Until now, the ability to make electronic devices faster has come down to a simple principle: scaling down transistors and other components. But this approach is reaching its limit, as the benefits of shrinking are counterbalanced by detrimental effects like resistance and decreased output power.
Elison Matioli of the Power and Wide-band-gap Electronics Research Lab (POWERlab) in EPFL's School of Engineering explains that further miniaturization is therefore not a viable solution to better electronics performance. "New papers come out describing smaller and smaller devices, but in the case of materials made from gallium nitride, the best devices in terms of frequency were already published a few years back," he says. "After that, there is really nothing better, because as device size is reduced, we face fundamental limitations. This is true regardless of the material used."
In response to this challenge, Matioli and PhD student Mohammad Samizadeh Nikoo came up with a new approach to electronics that could overcome these limitations and enable a new class of terahertz devices. Instead of shrinking their device, they rearranged it, notably by etching patterned contacts called metastructures at sub-wavelength distances onto a semiconductor made of gallium nitride and indium gallium nitride. These metastructures allow the electrical fields inside the device to be controlled, yielding extraordinary properties that do not occur in nature.
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