[Constraints] in CNT sorting, processing, alignment, and contacts give rise to nonidealities when CNTs are implemented in densely packed parallel arrays such as those needed for technology… In each scenario, the result has been that, whereas CNTs are ultimately expected to yield FETs that are more conductive than conventional semiconductors for logic applications, CNTs, instead, have underperformed channel materials, such as Si, by sixfold or more. Likewise, in RF applications, depressed on-state conductance and imperfect saturation characteristics arising from metallic CNTs and inter-CNT interactions have limited the maximum frequency of oscillation and linearity.
The paper goes ahead to note how even a solitary metallic CNT can hamper FET (Field Effect Transistor) and result in significantly decreased execution. Building varieties of CNTs at astoundingly high virtue isn’t discretionary — it’s been a major hindrance that organizations like IBM have looked to illuminate for quite a long time. Keeping in mind the end goal to achieve this turning point, the Wisconsin group utilizes a strategy it initially examined in 2014 — gliding evaporative self-get together, as demonstrated as follows.
Here’s how the team describes its findings.
CNT array FETs are demonstrated here with an on-state conductance of 1.7 mS μm−1 and a conductance per CNT as high as 0.46 G0, which is seven times higher than previous state-of-the-art CNT array FETs made by other methods. These FETs are nearing the performance of state-of-the-art single CNT FETs but in the format of an array in which quasi-ballistic transport is simultaneously driven through many, tightly packed CNTs in parallel, substantially improving the absolute current drive of the FETs and, therefore, their utility in technologies.
The exceptional performance of the arrays achieved here is attributed to the combined outstanding alignment and spacing of the CNTs, the postdeposition treatment of the arrays to remove solvent residues and the insulating side chains of the polymers that wrap the CNTs, and the exceptional electronic-type purity of the semiconducting CNTs afforded by the use of polyfluorenes as CNT-differentiating agents. The performance of previous CNT array FETs has not been as high, likely because these FETs have not simultaneously met all of these attributes.
On the off chance that carbon nanotubes could be popularized, it could kickstart semiconductor scaling once more, at any rate for specific applications. Be that as it may, the street between even this leap forward and mass commercialization is still a long one — don’t hope to see CNTs shipping in rationale for another 5-10 years, in the event that it ever does. Other specialty applications may discover more quick advantages. Be that as it may, CPUs and SoCs have a tendency to sit at the very bleeding edge of our innovation bend. That makes it similarly troublesome for new innovation to offer sufficiently extensive enhancements to overwhelm the business.