May 16, 2011

MIT Physicists Aim To Kick-Start Computer Chip Technology

Researchers at MIT and the University of Augsburg have found a way to operate a semiconductive material at a lower voltage, which could inevitably help kick-start a race in computing speed that leveled off a few years ago.

Computer chip makers throughout the 1980's and 1990's continued to out-do each other with faster speeds, moving from megahertz to gigahertz.  Eventually computers ran into a wall in that race as the faster processors lead to an increase in heat, which the machines are unable to handle.

Current silicon chips have transistors that include an electrode known as the 'gate'.  Applying a voltage to the gate causes electrons to accumulate underneath it.  The electrons constitute a channel through which an electrical current passes through, which turns the semiconductor into a conductor.

If the voltage at which the gate operates can be lowered, then there would be less heat generated and clock speeds can be ramped up again.

The team of researchers managed to do that by combining lanthanum aluminate and strontium titanate, both of which are usually insulators and are unable to conduct any current.

So far the researchers have been unable to explain that when the alternating layers of lanthanum oxide and aluminum oxide are treated in a specific way, strange properties start to play out.

The team found that as both layers have a tiny electric charge, an electric potential is created between the top and bottom of the material.  They predicted that if the total thickness of the lanthanum aluminate was increased, it would move electrons from the top of the material to the bottom to avoid a "polarization catastrophe."

This means that when lanthanum aluminate is combined with strontium titanate, a bridge is formed between the two materials in the same way that when a transistor is turned to allow electrons to flow through.  This creates a current necessary for a computer chip to function.

The MIT researchers said link between the two materials is small and can cause a large amount of energy to run between the channel created between the two materials.

The team is struggling to understand why this phenomenon works at room temperature, and has admitted that the method still needs some tweaking. However, they are confident that obstacles like finding practical materials to use will be sidestepped once they understand more about the way the science works.

One drawback to the system is that while a lot of charge will move into the channel between materials with a slight change in voltage, it moves slowly.  They said this could be fixed by using purer samples. 

"It's not going to revolutionize electronics tomorrow," MIT Professor of Physics Raymond Ashoori, who led the research, said in a statement. "But this mechanism exists, and once we know it exists, if we can understand what it is, we can try to engineer it."

They have reported their initial results in the journal Science.


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