in the wake of the recent news about the samsung galaxy note 7 and its thermal runaway issues that have forced the company to a costly shut down of production, mit researchers have released a new report in nature communications that may leads to a possible explanation for overheating issues in high component density products, such as smartphones.

(wikimedia commons)

based on experiments using laser pulses measuring the interaction of atomic particles in a silicon wafer, the researchers have seen that as the number of electrons increased in the wafer, they scattered heat-carrying particles known as phonons, which limited the phonons’ ability to dissipate heat.

according to a story on phys.org, “scientists have long studied the effect of such electron-phonon interactions on electrons themselves, but how these same interactions affect phonons—and a material's ability to conduct heat—is less well-understood.”

the abstract for the mit report reads:

“there is a growing interest in the mode-by-mode understanding of electron and phonon transport for improving energy conversion technologies, such as thermoelectrics and photovoltaics. whereas remarkable progress has been made in probing phonon–phonon interactions, it has been a challenge to directly measure electron–phonon interactions at the single-mode level, especially their effect on phonon transport above cryogenic temperatures.

“here we use three-pulse photoacoustic spectroscopy to investigate the damping of a single sub-terahertz coherent phonon mode by free charge carriers in silicon at room temperature. building on conventional pump–probe photoacoustic spectroscopy, we introduce an additional laser pulse to optically generate charge carriers, and carefully design temporal sequence of the three pulses to unambiguously quantify the scattering rate of a single-phonon mode due to the electron–phonon interaction.

“our results confirm predictions from first-principles simulations and indicate the importance of the often-neglected effect of electron–phonon interaction on phonon transport in doped semiconductors.”

read analysis of the mit report at http://phys.org/news/2016-10-particle-collisions-overheated-circuits-thermoelectric.html.

the full report, “photo-excited charge carriers suppress sub-terahertz phonon mode in silicon at room temperature” can be found at http://www.nature.com/articles/ncomms13174.