Browsing by Author "Bhat, K.N."

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    Design of Dual-Material Gate Junctionless FinFET based on the Properties of Materials Forming Gate Electrode
    (Taylor and Francis Ltd., 2024) Mathew, S.; Bhat, K.N.; Nithin; Rao, R.
    This work elaborately investigates the electrical behaviour and short channel performance of Dual-Material Gate Junctionless Fin Field Effect Transistors (DMG-JLFinFETs) with multiple-gate metal pairs and varying gate metal length ratios. Rigorous analysis on the nature of DMG-JLFinFET with gate length as low as 10 nm is done using a device simulator by Silvaco, Inc. The gate material closer to the source, namely M1, has a dominating influence on the threshold voltage (Vth) and tunnelling current (Itunn) than the gate material closer to the drain (named M2) in a DMG-JLFinFET. Itunn is lower when the work function of M1 (ΦM1) is greater than the work function of M2 (ΦM2). The relative change in threshold voltage is minimum for Platinum–Gold (PtAu)-DMG-JLFinFET (0.68%). Titanium–Aluminium (TiAl) and Nickel–Titanium (NiTi) gate material pairs, having the same work function difference of 0.38 eV, have the least Drain-Induced Barrier Lowering (DIBL) of 12.88 mV/V. A better Sub-threshold Swing (SS) is observed for DMG-JLFinFET having ΦM1 < ΦM2. For devices with ΦM1 > ΦM2, SS can be improved by making a length of M1 (LM1) greater than 70% of the total gate length (Lg). © 2024 IETE.
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    Effect of reflow temperature and substrate roughness on wettability, IMC growth and shear strength of SAC387/Cu bonds
    (2014) Bhat, K.N.; Prabhu, K.N.; Satyanarayan
    The effect of reflow temperature and substrate surface roughness on wettability, intermetallics and shear strength of Sn-3.8Ag-0.7Cu solder alloy on copper (Cu) substrate was studied. It was found that increase in reflow temperature and substrate surface roughness improved the wettability of solder alloy. The size of needle shaped Cu6Sn5 IMCs (intermetallic compounds) increased with increase in temperature. The morphology of IMCs transformed from long to short needles with increase in substrate roughness. Shear strength and shear energy of the solder bond on rough Cu surfaces were found to be higher than that on smooth Cu surfaces. However, the sheared surfaces of the solder bond on rough Cu surface exhibited a transition ridge characterised by sheared IMCs whereas solder bond on smooth Cu surfaces exhibited completely ductile failure. Although, rough surface exhibited higher shear strength and shear energy, smoother surface is preferable due to its predominant bond failure in the solder matrix. 2013 Springer Science+Business Media New York.
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    Effect of reflow temperature and substrate roughness on wettability, IMC growth and shear strength of SAC387/Cu bonds
    (2014) Bhat, K.N.; Prabhu, K.; Satyanarayan, S.
    The effect of reflow temperature and substrate surface roughness on wettability, intermetallics and shear strength of Sn-3.8Ag-0.7Cu solder alloy on copper (Cu) substrate was studied. It was found that increase in reflow temperature and substrate surface roughness improved the wettability of solder alloy. The size of needle shaped Cu6Sn5 IMCs (intermetallic compounds) increased with increase in temperature. The morphology of IMCs transformed from long to short needles with increase in substrate roughness. Shear strength and shear energy of the solder bond on rough Cu surfaces were found to be higher than that on smooth Cu surfaces. However, the sheared surfaces of the solder bond on rough Cu surface exhibited a transition ridge characterised by sheared IMCs whereas solder bond on smooth Cu surfaces exhibited completely ductile failure. Although, rough surface exhibited higher shear strength and shear energy, smoother surface is preferable due to its predominant bond failure in the solder matrix. © 2013 Springer Science+Business Media New York.
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    Impact of the diaphragm structure on the linearity and temperature sensitivity of low-pressure piezo-resistive MEMS pressure sensors
    (Institute of Physics Publishing helen.craven@iop.org, 2020) Nithin, N.; Rao, R.; Bhat, K.N.
    This paper presents result of a detailed simulation study aimed at optimizing the different diaphragm structures of silicon micro machined MEMS pressure sensor for operation and measurement of the low-pressure ranges(600mbar). We first show that the conventional arrangement of the Wheatstone bridge resistors realized using the "Flat diaphragms" give rise to large temperature dependence of the offset voltage which affects the sensitivity and linearity of the pressure sensors during operation in the temperatures ranging from-40Cto+80C, thus making the temperature compensation of the sensor output voltage rather tedious and impossible in certain instances. We further demonstrate that, this issue can be circumvented and excellent linearity with minimum dependence of the offset-voltage, sensitivity and linearity can be achieved by using "sculptured diaphragms" with optimized diaphragm dimensions. Towards this goal, in this paper, we present a set of simulation studies involving optimization of the pressure sensor diaphragm dimensions and structures with single and multiple boss structures to achieve better sensitivity, linearity, and at the same time minimize temperature drift, and to achieve better repeatability. © Published under licence by IOP Publishing Ltd.
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    Investigations on the effect of Dual Material Gate work function on DIBL and Subthreshold Swing in Junctionless FinFETs
    (Institute of Electrical and Electronics Engineers Inc., 2020) Mathew, S.; Nithin; Bhat, K.N.; Rao, R.
    This paper investigates the influence of gate material work function on the electrical characteristics as well as short channel effects exhibited by Dual Material Gate-Junctionless FinFETs (DMG-JLFinFETs) with channel length as low as 10 nm. 3D TCAD simulations performed on these devices show that various device parameters like threshold voltage, ON-current, etc, are influenced by the work function difference between the control gate and screen gate material of DMG-JLFinFET. DMG-JLFinFETs exhibit very low Drain Induced Barrier Lowering (DIBL), far lesser than its Single Material Gate (SMG) counterpart. Subthreshold Swing (SS) of DMG devices is higher than SMG devices. The optimal ratio of control gate length to total gate length in DMG-JLFinFET is found to be between 0.5 and 1 for better suppression of short channel effects. © 2020 IEEE.
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    Performance Enhancement of Dual Material Gate Junctionless FinFETs using Dielectric Spacer
    (Taylor and Francis Ltd., 2024) Mathew, S.; Bhat, K.N.; Nithin; Rao, R.
    In this work, a detailed investigation is done on the effectiveness of various spacer materials having different spacer lengths (LSP), in improving the performance of Dual-Material Gate-Junctionless FinFET (DMG-JLFinFET). Various performance metrics, such as Drain Induced Barrier Lowering (DIBL), Sub-threshold Swing (SS), ON current (ION), OFF current (IOFF), ratio of ION to IOFF (ION/IOFF), and tunneling current (Itunn), are closely monitored at gate lengths (Lg) down to 10 nm. DIBL degradation of 3.46 mV/V and SS degradation of 4.97 mV/dec are observed when Lg scales down from 30 nm to 10 nm. Except for the case of Itunn, other performance metrics improve with an increase in dielectric constant and length of spacer materials. The optimum performance of DMG-JLFinFET with a channel length of 10 nm is obtained when LSP is 5 nm. Enhancement in analog performance metrics is observed when high κ materials are used as spacers. Transconductance Generation Factor (TGF) improves from 35.86 V−1 to 47.4 V−1 and intrinsic gain increases from 6.93 dB to 11.98 dB when high κ dielectric materials like TiO2 are incorporated as spacers in a DMG-JLFinFET. © 2024 IETE.