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

11 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 - Apr 2020
MoE publication typeA1 Journal article-refereed


This work was financially supported by H2020 FET-open project EFINED (project number 766853), H2020 program project MOS-QUITO (project number 688539) and Academy of Finland project QuMOS (project numbers 288907 and 287768). E.M. acknowledges support from the Jenny and Antti Wihuri Foundation. This work was performed as part of the Academy of Finland Centre of Excellence program (QTF Centre of Excellence, project 312294).


Dive into the research topics of 'Thermionic junction devices utilizing phonon blocking'. Together they form a unique fingerprint.

Cite this