highly inert in KOH and BHF solutions. Due to difficulty in micromachining of bulk SiC material and its high cost, the RF sputtered SiC films on Si can provide a low cost structural material in MEMS. © (2011) Trans Tech Publications, Switzerland.

Fabrication of micro-cantilevers using RF magnetron sputtered silicon carbide films

We present a novel dance posture based annotation model by combining features using Multiple Kernel Learning (MKL). We have proposed a novel feature representation which represents the local texture properties of the image. The annotation model is defined in the direct acyclic graph structure using the binary MKL algorithm. The bag-of-words model is applied for image representation. The experiments have been performed on the image collection belonging to two Indian classical dances (Bharatnatyam and Odissi). The annotation model has been tested using SIFT and the proposed feature individually and by optimally combining both the features. The experiments have shown promising results. © 2011 IEEE.

Proceedings - 2011 3rd National Conference on Computer Vision, Pattern Recognition, Image Processing and Graphics, NCVPRIPG 2011

Annotating dance posture images using multi kernel feature combination

Script identification in a multi-lingual document environ- ment has numerous applications in the field of document image analysis, such as indexing and retrieval or as an initial step towards optical character recognition. In this paper, we propose a novel hierarchical framework for script identification in bi-lingual documents. The framework presents a top-down approach by performing page, block/paragraph and word level script identification in multiple stages. We utilize texture and shape based information embedded in the documents at different levels for feature extraction. The prediction task at different levels of hierarchy is performed by Support Vector Machine (SVM) and Rejection based classifier defined using AdaBoost. Experimental evaluation of the proposed concept on document collections of Hindi/English and Bangla/English scripts have shown promising results. Copyright © 2011 ACM.

ACM International Conference Proceeding Series

Script based text identification: A multi-level architecture

The stacking order and distance in columnar phases of triindole-based liquid crystals is controlled by an ethynyl linker (see picture; orange rod) between the central triindole core (green) and the peripheral flexible chains of a discotic mesogen. Hole (h) mobility is very high even if the stacking distances is not very short and the conjugated system is not particularly extended. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.