Nano-switches made out of graphene could make our electronics even smaller. For the first time, physicists have built reliable, efficient graphene nanomachines that can be fabricated on silicon chips. They could lead to even greater miniaturization.
“Chances are that you own a microelectromechanical device—probably dozens of them. These devices fill the modern world. They make possible the accelerometers in smartphones, the microphones in laptops, and the micromirrors in digital projectors, to name just a few.
They are typically a few micrometers in size, tiny by any standards. But scientists and engineers want them even smaller—on the nanometer scale, if possible. At that size, these machines can work as simple switches in logic and memory devices, raising the prospect of more powerful and more efficient data-processing devices.
These micromachines are generally carved into silicon chips. But as they get smaller, silicon switches become less efficient because they leak current when they are off. A better option is a graphene switch, which is easy to carve on a nanometer scale and relatively straightforward to build into conventional silicon chips. Neither does it leak current when it is off.
But there is a problem. When graphene touches silicon, it tends to stick fast. Imagine a switch consisting of a flexible graphene bar that forms a circuit when the bar touches a silicon electrode. If the bar sticks to the electrode, it cannot be switched off again.
This problem is known as stiction. And despite significant financial investment in graphene research by governments all over the world, nobody has found a good way to solve it.
Enter Kulothungan Jothiramalingam at the Japan Advanced Institute of Science and Technology and colleagues, who have found a solution. Using it, they have created graphene-based nanoelectromechanical devices that can act as switches and even as logic gates.
Their method is straightforward. They coat a silicon chip with nanocrystalline graphene, which sticks fast to the surface. Then they cover this with a layer of hydrogen silsesquioxane, which acts as a resist and can be carved into various shapes. On top of this they place another layer of graphene.”…
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Source: MIT Technology Review
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