Interfacial engineering of semiconductor-superconductor junctions for high performance micro-coolers

D. Gunnarsson, J.S. Richardson-Bullock, M.J. Prest, H.Q. Nguyen, Andrey Timofeev, V.A. Shah, T.E. Whall, E.H.C. Parker, D.R. leadley, M. MYronov, Mika Prunnila

    Research output: Contribution to journalArticleScientificpeer-review

    11 Citations (Scopus)


    The control of electronic and thermal transport through material interfaces is crucial for numerous micro and nanoelectronics applications and quantum devices. Here we report on the engineering of the electro-thermal properties of semiconductor-superconductor (Sm-S) electronic cooler junctions by a nanoscale insulating tunnel barrier introduced between the Sm and S electrodes. Unexpectedly, such an interface barrier does not increase the junction resistance but strongly reduces the detrimental sub-gap leakage current. These features are key to achieving high cooling power tunnel junction refrigerators, and we demonstrate unparalleled performance in silicon-based Sm-S electron cooler devices with orders of magnitudes improvement in the cooling power in comparison to previous works. By adapting the junctions in strain-engineered silicon coolers we also demonstrate efficient electron temperature reduction from 300?mK to below 100?mK. Investigations on junctions with different interface quality indicate that the previously unexplained sub-gap leakage current is strongly influenced by the Sm-S interface states. These states often dictate the junction electrical resistance through the well-known Fermi level pinning effect and, therefore, superconductivity could be generally used to probe and optimize metal-semiconductor contact behaviour.
    Original languageEnglish
    Article number17398
    Number of pages10
    JournalScientific Reports
    Issue number5
    Publication statusPublished - 2015
    MoE publication typeA1 Journal article-refereed


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