Science Special: Computer Memory Device

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ASU electrical engineering Professor Michael Kozicki talks about a new computer memory device being developed at Arizona State University that would greatly increase the capacity of flash drives.

Ted Simons:
Welcome to "Horizon." I'm Ted Simons. This is a special edition of "Horizon." Tonight we're going to show you several science innovations. We start with a look at a new flash memory device being developed at Arizona State University. Richard Ruelas will talk to an ASU professor. But first, Mike Sauceda tells us more about the device.

Mike Sauceda:
Imagine a thumb drive with 1,000 times the memory capacity of a 1 gigabyte thumb drive, the type commonly sold now. A new type of memory device being worked on at Arizona State University holds the promise of that kind of memory power within a few years. The device is a type of flash memory, which has no moving parts. But instead of using electrons to store memory, the new type of memory used charged atoms or ions. At the incredibly small scope of computer memory, electrons can leak from one circuit to another, short circuiting memory. That doesn't happen with this new type of memory, called a programmable metallization cell.

Sarth Puthenthermadan:
Since we are not depending on electrons being trapped inside a layer, we are just depending on a metal link between two metal layers. So once it's formed, we don't have to worry about any electrons leaking. Once it's formed, even if it gets smaller, the metal link is the same. There's no leakage of anything. No resistance loss or anything as we get smaller.

Mike Sauceda:
The new device uses electrical resistance to store memory. In the device, copper can be turned into nano-wires at will. And that process can be reversed. Providing an on and off state needed for memory.

Sarth Puthenthermadan:
Basically we have ions diffusing in the glass, and it forms a link between two metal layers. So once we form a complete link between the two metal layers, we have a conductive bond. So basically it's a low-resistance state because we have a link. So that's one state and once we remove it, we switch between those two states and it works as a memory device.

Mike Sauceda:
The device is still in the experimental stage. It's made by depositing a layer of copper onto a layer of glass. That's ccomplished by heating up the materials until they vaporize. After the device is made, it's taken to another room for testing.

Sarth Puthenthermadan:
This is our electrical testing lab where we test the devices we make in the other lab. So we test whether the devices are working, whether the data is writing, whether the resistance is switching from the off to the on state.

Mike Sauceda:
Tiny probes provide the electrical charge for the test.

Sarth Puthenthermadan:
This testing helps us to understand how the devices work under different current conditions and voltage conditions, and so this is the first starting point of our testing. This is where we test our devices as soon as we make them to know how everything is. We can test the retention and endurance.

Mike Sauceda:
Besides more memory, the new device also holds the promise of running cooler and costing less.

Richard Ruelas:
With me to talk more about his new memory device is Dr. Michael Kozicki an electrical engineering professor at ASU. Thanks for joining us this evening.

Michael Kozicki:
Good to be here, thank you.

Richard Ruelas:
This stuff is very complicated -- I guess let me ask you to explain how the chip we kind of understand now works, versus what you've developed.

Michael Kozicki:
Right now, the way memory works, the memory in your computer, the memory in your cell phone, your digital camera, your mp3 player tends to involve the storage of charge. You can think of electrons as a fluid -- we pour them into little buckets, and that way we store information. The trouble is, as we try to pack more and more information into a smaller and smaller space, the little buckets get smaller and smaller. The trouble then is, the electrons are more difficult to detect because there's fewer of them, and when they leak out, it becomes a more serious problem to detect that charge. So what we've done is replaced electrons with a nano wire that we can grow and retract, just by applying a very, very small voltage.

Richard Ruelas:
In the package, they talked about leaking out. To the consumer, how do you know that your device is leaking out?

Michael Kozicki:
That's a very good question. One way, of course, the -- the status quo, as far as the technology is concerned -- you have to guarantee, for example, flash memory to be able to store data for 10 years, so if you take a digital picture, the flash has to store the information for 10 years, so obviously, you put it aside, forget about it and come back, you can still download the picture of your toddler many years later.

Richard Ruelas:
It's just holding that charge.

Michael Kozicki:
Exactly. The trouble is future generations, they're already beginning to see they come back after a few years, or still, a few months, and that information is gone because the charge has leaked out. It's not happening in your devices now, but obviously, people don't want to sell memory that forgets.
Richard Ruelas:
And over time, yours will stay because, again, you're changing the physical structure --

Michael Kozicki:
That's exactly right. Rather than storing a little drop of charge, what we're doing is actually growing a little wire, in essence. Like any other wire, once you grow it, it hangs around pretty much forever until you tell it to go away.

Richard Ruelas:
How long ago did you start thinking about this idea?

Michael Kozicki:
We started this program about 11 and a half years ago here at ASU.

Richard Ruelas:
And you mentioned before we came on the air, you told me that you had already licensed and sold, like this is a revenue producer already.

Michael Kozicki:
Indeed, we just got our 25th U.S. patent in this technology last week, and we have about 33 international patents. That strength in patents allowed us to license to three different companies to date. Although, there are a lot more companies interested in this technology, again, for obvious reasons. It's a technology that fits future requirements for memory very, very well indeed.

Richard Ruelas:
What is the order of magnitude we're talking about as far as ability to store and then -- well, I guess you mentioned the permanence of it. So far it seems permanent, right? What about the order of magnitude of the size we can fit into a similar device we see now.

Michael Kozicki:
To date, the work within certain key companies is showing that these devices are scalable down to tens of nanometers in size. In addition, we've also been able to show, as have other people working in the field, that we can store more than one bit of information per cell. In addition to that, it turns out that we can store more than one layer of memory on top of one another. So it's quite easy, with a few calculations -- it's quite easy to imagine a single chip that can store a terabit, or a trillion bits of information. Which is obviously hundreds of times denser than available anything to date.

Richard Ruelas:
Well, I guess we can put it in terms of iPod space.

Michael Kozicki:
One of the articles I saw recently said a million songs. Who could possibly listen to a million songs, I don't know. But it guess where it really comes into its own is with the kinds of things that do require a lot of storage, like high definition video. As one person put it, with enough of these high density storage chips you can begin to record every event in your life in one little device.

Dr. Michael Kozicki:Electrical Engineering Professor, ASU

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