Department of Electrical Engineering

Indian Institute of Technology Hyderabad (IITH) is a premier institute of science and technology established in 2008. IITH has been consistently ranked in the&nbsp;<a href="https://iith.ac.in/reports/" rel="noopener noreferrer">top 10 institutes</a>&nbsp;in India for Engineering&nbsp;<a href="https://www.nirfindia.org/2021/EngineeringRanking.html" rel="noopener noreferrer" target="_blank">according to NIRF</a>&nbsp;making it one of the most coveted schools for science and technology in the country.

IITH offers&nbsp;<a href="https://iith.ac.in/academics/under-graduate/">undergraduate programs</a>&nbsp;in all the classical engineering disciplines, applied sciences, design, as well as several modern interdisciplinary areas. Students are given a flexibility to explore a broad set of areas, and potentially pursue a minor or double major in a discipline that is not their own. Students who wish to seek a deeper understanding of their own discipline are strongly encouraged to get involved in cutting-edge research with the help of a faculty to mentor them, and earn an Honors in their own field.

The very foundation of IIT Hyderabad is based on&nbsp;<a href="https://iith.ac.in/research/">research and innovation</a>. The vibrant research culture is evident from the number of patents and publications that IITH produces consistently every year. IITH offers&nbsp;<a href="https://iith.ac.in/academics/programmes-offered/">graduate programs</a>&nbsp;at both a masters, and a doctoral level, in several diverse areas. There are separate programs for technology, design, science, and liberal arts. The&nbsp;<a href="https://iith.ac.in/academics/post-graduate/">MTech program</a>&nbsp;is offered in various modes and durations to cater to the ever-growing need of postgraduate level professionals in the country.

IITH encourages and supports&nbsp;<a href="https://iic-iith.netlify.app/index.html" rel="noopener noreferrer" target="_blank">innovation and entrepreneurship</a>&nbsp;at every stage. The minor program in entrepreneurship is open to all students of IITH, and many of the courses are offered by industrialists who are entrepreneurs themselves. There are various&nbsp;<a href="https://iith.ac.in/research/centres-incubators/">innovation centers and incubators</a>&nbsp;that promote entrepreneurship and help mentor young innovators. IITH has been very successful in building tie-ups with leading academic institutions around the globe.

IITH enjoys a very special relationship with Japanese universities and industries that goes beyond academic and research collaborations. In fact, some of the iconic buildings in IITH campus will carry the signature of Japanese architecture.

IITH creates a unique holistic ecosystem for education that offers interactive learning, a very flexible academic structure, cutting-edge research, strong industry collaboration, and entrepreneurship. This is an environment which enables students and faculty to translate their dreams into realities.

IIT Hyderabad

The mixing characteristics in spiral microhannels are studied experimentally and numerically in this work. Effect of cross section aspect ratio (α = 0.3–1.2) on mixing characteristic is studied both qualitatively and quantitatively using top as well as side view details. The study is carried out for a wide range of Reynolds number (1–468) and Dean number (0.1–75). The pathline behavior and species fraction are tracked to understand the effect of Reynolds number and aspect ratio on mixing. It is observed that spiral microchannel with higher aspect ratio results in better mixing as compared to smaller aspect ratio microchannel. An optimal Reynolds number at which the mixing efficiency is maximized is observed from the experimental data. It is observed that the fluid is trapped within the vortex core at higher Reynolds number, leading to a reduction in mixing efficiency and appearance of a maxima. Frequent twisting of pathlines is further identified to affect mixing and leads to a dependence of mixing on aspect ratio. The analysis presented in this work is of significance in the design of spiral microchannel based microreactors. © 2017 Elsevier Inc.

World University root node

Experimental Thermal and Fluid Science

Mixing in planar spiral microchannel

Second order harmonic generation due to nonlinear propagation of whistler pulse through high density quantum plasma. The plasma is magnetized by applying a transverse static magnetic field. The interaction formulation has been developed using quantum hydrodynamic (QHD) model. The effect of quantum Bohm potential, Fermi pressure and electron-1/2 spin have been taken into account. The perturbed particle trajectory, particle density, spin magnetic moment has been setup. The field amplitude of harmonic radiation has been studied with reference to the fundamental amplitude of the incident whistler radiation. © 2017 Author(s).

AIP Conference Proceedings

Second harmonic generation by whistler pulse in magnetized quantum plasma

We present a new model for surface roughness (SR) scattering in n-type multi-gate FETs (MuGFETs) and gate-all-around nanowire FETs with fairly arbitrary cross-sections, its implementation in a complete device simulator, and the validation against experimental electron mobility data. The model describes the SR scattering matrix elements as non-linear transformations of interface fluctuations, which strongly influences the root mean square value of the roughness required to reproduce experimental mobility data. Mobility simulations are performed via the deterministic solution of the Boltzmann transport equation for a 1D-electron gas and including the most relevant scattering mechanisms for electronic transport, such as acoustic, polar, and non-polar optical phonon scattering, Coulomb scattering, and SR scattering. Simulation results show the importance of accounting for arbitrary cross-sections and biasing conditions when compared to experimental data. We also discuss how mobility is affected by the shape of the cross-section as well as by its area in gate-all-around and tri-gate MuGFETs. © 2017 Author(s).

Fulltext

Journal of Applied Physics

Improved surface-roughness scattering and mobility models for multi-gate FETs with arbitrary cross-section and biasing scheme

Air-stable and area-selective doping strategies have eluded 2D materials and thus been a major bottleneck in realizing the plethora of semiconductor devices which require an built in electric field accessible from a p/n junction. Here, we demonstrate the possibility of p-doping through Vacancy Engineering, which unlike previous reports of molecular/substitutional doping is both area/dopant controllable and air-stable. Through Ar+ ions of appropriate energy and fluence bombarded on exfoliated MoS2, we demonstrate creation of sulfur vacancies that vary the S:Mo stoichiometry from 1.94 to 0.97 and hence controllably introduce p-type doping as verified using in-situ XPS and ex-situ Raman/PL measurements. FETs fabricated on Ar+ bombarded flakes show complete flip in polarity of carrier type from n-type to p-type when compared to Reference samples with the same metal contacts. Furthermore, selective Ar+ Bombardment only on contacts region shows effective hole injection with Ion/Ioff&gt;103. Finally p/n junctions with Ar+ bombardment performed on one half of the flake demonstrate high rectification ratio (&gt;104), forward currents (∼0.6 mA/cm2) and excellent photoresponse (Ilight/Idark ∼103) and responsivity (100-400 μA/W). © 2017 IEEE.

Device Research Conference - Conference Digest, DRC

Realizing P-FETs and photodiodes on MoS2 through area-selective p-doping via vacancy engineering

Vector-controlled induction motor drives are quite popular in the industry in applications that demand high dynamic performance. This paper describes the implementation of a complete industrial vector-controlled drive for a 30 kW induction motor. The control algorithms for the drive are implemented using a TMS320F28335 Digital Signal Controller (DSC). Various monitoring and protection functions for the drive are implemented using a Cyclone IV FPGA that communicates with the DSC, and acts as the master controller for the drive. The FPGA also communicates with a Human–Machine Interface to provide a simple graphical control interface to the operator. © 2017, Indian Academy of Sciences.

Sadhana - Academy Proceedings in Engineering Sciences

Design and implementation of an industrial vector-controlled induction motor drive

In the present scenario, high power industrial drive applications mostly employ Voltage Source Inverter (VSI) fed induction motors. In the very high power ranges (>10 MW), Load Commutated Inverter (LCI) fed synchronous motors are also used. Economy and efficiency are crucial factors for drives in such high power applications. Recently, a new hybrid drive topology using a specially designed dual stator winding induction machine fed from an LCI and a VSI has been proposed. The machine has been named as the Active-Reactive Induction Machine (ARIM). The use of a thyristor-based LCI to handle all the active power, is expected to make the ARIM drive a much more efficient and economic option than the VSI based drives. This paper presents a quantitative evaluation of the efficiency and economic benefits of the ARIM topology employed in a 1 MW drive application, as compared to three other popular drive topologies used in this power range. These are: (a) A low voltage VSI based drive, (b) A medium voltage two level VSI based drive, and (c) A medium voltage three level VSI fed drive. The losses and efficiency in each case are compared by simulation studies using MATLABIPLECS. Further, an estimate of the approximate costs of the drive topologies is made to compare their economic benefits. It is found that the ARIM drive has major benefits in cost and efficiency, when compared to other conventional drives. ©2016 IEEE.

IEEE International Conference on Power Electronics, Drives and Energy Systems, PEDES 2016

A quantitative evaluation of the efficiency and economic benefits of the active-reactive induction machine drive in high power applications

Flexible broadband photodetectors based on 2D MoS2 have gained significant attention due to their superior light absorption and increased light sensitivity. However, pristine MoS2 has absorption only in visible and near IR spectrum. This paper reports a paper-based broadband photodetector having ZnS–MoS2 hybrids as active sensing material fabricated using a simple, cost effective two-step hydrothermal method wherein trilayer MoS2 is grown on cellulose paper followed by the growth of ZnS on MoS2. Optimization in terms of process parameters is done to yield uniform trilayer MoS2 on cellulose paper. UV sensing property of ZnS and broadband absorption of MoS2 in visible and IR, broadens the range from UV to near IR. ZnS plays the dual role for absorption in UV and in the generation of local electric fields, thereby increasing the sensitivity of the sensor. The fabricated photodetector exhibits a higher responsivity toward the visible light when compared to UV and IR light. Detailed studies in terms of energy band diagram are presented to understand the charge transport mechanism. This represents the first demonstration of a paper-based flexible broadband photodetector with excellent photoresponsivity and high bending capability that can be used for wearable electronics, flexible security, and surveillance systems, etc. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Advanced Functional Materials

Large-Area, Flexible Broadband Photodetector Based on ZnS–MoS2 Hybrid on Paper Substrate

Graphene due to its unique physicochemical properties mainly its large surface to volume ratio, excellent thermal and electrical conductivity, biocompatibility, as well as broad electrochemical potential, has received considerable attention for biosensing applications. In this review paper, we provide a comprehensive overview of the recent advances in the field of electrochemical biosensors developed using the graphene nanomaterial including graphene oxide, reduced graphene oxide, CVD graphene, and various graphene based nanostructures including nanomesh, nanowalls, etc. in healthcare related applications. The review focusses on material synthesis, device fabrication, and biofunctionalization of graphene electrodes in biosensing such as those based on electrochemical impedance, amperometry/voltammetry, potentiometry, conductometry, and field effect transistor. Additionally, several ingenious biosensing strategies of graphene biosensor in clinical diagnosis for detection of proteins (disease biomarkers), nucleic acids (mutation analysis in genetic diseases), small molecules (disease metabolites like glucose, lactic acid etc.), and pathogens (bacterial and viral infections) have also been discussed. © 2017 Materials Research Society.

Journal of Materials Research

Graphene based biosensors for healthcare

In this work, we demonstrate for the first time, a solution-processed MoS2 (n)-CuO (p) piezotronic diode on a flexible paper substrate for an enhanced broadband photodetector and active analog frequency modulator by application of external mechanical strain. There are no reports on solution-processed large area fabrication of MoS2-based heterojunctions wherein the external mechanical strain modulates the transport properties at the device level which can be further utilized at the circuit level for frequency modulation. When external strain is applied, because of the non-centrosymmetric structure of MoS2, the piezopotential induced adjusts the band structure at the junction and broadens the depletion region, which decreases the depletion capacitance of the diode. The widening of the depletion region improves the separation of photo-generated carriers and enhances the performance of the diode under both visible and NIR illumination. The fabricated piezotronic diode exhibited higher responsivity towards visible light illumination when compared to NIR illumination. The responsivity of the fabricated piezotronic diode increased by 69.7% under 2% strain. Such a versatile technique for fabrication of a diode and its utilization at both the device and circuit levels is a major step ahead in flexible and wearable electronics with applications ranging from digital, to analog, and optoelectronics. © 2017 The Royal Society of Chemistry.

Journal of Materials Chemistry C

Fabrication of a solution-processed, highly flexible few layer MoS2 (n)-CuO (p) piezotronic diode on a paper substrate for an active analog frequency modulator and enhanced broadband photodetector

Herein, we report the fabrication of ZnS-MoS2 hybrids on cellulose paper using two step solution processed hydrothermal method wherein MoS2 was grown on paper substrate followed by the growth of ZnS. The as fabricated structure was characterized using Raman spectroscopy, which confirmed the growth of trilayer MoS2-ZnS. 20.6% and 15.7% decrease in resistance was observed on illumination with UV light and IR light, respectively. The strategy presented here provides a simple, low-cost approach for fabrication of efficient broadband photodetector which finds potential applications in security and surveillance and is a step ahead in large area flexible electronics applications. © 2017 IEEE.