http://dspace.dtu.ac.in:8080/jspui/handle/123456789/13 2026-07-13T08:54:36Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/23030 Title: TCAD-BASED MAGNETIC ANALYSIS OF 2D-MagFinFET IN ORTHOGONAL DIRECTIONS FOR MEDICAL MICR0-ROBOTS APPLICATION Authors: AMAN; Chaujar, Rishu (SUPERVISOR) Abstract: The need for magnetic sensor is aggressively increasing in medical area to navigate the medical micro-robots through the blood vessels to target. This dissertation presents a detailed TCAD based investigation of novel Two Directional Magnetic Fin Field Effect Transistor (2D-MagFinFET) magnetic sensor based on the advanced 3D architecture of Field Effect Transistor. The proposed device is designed to overcome the limitation of traditional magnetic sensor to only sense the single direction magnetic field. The proposed device is designed to sense orthogonal magnetic field in Y and Z direction. It is operated on concept of Lorentz force act on charge carrier in channel when external magnetic field applied which deflect the carrier from their path which governs differential current (∆ID). Device uses two parallel fins to sense the magnetic field. One fin will detect the magnetic field of Y-direction and other one of Z-direction without any coupling of relative sensitivity. Two layers of SiO2/HfO2 as gate dielectric is used to enhance the overall performance of the proposed device. The performance of the proposed device is analyzed in terms of SS, VTH, ION, IOFF, DIBL, SR, magnetic sensitivity (SA) and Relative magnetic sensitivity (SR). The proposed device demonstrates a SS of 59.96 mV/dec which is improved by 4.83% in contrast to existing devices. The VTH of device is increased from 0.21 V to 0.48 V by 128.57% which help to protect the sensor to turn on accidently. IOFF and ION currents of the proposed device is 5.24 fA and 12.9 µA having SR of 2.39 × 109. The proposed device has a DIBL of 8.24 mV/V at gate length of 50 nm show how efficiently device overcome the problem of short channel effect. These results demonstrate the better switching and performance of proposed device than the existing device. The magnetic response shows the linear dependency of differential current (∆IY and ∆IZ) with Magnetic field having a sensitivity of 159.27 nA/T in Y-direction and 147.13 nA/T in Z-direction at 100 µA biased current. The relative sensitivity is 0.00159 T-1 and 0.00147 T-1 in Y and Z direction respectively, improved from recently reported device. Owing the magnetic sensitivity in orthogonal direction the proposed device is suitable for the spatial tracking and navigation of medical micro-robots. 2026-05-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22958 Title: ANALYSIS OF SELF-FOCUSING OF LASER BEAMS IN QUANTUM PLASMA Authors: SINHA, ANCHIT; Sharma, Suresh C. (SUPERVISOR) Abstract: The relativistic self-focusing of laser beams in quantum plasma has drawn considerable inter est because of its applications in inertial confinement fusion, charged-particle acceleration, and high-energy-density physics. In this dissertation, we study the propagation and self-focusing of non-conventional beam profiles, namely Bessel-Gaussian and Elliptical-Gaussian beams, in magnetized quantum plasmas with spatial density gradients. The paper considers combinations of beam geometry, magnetic fields and plasma inhomogeneity which have never been system atically treated in previous work. The study uses the quantum hydrodynamic (QHD) model, incorporating the Bohm potential, exchange-correlation effects, relativistic ponderomotive forces, and the influence of an exter nal magnetic field. Applying the paraxial approximation and the Wentzel–Kramers–Brillouin (WKB) method reduces Maxwell’s equations to a differential equation governing beam-width evolution along the propagation axis. For Paper-1 on Bessel-Gaussian beams, this results in a second-order nonlinear ordinary differential equation, solved numerically using the fourth-order Runge-Kutta method. Simulations are carried out for high laser frequencies of (1.78×1020s−1), electron densities of (n0 = 4 × 1019cm−3) satisfying (χ ≥ 1), an axial magnetic field of (ωc/ω = 0.3), and exponential density ramp parameters (d = 5,10,20). Key findings from Paper-1 show that: (1) thermal quantum plasma enables much stronger and more sustained self-focusing than classical and cold quantum plasmas; (2) exponential den sity ramps greatly accelerate self-focusing, maintaining high intensity over multiple Rayleigh lengths; (3) Bessel-Gaussian beams outperform Gaussian beamsbecauseoftheirring-shaped in tensity profile; (4) the transverse wave parameter µ significantly enhances self-focusing; and (5) beyond a threshold, increasing laser intensity reduces self-focusing due to relativistic mass satu ration and exchange-correlation effects introducing competingnonlinearities. Paper-2(Elliptical Gaussian beams in magnetized quantum plasma with tangential densityramps)isinanadvanced stage with mathematical framework and numerical analysis under way. 2026-05-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22954 Title: KINECTICS OF PROTEIN- AGGREGATION AND SELF ASSEMBLY Authors: AMISHI; Bohidar, Himadri B (SUPERVISOR) Abstract: The process of protein aggregation is a vital one which depends on time and necessitates models which transcend closed-system approaches to become models of dynamic kinetics and proteostasis. The generalized modelling approach connects the physical mechanism of aggregation with the biological system of aging. This physical model is composed of kinetic laws, the behaviours of the source terms (monomer generation/elimination), and thermos- reversible assembly. The model predicts the scaling behaviours of aggregation which depend on whether the process is limited by the formation of aggregates or the generation of monomers. The biological aspect of the modelling framework takes into account the effect of the decline in the process of proteostasis in a systems biology model. Coupled differential equations form the basis of this biological model with consideration of the decline in physiological function, hormone regulation, genetic instability, and gender-related effects. Importantly, the non-linear dynamics of proteostasis with respect to age-related stresses and inefficient clearing must be accounted for since they can lead to a tipping point where a rapid build-up occurs. 2026-05-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22880 Title: DEVELOPMENT OF 2D MOLYBDENUM DISULFIDE BASED NO2 GAS SENSOR Authors: KUMAR, RAMESH; SINGH, VINOD ( SUPERVISOR ); KUMAR, MAHESH ( CO- SUPERVISOR) Abstract: The rapid increase in environmental pollution and industrial activities has led to a growing demand for efficient, reliable, and cost-effective gas sensing technologies. Toxic gases such as nitrogen dioxide (NO₂) and hydrogen (H₂) pose significant risks to human health, environmental safety, and industrial operations. In this context, the present thesis focuses on the development and investigation of nanostructured molybdenum disulfide (MoS₂) thin films for gas sensing applications, with particular emphasis on understanding their structural properties and sensing behavior toward NO₂ and H₂ gases. The research begins with the synthesis of MoS₂ thin films using a combination of electron beam evaporation and chemical vapor deposition (CVD) techniques. Molybdenum (Mo) thin films of varying thicknesses were initially deposited on suitable substrates and subsequently sulfurized under controlled conditions to obtain high-quality MoS₂ layers. Systematic optimization of synthesis parameters such as film thickness, annealing temperature, and sulfurization temperature was carried out to achieve uniform, crystalline, and reproducible thin films. Among the different samples studied, the 20 nm thick MoS₂ films exhibited superior crystallinity, structural stability, and surface uniformity, making them suitable for gas sensing applications. Comprehensive structural and morphological characterization was performed using X ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM). The XRD analysis confirmed the formation of polycrystalline hexagonal-phase MoS₂, while Raman studies validated the presence of characteristic vibrational modes corresponding to in plane and out-of-plane lattice vibrations. Surface morphology analysis revealed the formation of nanosheet and flower-like structures, providing a high surface-to-volume ratio and abundant active sites for gas adsorption. A significant contribution of this work is the investigation of MoS₂–hydrogen interaction using in-situ X-ray diffraction. This approach enabled real-time monitoring of structural changes in MoS₂ under controlled hydrogen gas environments, eliminating sample-to-sample variations. The study revealed that exposure to hydrogen gas leads to noticeable changes in diffraction peak intensity, indicating structural modifications and possible lattice strain effects. These findings provide deeper insights into the interaction mechanisms between hydrogen molecules and layered MoS₂ structures. Furthermore, the gas sensing performance of MoS₂ thin films toward NO₂ gas was systematically investigated as a function of operating temperature and gas concentration. The fabricated sensor exhibited n-type semiconducting behavior, with an increase in electrical resistance upon exposure to the oxidizing NO₂ gas due to electron withdrawal. The sensing response improved significantly with increasing temperature, achieving optimal performance at 150 °C. The sensor demonstrated a RAMESH KUMAR ix maximum response of approximately 14.2% at 20 ppm concentration, along with a response time of about 102 seconds and a recovery time of 94 seconds. Additionally, the sensor response increased with increasing NO₂ concentration, indicating strong adsorption and efficient charge transfer processes. Despite the promising performance, certain limitations such as reduced recovery at higher gas concentrations and potential structural defects were observed. These findings highlight the need for further improvements in selectivity, stability, and environmental adaptability of MoS₂-based sensors. Overall, this thesis establishes a strong correlation between synthesis conditions, structural properties, and gas sensing performance of MoS₂ thin films. The integration of advanced synthesis techniques with in-situ characterization provides a comprehensive understanding of gas–material interactions. The results demonstrate that nanostructured MoS₂ is a highly promising material for next-generation gas sensors, with potential applications in environmental monitoring, industrial safety, and clean energy systems. 2026-05-01T00:00:00Z