Century-old problem: ... professor finds out what causes low-frequency electronic 1/f noise

Phys.Org ^ | 03-07-2013 | Provided by University of California - Riverside

[Red Badger]

FULL TITLE:

Solving nearly century-old problem: Using graphene, professor finds out what causes low-frequency electronic 1/f noise

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A University of California, Riverside Bourns College of Engineering professor and a team of researchers published a paper today that show how they solved an almost century-old problem that could further help downscale the size of electronic devices.

The work, led by Alexander A. Balandin, a professor of electrical engineering at UC Riverside, focused on the low-frequency electronic 1/f noise, also known as pink noise and flicker noise. It is a signal or process with a power spectral density inversely proportional to the frequency. It was first discovered in vacuum tubes in 1925 and since then it has been found everywhere from fluctuations of the intensity in music recordings to human heart rates and electrical currents in materials and devices. The importance of this noise for electronics motivated numerous studies of its physical origin and methods for its control. For example, the signal's phase noise in a radar or communication gadget such as smart phone is determined, to a large degree, by the 1/f noise level in the transistors used inside the radar or smart phone. However, after almost a century of investigations, the origin of 1/f noise in most of material systems remained a mystery. A question of particular importance for electronics was whether 1/f noise was generated on the surface of electrical conductors or inside their volumes. A team of researchers from the UC Riverside, Rensselaer Polytechnic Institute (RPI) and Ioffe Physical-Technical Institute of The Russian Academy of Sciences were able to shed light on 1/f noise origin using a set of multi-layered graphene samples with the thickness continuously varied from around 15 atomic planes to a single layer of graphene. Graphene is a single-atom thick carbon crystal with unique properties, including superior electrical and heat conductivity, mechanical strength and unique optical absorption. In addition to Balandin, who is also the founding chair of the materials science and engineering program at UC Riverside, the team of researchers included: The team included: Guanxiong Liu, a research associate in Balandin's Nano-Device Laboratory (NDL); Michael S. Shur, Patricia W. and C. Sheldon Roberts Professor of Solid State Electronics at RPI; and Sergey Rumyantsev, research professor at RPI and Ioffe Institute.

"The key to this interesting result was that unlike in metal or semiconductor films, the thickness of graphene multilayers can be continuously and uniformly varied all the way down to a single atomic layer of graphene – the ultimate "surface" of the film," Balandin said. "Thus, we were able to accomplish with multilayer graphene films something that researchers could not do with metal films in the last century. We probed the origin of 1/f noise directly." He added that previous studies could not test metal films to the thicknesses below about eight nanometers. The thickness of graphene is 0.35 nanometers and can be increased gradually, one atomic plane at a time. "Apart from the fundamental science, the reported results are important for continuing the downscaling of conventional electronic devices," Balandin said. "Current technology is already at the level when many devices become essentially the surfaces. In this sense, the finding goes beyond graphene field." He also noted that the study was essential for the proposed applications of graphene in analog circuits, communications and sensors. This is because all these applications require acceptably low levels of 1/f noise, which contributes to the phase noise of communication systems and limits sensor sensitivity and selectivity. The results of the research have been published in the journal Applied Physics Letters.

[razorback-bert]

I bought stock in a graphene manufacting company a couple of weeks ago. It has lost half it value since I bought it.

[zeugma]

Uh, I’m thinking that if you’re talking about noise, you’d be better off with Ummagumma (sp?) than DSOTM. “Several species of small furry animals gathered together in a cave and gorrving with a pict” is the only song I’ve ever heard that I simply cannot read to. The noise disrupts my brain to the point that I either have to just skip it, or wait until it’s over.

[Bloody Sam Roberts]

...an age of microelectronics to make our current iPhones and Droid devices look like the bag phones of the 80s.

Why? I find the current crop of smartphone touch screens barely navigable as is. Plus, why would someone want a smartphone display that requires a magnifying glass to see?

[rarestia]

You’re thinking from a size perspective. I’m thinking from a capabilities standpoint. Today’s smartphones require very small electronics to pump out some impressive hardware capabilities for something so tiny. By comparison, we could get horsepower comparable to an enterprise server in a tablet. This would have immense implications for the current datacenter and consumer-level electronics.

Imagine 60”+ televisions that weight less than a pound, ultra-dense memory and solid state disk drives allowing for hundreds of gigabytes or even terabytes of RAM and possibly petabytes of disk in a solid state form, all in the same packaging of today or even smaller, entire rooms full of electronics compacted down to something the size of a phone or a tablet. The applications are almost unimaginable.

[Bloody Sam Roberts]

Ahh...good point.

[Ernest_at_the_Beach]

Yes,...And still I need a BIGGER MAGNIFIER...

[B4Ranch]

Now if they find a cure for tinnitus we might just be able to hear the true sounds.

[Marine_Uncle]

RE: "Yes,...And still I need a BIGGER MAGNIFIER..."
I can sympathize with that dilemma. :)
Interesting article by the way.

[SunkenCiv]

Thanks Red Badger and Ernest.

were able to shed light on 1/f noise origin using a set of multi-layered graphene samples with the thickness continuously varied from around 15 atomic planes to a single layer of graphene.

FR's graphene keyword is pretty impressive, btw. A ping to an old lurker along with some old engineers as well as the String Theory members.

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[2 Kool 2 Be 4-Gotten]

Things that make you go hummmmmmmm.

[NoCmpromiz]

So where does it come from?

All visual indications point to The Dark Side of the Moon..

[GOPJ]

Imagine 60”+ televisions that weight less than a pound, ultra-dense memory and solid state disk drives allowing for hundreds of gigabytes or even terabytes of RAM and possibly petabytes of disk in a solid state form, all in the same packaging of today or even smaller, entire rooms full of electronics compacted down to something the size of a phone or a tablet. The applications are almost unimaginable.

Wallpaper. Floor to ceiling wallpaper: click your cell phone and it goes from beige 'paint' to printed wallpaper. Click again and it's grandma's kitchen - with Gram having morning coffee with you - click again - - Niagara Falls in real time...

[GOPJ]

...1/f noise becomes dominated by the volume noise when the thickness exceeds ∼7 atomic layers (∼2.5 nm). The 1/f noise is the surface phenomenon below this thickness.

Interesting - thanks for sharing.

[neverdem]

anybody have a Ham Radio ping list?

cgk had a list of lists linked at cgk's homepage:

http://www.freerepublic.com/~cgk/

It's old. Denver Ditdat might not have it now.

[neverdem]

Thanks for the abstract.

[rarestia]

They’ve already embedded ferrous materials in paints to make “chalkboard” walls. They’re magnetically attractant and actually a pretty neat idea for kids.

If they can embed organized strains of graphene in a wall covering, like wallpaper, then I don’t see why this scenario isn’t plausible. It would be a giant monitor on which you could display anything. They would, however, have to be static pictures, I’d imagine. Refresh rates, like with televisions and TFTs, are required to present a moving picture. Unless they can embed microprocessors in the walls or in the material itself, it wouldn’t have sufficient power to display a moving picture.

They might, however, have a way to make a slow-moving presentation look good. Something like slow-moving clouds or tides.

Again, the applications are almost limitless.

[usconservative]

That’s how I interpreted it .......

[Red Badger]

Sounds Of Silence
Artist: Simon & Garfunkel
Album: Sounds Of Silence

Hello darkness, my old friend
I’ve come to talk with you again
Because a vision softly creeping
Left its seeds while I was sleeping
And the vision that was planted in my brain
Still remains
Within the sound of silence

In restless dreams I walked alone
Narrow streets of cobblestone
‘Neath the halo of a street lamp
I turned my collar to the cold and damp
When my eyes were stabbed by the flash of a neon light
That split the night
And touched the sound of silence

And in the naked light I saw
Ten thousand people, maybe more
People talking without speaking
People hearing without listening
People writing songs that voices never share
And no one dared
Disturb the sound of silence

“Fools”, said I, “You do not know
Silence like a cancer grows
Hear my words that I might teach you
Take my arms that I might reach you”
But my words, like silent raindrops fell
And echoed
In the wells of silence

And the people bowed and prayed
To the neon god they made
And the sign flashed out its warning
In the words that it was forming
And the sign said, “The words of the prophets are written on the subway walls
And tenement halls”
And whispered in the sounds of silence