Physicists Create a Working Transistor From a Single Atom

stupendou writes "Australian and American physicists have built a working transistor from a single phosphorus atom embedded in a silicon crystal. The group of physicists, based at the University of New South Wales and Purdue University, said they had laid the groundwork for a futuristic quantum computer that might one day function in a nanoscale world and would be orders of magnitude smaller and quicker than today's silicon-based machines."

Comments

But...

[Anonymous Coward]

Can we really call it a transistor? Sure it can change states, but a real transistor does a whole lot besides.

Radiation hardening

[DigiShaman]

With transistors that small, how would you harden a microchip against radiation? Would the extra redundancy not make it worthwhile. That is to say, is there an optimal compromise between transistor size and resources consumed through redundancy allocation?

Re:Radiation hardening

[Sycraft-fu]

Do you need to? Are normal computers radiation hardened? I realize there are situations that do use that, like satellites, but they are always behind the curve technology wise due to the extra requirements for a harsh environment, so no problem with this, they could use more classic lithography.

Also you could just encase the chip/board/unit/whatever in something to resist radiation. I'm not saying that is a workable solution in all cases, but in many it would be just fine. Just shield the chip and call it good.

Re:Radiation hardening

[RKBA]

A transistor one atom in size would be much less likely to be hit by an ionizing particle because of its tiny cross-sectional area (ie; only one angstrom in diameter).

Re:Radiation hardening

[__aaltlg1547]

Normal computers aren't radiation hardened, but the point is that they store and process information based on more than just the quantum state of a single particle. It takes a great deal more unwanted energy to cause them to flip to the undesired state. This kind of thing would many times more vulnerable to stray radiation, heat or stray electromagnetic fields than the smallest conventional transistor.

But any practical computer is going to have to contain millions of these things. If you want to carry out a computation with such a machine, either you have to protect it with conditions that have a minimal chance of causing a computational error or you will have to engineer it with redundancy and error correction mechanisms that may in the end be bigger and less reliable than a classical solution.

Re:A transistor made of a single atom?

[artor3]

We were making single atom transistors ten years ago, but it was hit or miss whether the atom would end up in the right place.

Today, we can place the atom with high precision, in silicon, so that the devices can be made reliably.

Ten years from now, who's to say we won't be able to mass produce them?

Not to nay-say, but...

[koolguy442]

I hate being a nay-sayer, but the NYT article is making quite a spectacle about this whole thing. What the group has truly done is demonstrate a novel method for placing a single phosphorus atom within silicon and proceeded to measure the semiconducting properties of the resultant device with quite good precision. Because the doping is the result of a single atom, they can resolve more than just "on" and "off", and in fact can read three states from it, so it gets its quantum computing title.

As a materials scientist, I'm worried that they don't show any long-term data and all their results appear (from my not-so-thorough reading of the originating Nature Nanotechnology report) to be based on a single device. How repeatable is this result and how consistent are the signals across multiple devices? How far will the phosphorus atom diffuse over the lifetime of the device? Or even over the first few hours of its operation at room temperature? How closely can these devices be placed to each other on the silicon chip without getting cross-interference or depriving the dopant of its discrete quantum states? The dopants in a normal device aren't too terribly close to each other. And finally, how big must the surrounding structure be?

Don't get me wrong, this is excellent science and well deserving of its publication in such a prestigious journal, but the spectacle that the NYT is creating around this and the dreams of such a tiny device is a bit premature.

Re:A transistor made of a single atom?

[viperidaenz]

That would have been well over 30 years ago, since 1500nm was reached in 1982 and 800nm in 1989.
The process size is virtually a straight line on a log10 scale. Going on the last 40 years we'll be at 1nm by 2030. Its an order of magnitude every 10 - 15 years

Heisenberg says "NO"

[stochasticevent]

First, some background: Most agree that Moore’s law, which has held firm, will meet its demise in a matter of decades. This will likely signal the end of the silicon era. The basic problem is the limitation of the ultraviolet process by which a hundred million or more transistors are etched onto increasingly smaller silicon wafers. But another problem is perhaps more daunting: When computing is reduced to smaller and smaller quantum scales (currently, the chip inside your computer can be 5 or so atoms across), one runs into the Heisenberg Uncertainly Principle; it simply becomes impossible to tell exactly where an electron is, so there is leakage. In other words, using quantum computers, given contemporary materials and knowledge, 2+2 might eventually end up being 4, but there might need to be built in recursion and tautological algorithms. Computation using atoms has already been done, as pointed out by another poster. Think it will be a while before we see them at Best Buy. Also, it still seems like silicon based technology

Re:A transistor made of a single atom?

[joocemann]

You aren't into nanotech, are you?

Massive nano-scale manufacturing is much closer to reality than you seem to assume. Look into it. No spoon on hand for me to spoonfeed right now, sorry.

Re:A transistor made of a single atom?

[cold fjord]

You aren't into nanotech, are you?

Massive nano-scale manufacturing is much closer to reality than you seem to assume. Look into it. No spoon on hand for me to spoonfeed right now, sorry.

Did you read how they did it?

The scientists placed the single phosphorus atom using a device known as a scanning tunneling microscope. They used it to essentially scrape trenches and a small cavity on a surface of silicon covered with a layer of hydrogen atoms. Phosphine gas was then used to deposit a phosphorus atom at a precise location, which was then encased in further layers of silicon atoms.

Does that seem like a scalable process to you? Here is what the article says:

While offering astounding precision for research, these microscopes are not currently applicable as manufacturing tools to make chips that contain billions or even trillions of transistors. Moreover, the devices now operate at very low temperatures.

They made them with a method not applicable for manufacturing, and, as a bonus, they are cryo-cooled. They are still at the level of demonstrating / playing / investigating.

I think your spoon would prove pretty empty..... or maybe there is no spoon.