Researchers unveil single-molecule transistor
By siliconindia   |   Thursday, 24 December 2009, 18:36 IST   |    7 Comments
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Bangalore: Traditionally, a transistor is made up of two electrodes, a source and a sink, and a gate to control the flow of current between them, now a new type of transistor designed by an international team of researchers can revolutionize the way transistors work. The team has unveiled a single molecule transistor that can respond to a gate voltage just like the traditional semiconductors do. In semiconductor transistors, the gate contains a semiconductor and another electrode. Altering the voltage in this electrode controls whether current can flow across the semiconductor between the source and sink, reports Nature. For molecular transistors, the semiconductor is replaced by a single molecule. In such a system electrons can flow through a variety of molecules, but controlling that process is not easy. A few of the past efforts have switched currents on and off by changing the charge on the molecule or playing with the spin of the electrons that pass through it. However, these are difficult challenges in their own right, and far more complex than simply applying a voltage to the gate. The researchers used a process for creating a nanoscale gap in a gold wire that was placed directly above an aluminum oxide electrode that controls the gate. The gold had been covered with one of two types of molecules in advance and, once the gap was created, there was a chance that one of those molecules dropped into the newly vacated space, bridging the gap and enabling the molecule to conduct currents between the two gold electrodes. The team used two different types of molecules for the transistor to work. Where this new research doesn't vary from past work is that high failure rate during production. Out of 418 devices they produced, only 35 behaved as if a molecule had fallen into place in the gate once the gap between its electrodes was created.

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