Thermionic junction devices utilizing phonon blocking

Emma Mykkänen, Janne S. Lehtinen, Leif Grönberg, Andrey Shchepetov, Andrey V. Timofeev, David Gunnarsson, Antti Kemppinen, Antti J. Manninen, Mika Prunnila (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)


Electrothermal elements are used in various energy harvesters, coolers, and radiation detectors. The optimal operation of these elements relies on mastering two competing boundary conditions: the maximization of the electrothermal response and the blockade of lattice (phonon) thermal conduction. In this work, we propose and demonstrate that efficient electrothermal operation and phonon blocking can be achieved in solid-state thermionic junctions, paving the way for new phonon-engineered high-efficiency refrigerators and sensors. Our experimental demonstration uses semiconductor-superconductor (Sm-S) junctions where the electrothermal response arises from the superconducting energy gap and the phonon blocking results from the acoustic transmission bottleneck at the junction. We demonstrate a cooling platform where a silicon chip, suspended only from the Sm-S junctions, is cooled by ~40% from the bath temperature. We also show how the observed effect can be used in radiation detectors and multistage electronic refrigerators suitable for cooling of quantum technology devices.

Original languageEnglish
Article numbereaax9191
JournalScience advances
Issue number15
Publication statusPublished - 2020
MoE publication typeA1 Journal article-refereed


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