CNT Interconnects Research Articles

Accurate Voltage-Dependent Transmission Line Model for Carbon Nanotube Interconnects and the Delay Calculation

In this work, a distributed carbon nanotube interconnect model employing voltage-dependent resistance and voltage-dependent capacitance is presented. In order to calculate the delay of the carbon nanotube interconnects, the developed model is imported into HSPICE using Verilog-A language. Delays of (9, 0), (12, 0) and (8, 8) metallic CNT interconnect sections are obtained using the proposed model and compared to the delay calculation of previous models. The comparison shows considerable difference hence importance of the voltage-dependent model.

Carbon nanotubes for next generation very large scale integration interconnects

We investigated the application of one-dimensional fluid model in modeling of electron transport in carbon nanotubes and equivalent circuits for interconnections and compared the performances with the currently used copper interconnects in very-large-scale integration (VLSI) circuits. In this model, electron transport in carbon nanotubes is regarded as quasi one-dimensional fluid with strong electron-electron interaction. Verilog-AMS in Cadence/Spectre was used in simulation studies. Carbon nanotubes of the types single-walled, multiwalled and bundles were considered for ballistic transport region, local and global interconnections. Study of the S-parameters showed higher transmission efficiency and lower reflection losses. Theoretical modeling and computer-aided simulation studies through a complimentary CNT-FET inverter pair, interconnected through a wire, exhibited reduced delays and power dissipations for carbon nanotube interconnects in comparison to copper interconnects in 22 nm and lower technology nodes. The performance of CNT interconnects was shown to be further improved with increase in number of metallic carbon nanotubes. Our study suggests the replacement of copper interconnect with the multiwalled and bundles of single-walled carbon nanotubes for the sub-nanometer CMOS technologies.

Versatile transfer of aligned carbon nanotubes with polydimethylsiloxane as theintermediate

A simple technique to transfer aligned multi-walled carbon nanotubes (MWCNTs) isdemonstrated in this work. With polydimethylsiloxane (PDMS) as the transfer medium,as-grown or patterned MWCNT arrays are directly transferred onto a wide variety ofPt-coated substrates such as glossy paper, cloth, polymers, glass slides, and metal foils atlow temperatures. The surface of the transferred CNTs is cleaner with better alignment,compared with the as-grown one. Furthermore, the transferred CNTs show strong adhesionand good electric contact with the target substrates. A maximal current density of∼104 A cm−2 has been achieved from the CNT interconnects prepared with this technique.Because of the lower density and open-ended structures, improved field emissionperformance has been obtained from CNTs transferred on polymers, based onwhich flexible emitter devices can be fabricated. In addition, the surface oftransferred CNTs becomes more hydrophilic, with an averaged contact angle of93.4 ± 5.8°, in contrast to the super-hydrophobic as-grown CNT surface (contact angle151.6 ± 5.5°). With versatile properties and flexible applications, the technique provides a simple andcost-effective way towards future nanodevices based on CNTs.

Modeling Electronic Properties of Multiwall Carbon Nanotubes

Reviewing experimental results and based on the physical reasoning, we present a basic circuit model for Multiwall carbon nanotubes (MWCNTs), which can simulate different experimental results. Investigation of different results confirms the severe effects of fabrication process (nanotube and contacts) on electronic properties of the MWCNTs. The circuit model has been developed to show the performance improvements of a CNT interconnect when the single‐wall carbon nanotube (SWCNT) is replaced by an MWCNT. To calculate the current‐voltage characteristic and the switching delay of MWCNTs, we have simulated their DC and AC properties, respectively, using the developed transmission line models. Based on the physical models, the elements of the circuit model can be changed so that the simulation and the practical measurements for an MWCNT can correspond. Switching Delays of the MWCNTs and SWCNTs are calculated and compared for different cases.