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Surface Chemistry Weekly Review September 19, 2016

Posted by stuffilikenet in Awesome, Science, Star Trek Technology, Toys.
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Things are happening in the thrilling world of surface chemistry (which I know you all care about deeply), so I will attempt to translate from Science to Normal and explain the usefulness of each advance (as I see it. I am never wrong).

First, and array of carbon nanotubes was created by drawing up a substrate from a solution of high-purity nanotubes, causing them to string out nicely.

Abstract Image

The resulting array of CNTs were etched with electrons scoring a resist coating, the remainder of which was washed off with acetone.  Not sure how they got the palladium contacts attached, but that may be just standard solution chemistry.  I can think of two ways to do it, if the CNTs can take it.

The upshot of all this is an array of CNT FETs (50 per micrometer!) with “quasi-ballistic conduction” (meaning really fast, almost effortless electron flow). As reported in Science “The saturated on-state current density is as high as 900 μA μm−1 and is similar to or exceeds that of Si FETs when compared at and equivalent gate oxide thickness and at the same off-state current density. The on-state current density exceeds that of GaAs FETs as well. This breakthrough in CNT array performance is a critical advance toward the exploitation of CNTs in logic, high-speed communications, and other semiconductor electronics technologies“, that last bit being a trifle understated.  This is equivalent to Silicon-based FETs, and more advances are coming.  This technology will most likely supplant silicon-base transistors in the not-too-distant future, giving you and me the ever-increasing computation speed and lower power demands that we associate with The Future of Computing.

Homework: Quasi-ballistic carbon nanotube array transistors with current density exceeding Si and GaAs, Science Advances  02 Sep 2016:Vol. 2, no. 9, Gerald J. Brady1, Austin J. Way, Nathaniel S. Safron1, Harold T. Evensen, Padma Gopalan and Michael S. Arnold

 

Next, Kiel University (Germany; it’s OK, I had to look it up, too) materials scientists found a way to microscopically etch metals so that they could be strongly joined by glue.  Their etching process results in a water- and grease-repellent metal surface which takes glue beautifully: “…the here described novel nanoscale-surface sculpturing based on semiconductor etching knowledge turns surfaces of everyday metals into their most stable configuration, but leaves the bulk properties unaffected.” Possible improvements to everyday life include surface prep for painting, aluminum removal from titanium implants and of course, using glue for metal parts assembly, which will save buckets of time and money, as welding is expensive and often impractical.

Not exactly surface chemistry, but I include it because I feel it’s a fundamental advance in materials science techniques.

Homework:  Making metal surfaces strong, resistant, and multifunctional by nanoscale-sculpturing, M. Baytekin-Gerngross et al, Nanoscale Horiz. (2016)

 

Materials researchers at North Carolina State University have developed a technique that allows them to integrate graphene, graphene oxide (GO) and reduced graphene oxide (rGO) on silicon at room temperature by using a nanosecond-pulsed laser.  They have foolishly tried to insist that this is to be used for medical sensors (and it may well be), but the reduced form of graphene oxide is a semiconducting material.  This could be an alternate route to large-scale manufacturing of graphene-based semiconductors, which means (once again) low-power, small devices for The Future of Computing.

Homework: Wafer scale integration of reduced graphene oxide by novel laser processing at room temperature in air, Anagh Bhaumik1 and Jagdish Narayan, J. Appl. Phys. 120, 105304 (2016)

That’s all for now.  Thanks for reading this far; you are very brave.

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