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    More overheating problems loom large as devices shrink

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    Lithium-ion batteries are on the hot seat following reports of explosions and fires caused by the power packs in Samsung Electronics Note 7 smartphones.

    But according to a new MIT study reported by eengineering.com, potential heat problems with electronic devices are lurking even deeper, inside semiconductor devices themselves. The study suggests that as electron concentrations rise due to the ever-decreasing size of transistors, electronic devices of all kinds may face an increasingly high risk of overheating.

    The problem is exacerbated by consumer demand for ever more powerful devices which is pushing engineers to adopt bigger screens and more powerful processing devices that require packing more energy, and circuitry, into smaller spaces.

    Overheatings is going to be “a really serious problem”  when the scale of circuits becomes smaller, the MIT researchers caution.

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    As transistors size decreases, electron concentration increases, and phonons become less effective in carrying out heat. (Image courtesy of MIT.)

    Study Finds Increasing Risk of Electronics Overheating

    A new study conducted by MIT engineers has revealed that interactions between electrons and phonons in computer chips may play a larger role in affecting heat dissipation than previously thought. The study suggests that as electron concentrations rise due to the ever-decreasing size of transistors, electronic devices may face an increasingly high risk of overheating.

    Three-Pulse Photoacoustic Spectroscopy

    Previous experiments have shown that semiconductors with high electron concentrations have a reduced capacity to dissipate heat. However, it was assumed that this reduction was due to material defects arising from doping.

    The new study began with calculations that showed an alternative explanation. The researchers showed that in silicon, when the electron concentration is above 1019 e-/cm3, electron-phonon interactions would strongly scatter the phonons and reduce the ability of the material to dissipate heat. This reduction would climb as high as 50 percent when the concentration reaches 1021 e-/cm3.

    The next step was to verify these findings, which presented something of an experimental challenge. Lead researcher Bolin Liao explained: “…the challenge to verify our idea was, we had to separate the contributions from electrons and defects by somehow controlling the electron concentration inside the material, without introducing any defects.”

    The team solved this problem by expanding on a conventional technique called two-pulse photoacoustic spectroscopy. In this technique, you shine two precisely tuned lasers on a material; one which generates a photon pulse and another which measures the pulse as it scatters.

    More: here