Papers by Keyword: Interconnect

Abstract: In the present nanoscale regime, mixed carbon nanotube bundles (MCBs) are considered to be highly promising interconnect options. This research paper introduces a spatially arranged mixed carbon nanotubes (CNTs) bundle (MCB), wherein single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) occupy equal halves in the MCB. An equivalent single conductor (ESC) model for MCB is employed to analyze the interconnect performances in terms of signal transmission delay and dynamic crosstalk delay at different technology nodes (i.e., 32nm, 22nm, and 16 nm). Encouragingly, a significant reduction in signal transmission delay and dynamic crosstalk induced delay are observed at 32 nm technology node. It is observed that at 32 nm technology node, the propagation delay and crosstalk induced delay significantly improves by 29.40% and 55.53%, respectively, compared to 22 nm technology node and 187.88% and 185.94%, respectively, compared to 16 nm technology node. The improvement in interconnect performances can primarily be attributed to the improvement in the number of conducting channels inside the MCB at 32 nm, which greatly impacted the interconnect parasitics such as quantum resistance, quantum capacitance, kinetic inductance etc.

Abstract: Solid oxide fuel cell has become one of the interest in the sustainable energy field. In order to improve the efficiency of a solid oxide fuel cell (SOFC), the interconnect must be coated with a protective coating of (MnCO)₃O₄ spinel coated stainless steel. Commercial manganese cobalt (MnCO)₃O₄ was used as a protective coating on ferritic stainless steel in this study using the electrophoretic deposition (EPD) coating technique. This article examines the impact of voltage deposition towards morphological characteristics. The goals of these studies are to find the best interconnect coating parameter while experimenting with voltage deposition. The spinel coated interconnect (MnCO)₃O₄ was studied using Elemental Energy Dispersive X-ray Spectroscopy (EDS). The surface morphology and coating thickness are examined using a Scanning Electron Microscope (SEM). X-ray diffraction (XRD) is used to determine the phase of the spinel coated interconnect. The EPD coating technique for (MnCO)₃O₄ spinel coated interconnect is carried out in an aqueous suspension with 30V and 40V with coating durations of 20s, 30s, 40s, 50s, and 60s. By observing the deposition morphology and thickness coating at 30V and 40V, the best covering parameter for interconnect is 30V, 40s which fulfil the interconnect requirement.

Abstract: The evaporation of volatile chromium species from ferritic stainless steels (FSSs) used as interconnect is well-known as degradation source for planar solid oxide fuel cell (SOFC) stacks. This work presents a feasibility study to quantify chromium evaporation from FSSs. It is based on measuring carbon dioxide produced by an intermediate reaction. Cr evaporated is collected by sodium carbonate forming sodium chromate and carbon dioxide. Measuring the resulting carbon dioxide allowed to quantify online the amount of reacted chromium with the carbonates. The post-experiment quantification of sodium chromate confirmed the applicability of the proposed method.

Abstract: The chapter introduces components and working principle of solid oxide fuel cells (SOFCs). It is followed by the explanation on the choices of materials focussing on ferritic stainless steels. The review is further made on the required properties of these steels, i.e. low oxidation rate, low chromium species volatilisation rate, high electrical conductivity and good scale adhesion. For the oxidation aspect, the behaviour of stainless steel interconnect in cathode, anode (hydrogen and biogas), and dual atmospheres are described. Surface modification by pre-oxidation and coatings to improve the oxide electrical conductivity and to reduce chromium species volatilisation is finally reviewed.

Abstract: We report the initial results of using co-sputtered Pt:Ti 80:20 at. % composition ratio metallization as a diffusion barrier against gold (Au) and oxygen (O), as an interconnect layer, as well as forming simultaneous ohmic contacts to n-and p-type 4H-SiC. Having a single conductor with such combined multi-functional attributes would appreciably reduce the fabrication costs, processing time and complexity that are inherent in the production of SiC based devices. Auger Electron Spectroscopy, Focused Ion Beam-assisted Field Emission Scanning Electron Microscopy and Energy Dispersive Spectroscopy analyses revealed no Au and O migration to the SiC contact surface and minimal diffusion through the Pt:Ti barrier layer after 15 minutes of exposure at 800 oC in atmosphere, thus offering potential long term stability of the ohmic contacts. Specific contact resistance values of 7 x 10^-5 and 7.4 x 10^-4 Ω-cm² were obtained on the n (N_d=7 x 10¹⁸ cm^-3) and p (N_a=2 x 10²⁰ cm^-3) -type 4H-SiC, respectively. The resistivity of 75 μΩ-cm was obtained for the Pt:Ti layer that was sandwiched between two SiO₂ layers and annealed in pure O ambient up to 900 °C, which offers promise as a high temperature interconnect metallization.

Abstract: A ferritic stainless steel (FSS) AISI 430 coated by (Mn_xCo_1-x)₃O₄ spinel has been intensively studied for its potential in application as an interconnect of a solid oxide fuel cell (SOFC). In this study, in order to develop fabrication of (Mn_xCo_1-x)₃O₄ coatings, Mn-Co coatings on AISI 430 by an electrodeposition technique was adopted. The electric direct current (DC) and alternative current (AC) modulated DC (AC+DC) signals were utilized to drive voltage levels for electrodeposition. By varying the duty of the AC+DC signals from 25 % to 50 %, the ratio of Mn and Co composition in the coating changed, consequently by this technique it is possible to adjust the composition of binary alloy coating. The fabricated coatings also exhibited different morphologies indicating nucleation and grain growth process of various oxide scales of Mn-Co. The oxidation behavior is also investigated to evaluate the quality of the coatings.

Abstract: A ferritic stainless steel has been intensively studied for its potential in application as an interconnect for a solid oxide fuel cell (SOFC). However, at such a high operating temperature chromia in the gaseous phase can contaminate the cathode of the SOFC, and consequently the performance of the device degrades rapidly. To overcome this problem, two kind of ceramics, (La,Sr)CrO₃ perovskite and Mn-Co oxide spinel were prepared as coatings on the stainless steel AISI 430 to investigate on chromia evaporation at 800°C. In this present work, the (La,Sr)CrO₃ and Co-Mn layers were formed by a sol-gel dip coating and an electrodeposition technique, respectively. The coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), rates of oxidation and rates of chromia evaporation. The coated specimens exhibited the protective behavior with a lower rate of oxidation, as well as a lower rate of chromium evaporation than the uncoated specimen both in the atmosphere of dry and humidified oxygen. But the reduction of the chromia evaporation rates of (La,Sr)CrO₃ coatings was insignificant due to the presence of Cr₂O₃ phase in the coatings.

Abstract: In an attempt to reduce the oxidation and Cr evaporation rates of solid oxide fuel cells (SOFCs) interconnect, Cu-Fe coating was developed on the AISI 430 ferritic stainless steel substrate by a pulsed current electrodeposition method. Effects of pulse frequency on properties and performance of the fabricated coating were investigated. Results show that Cu-Fe alloy was sucessfully fabricated using pulse deposition methods. The variation of pulsed frequency during pulse current deposition strongly influence the coating morphology and its composition. The increase of pulse frequency tend to increase the Cu-Fe grain size. Moreover, the amount of Cu particles decreases with the increase of pulse frequency.

Abstract: AISI 441 ferritic stainless steel is a good candidate for metallic interconnects in solid oxide fuel cells (SOFCs). The minor elements Ti and Nb are used to stabilize the ferritic matrix and also to reduce creep by a combination of solid solution strengthening and precipitation of intermetallic Laves phase particles along the grain boundaries. However their influence on the oxidation behavior is not well understood. This study focuses on the early stages oxidation (from 4 to 24 h) at 800 °C of AISI 441 under 5% H₂O in O₂. A relatively smooth micro-crystallized oxide scale and Ti, Nb containing nodules are observed. The internal microstructure of these objects is studied by FIB tomography which allows computing cross sectional views in any direction of interest. FIB study reveals a complex microstructure and a development strongly linked to the presence of niobium and/or titanium in the substrate.

Abstract: A novel signaling technique for on-chip carbon nanotube interconnect aiming a higher bitrate in the range of Terahertz (THz) with low power dissipation, employing the current mode signal transportation is proposed in this paper. The technique exploits the combined advantages of current mode signaling and carbon nanotube. Using the equivalent circuit model, the transfer function is derived for the current mode carbon nanotube interconnect. Current mode signaling through carbon nanotube interconnect is simulated in MATLAB and HSPICE to study its efficiency and performance. The results are compared with the existing voltage mode CNT, current mode copper and optical interconnect. The proposed current mode signaling for carbon nanotube interconnect achieves 10² times lesser power delay product and 90% lesser delay than voltage mode. It exhibits lesser delay, 1000 times in local and 1.2 times in global and lesser power delay product by the factor of 1000 as compared with optical interconnect.