As chip dimensions have decreased to match the demands of Moore’s Law, insulating materials separating the transistor gate from the channel below it have had to be thinned down so much that keeping current from leaking through has been difficult. In fact, chipmakers are no longer thinning the gate oxide, and it stands now at 1 nanometer in thickness because to go thinner would allow too much current to flow through the channel when the transistor is supposed to be turned off.
Researchers at Stanford University have been running simulations with some two-dimensional materials that when sandwiched together can switch the material between conducting and insulating just by tugging on its edges. If physical experiments on the material are successful, it could provide a way to completely shut down the leakage of current in chips and still go to smaller chip dimensions.
The researchers believe that if the material could be used in today's smart phone processors it could reduce their power consumption considerably.
The work, which was published in the journal Nature Communications, represents a growing body of knowledge on so-called transition dichalcogenide metals, which are materials that combine one of 15 transition metals with one of three members of the chalcogen family: sulfur, selenium, or tellurium.
In the computer models, the Stanford researchers took one atomic layer of molybdenum atoms and sandwiched it between two atomic layers of tellurium atoms. In the video below, you can see the three-atom thick structure switch between conductor and an insulator as it us pulled.
It does make an attractive computer model. However, whether it can be translated into an actual physical material remains to be seen. Even if they can produce the three-atom-thick sandwich, it’s not clear whether it could really be developed for large-scale production. While physical experiments have successfully demonstrated single-atom transistors, many are questioning whether such a device could ever be be made by the millions or billions.
It’s not clear that a now three-year-old challenge of Professor Mike Kelly at Cambridge University has ever been sufficiently answered. In the challenge he argues that devices with dimensions less than three nanometers cannot be mass produced using a top-down manufacturing technique. Until that question is adequately addressed, we may have here just another computer model that could lead to a physical material but not one that could be used in the mass production of electronic devices.
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.