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Nandita DasGupta
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Nandita DasGupta
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Nandita DasGupta
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DasGupta, N.
Basu, Nandita
Basu, N.
Dasgupta, N.
DasGupta, Nandita
Gupta, Nandita Das
Dasgupta, Nandita
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93 results
Now showing 1 - 10 of 93
- PublicationA unified model for gate capacitance-voltage characteristics and extraction of parameters of Si/SiGe heterostructure pMOSFETs(01-08-2007)
;Bindu, B.; A unified model for gate capacitance-voltage characteristics of Si/SiGe heterostructure pMOSFETs is presented. This model is applicable to buried-channel, surface-channel, and dual-channel Si/SiGe heterostructure pMOSFETs. The results from the model are compared with the experimental results and are found to be in excellent agreement. A simple and accurate method for the extraction of parameters such as the valence band offset, Si cap layer thickness, threshold voltages, and substrate doping is also presented in this paper. © 2007 IEEE. - PublicationEvidence of Fowler-Nordheim tunneling in gate leakage current of AlGaN/GaN HEMTs at room temperature(01-12-2014)
;Turuvekere, Sreenidhi ;Rawal, Dipendra Singh; Dependence of gate leakage current on Al mole fraction of AlGaN/GaN high-electron mobility transistors (HEMTs) is studied using temperature-dependent current-voltage and capacitance-voltage characteristics. The reverse leakage current is mostly dominated by Poole-Frenkel (PF) emission in the structures used in this brief. However, it is observed that at higher mole fractions, due to higher electric field across the barrier, Fowler-Nordheim (FN) tunneling also contributes to the gate leakage current even at room temperature and above. An expression for critical temperature below which FN tunneling component becomes comparable with or more than PF emission component is presented. It is concluded that the dominant gate leakage mechanisms in III - N HEMTs are dependent on mole fraction of the barrier material and the temperature. However, the relative strengths of PF emission and FN tunneling are also influenced by various process-dependent parameters. - PublicationEffect of Charge Partitioning on IM3 Prediction in SOI-LDMOS Transistors(01-02-2020)
;Gupta, Shubham ;Nikhil, Krishnannadar Savithry; ; In this article, the effect of charge partitioning in a silicon-on-insulator lateral double-diffused metal-oxide-semiconductor (LDMOS) transistor on its nonlinearity model is investigated. It is found that the prediction of the third-order intermodulation distortion (IM3) depends on the model equivalent circuit (EC) and appropriate charge assignments at various nodes therein. The investigation is carried out using a highly accurate static model of LDMOS along with a couple of different charge-partitioning schemes in order to single out their effects on the nonlinearity model behavior. We observe that charge partitioning in a more flexible EC framework yields an improved IM3 prediction when compared with the TCAD simulated results. - PublicationNovel low temperature techniques for growth of ultrathin oxides for Strained Si MOS Devices(01-12-2007)
;Kailath, Binsu J.; ; ;Bhattacharya, S. ;Armstrong, B. M. ;Gamble, H. S.McCarthy, J.MOS capacitors with ultrathin (≅1.2 nm) oxide grown by different techniques have been fabricated on Strained Si/Relaxed SiGe/n-Si substrates with linearly graded SiGe. These techniques involve thermal oxidation, chemical oxidation and both followed by anodic oxidation. Significant improvement in interface states has been obtained when oxidation was followed by anodic oxidation. The leakage currents and reliability characteristics have also shown great improvement. Band gap offsets extracted using a simple and novel technique are found to match well with expected values. © 2007 IEEE. - PublicationReduction in gate leakage current of AlGaN/GaN HEMT by rapid thermal oxidation(07-11-2014)
;Sreenidhi, T. ;Rahman, A. Azizur ;Bhattacharya, Arnab; Rapid Thermal Oxidation (RTO) of AlGaN barrier has been employed to reduce the gate leakage current in AlGaN/GaN High Electron Mobility Transistors. Current Voltage (I-V) and Capacitance Voltage (C-V) characteristics of Schottky Barrier diodes and Metal Oxide Semiconductor diodes are compared. At room temperature, reduction in gate leakage current over an order of magnitude in reverse bias and four orders of magnitude in forward bias is achieved upon oxidation. While the gate current reduces upon RTO, gate capacitance does not change indicating gate control over the channel is not compromised. I-V and C-V characterization have been carried out at different temperatures to get more insight into the device operation. - PublicationUnified analytical threshold voltage model for non-uniformly doped dual metal gate fully depleted silicon-on-insulator MOSFETs(01-03-2009)
;Rao, Rathnamala ;Katti, Guruprasad ;Havaldar, Dnyanesh S.; The paper describes the unified analytical threshold voltage model for non-uniformly doped, dual metal gate (DMG) fully depleted silicon-on-insulator (FDSOI) MOSFETs based on the solution of 2D Poisson's equation. 2D Poisson's equation is solved analytically for appropriate boundary conditions using separation of variables technique. The solution is then extended to obtain the threshold voltage of the FDSOI MOSFET. The model is able to handle any kind of non-uniform doping, viz. vertical, lateral as well as laterally asymetric channel (LAC) profile in the SOI film in addition to the DMG structure. The analytical results are validated with the numerical simulations using the device simulator MEDICI. © 2009 Elsevier Ltd. All rights reserved. - PublicationEffect of nitridation on Al/HfO2/Ge MIS capacitors(01-12-2007)
;Kailath, Binsu J. ;Bhattacharya, Sekhar; ; ;McNeill, D. W.Gamble, H.MIS capacitors on nitrided and non-nitrided Ge substrates with HfO 2 as the dielectric have been studied. Effective oxide thickness is found to be reduced after nitridation. Significant improvements in the electrical characteristics are observed for the devices fabricated on nitrided substrates. The value of density of interface states is found to be lower for nitrided device when compared to non-nitrided device. Leakage current is drastically reduced for the nitrided device. The Breakdown field strength is improved from 11.3 MV/cm for the non-nitrided device to 15.89 MV/cm for the nitrided device. © 2007 IEEE. - PublicationAn improved quasi-saturation and charge model for SOI-LDMOS transistors(01-01-2015)
;Prasad, Nitin ;Sarangapani, Prasad ;Nikhil, Krishnan Nadar Savithry; ; In this paper, we report an accurate quasi-saturation model and a nodal charge model for silicon-on-insulator lateral double-diffused metal-oxide-semiconductor (SOI-LDMOS) transistors. First, a model of a 2-D SOI resistor under velocity saturation is developed, which is subsequently incorporated into the drift region of an LDMOS transistor to predict the quasi-saturation effect. The gate-voltage dependence of the quasi-saturation current is also modeled. Second, we propose a new nodal charge model to describe the dynamic behavior of the device. Comparisons of modeling results with device simulation data show that the proposed model is accurate over a wide range of bias. Scalability of the model with respect to the length of the drift region under the field oxide is also demonstrated. Finally, the model is validated under device self-heating conditions and by comparing it with the experimental data. - PublicationReactive ion etching of GaN in SF6 + Ar and SF6 + N2 plasma(01-12-2008)
;Sreenidhi, T. ;Baskar, K.; Reactive ion etching (RIE) of GaN using SF6 + Ar and SF 6 + N2 plasma has been carried out. An improvement in etch rate is observed with SF6 + Ar over SF6 + N2 plasma. Schottky diodes fabricated on the etched surface show the evidence of damage. However, damage is less for the samples etched with SF6 + Ar plasma. The reverse leakage current density and the ideality factor are found to depend on the perimeter to area ratio of the device. This suggests that the damage caused by etching is surface damage and the leakage might be because of the formation of a surface channel. Thermal annealing and surface passivation using ammonium sulfide help in recovering the damage. Optimization of annealing as well as passivation schedule is essential, since increased annealing or passivation time degrades the device characteristics. © 2008 IOP Publishing Ltd. - PublicationA micro-convection model for thermal conductivity of nanofluids(01-11-2005)
;Patel, Hrishikesh E. ;Sundararajan, T.; ; ; Increase in the specific surface area as well as Brownian motion are supposed to be the most significant reasons for the anomalous enhancement in thermal conductivity of nanofluids. This work presents a semi-empirical approach for the same by emphasizing the above two effects through micro-convection. A new way of modeling thermal conductivity of nanofluids has been explored which is found to agree excellently with a wide range of experimental data obtained by the present authors as well as the data published in literature. © Indian Academy of Sciences.