極低温電子デバイスにおける熱放散機構

Electronics that operate at extremely low temperatures dissipate heat via a different mechanism than conventional electronics, reports a study in Nature Materials. This is the first observation of this mechanism, which results in significant self-heating, and could potentially impact the ultimate sensitivity achievable in cryogenic electronics, such as those used on space crafts.

Such cryogenic electronics are used in high-accuracy low-energy and low-noise applications and understanding how their components dissipate heat is of paramount importance, as both heat dissipation and mechanisms of self-heating can result in the degradation of a device’s performance. Under normal circumstances, and at a temperature of approximately 25 degrees Celsius, heating causes the crystals, which make up electronic components, to vibrate. Heat escapes through the damping of these vibrations at defects and interfaces of the crystals.

Austin Minnich and colleagues find that, at the very low temperatures achieved in cryogenic electronics (approximately -260 degrees Celsius), heat dissipation occurs by a completely different mechanism, called ‘phonon black-body radiation’. Phonon black-body radiation occurs when vibrations, caused by heating, emit radiation without any interaction with the crystals. This newly observed mechanism of heat dissipation results in considerable self-heating, which limits the minimum temperature that these electronics can operate at. This then limits the minimal achievable sensitivity of cryogenic electronic devices.