Application of superconductor?semiconductor Schottky barrier for electron cooling

Savin, A. M.; Prunnila, Mika; Ahopelto, Jouni; Kivinen, P.; Törmä, Païvi; Pekola, Jukka P.

doi:10.1016/s0921-4526(02)02400-6

Cited by 10 publications

(12 citation statements)

References 8 publications

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“…Earlier SOI coolers with a higher dopant concentration of 6.7 Â 10 19 cm À3 (and volume 0.87Â smaller) showed similar cooling to our control sample with an optimum T min / T b of about 0.77 at 250 mK. 5 We have modeled the cooling power P c and current I in our devices using equations 7,12…”

mentioning

confidence: 67%

“…4 The Schottky barrier resistance was reduced by increasing the dopant concentration (1.8 kX lm 2 for a dopant concentration of 1.6 Â 10 20 cm À3 ), but this approach led to an additional heating mechanism which was most dominant at low bath temperatures. 5 The heating effect was attributed to sub-gap leakage, local phonon heating, and back tunneling of quasiparticles from the superconductor. 5-7 Similar heating effects have also been attributed to states in the superconductor band gap and to non-equilibrium effects.…”

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confidence: 99%

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Strain enhanced electron cooling in a degenerately doped semiconductor

Prest

Muhonen

Prunnila

et al. 2011

Applied Physics Letters

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Enhanced electron cooling is demonstrated in a strained-silicon/superconductor tunnel junction refrigerator of volume 40 um^3. The electron temperature is reduced from 300 mK to 174 mK, with the enhancement over an unstrained silicon control (300 mK to 258 mK) being attributed to the smaller electron-phonon coupling in the strained case. Modeling and the resulting predictions of silicon-based cooler performance are presented. Further reductions in the minimum temperature are expected if the junction sub-gap leakage and tunnel resistance can be reduced. However, if only tunnel resistance is reduced, Joule heating is predicted to dominate.Comment: 3 pages, 5 figure

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confidence: 67%

mentioning

confidence: 99%

Strain enhanced electron cooling in a degenerately doped semiconductor

Prest

Muhonen

Prunnila

et al. 2011

Applied Physics Letters

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“…Furthermore, relatively large subgap currents are typically observed leading to non-ideal cooler performance. The cooling effect in S-Sm structures was first presented in [83] and extended in [84,85]. In [83], a cooling power of roughly 0.5 pW was achieved with two 5x18 µm 2 junctions having total R T of 800 Ω.…”

Section: Schottky Barrier Coolersmentioning

confidence: 99%

Micrometre-scale refrigerators

2012

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A superconductor with a gap in the density of states or a quantum dot with discrete energy levels is a central building block in realizing an electronic on-chip cooler. They can work as energy filters, allowing only hot quasiparticles to tunnel out from the electrode to be cooled. This principle has been employed experimentally since the early 1990s in investigations and demonstrations of micrometre-scale coolers at sub-kelvin temperatures. In this paper, we review the basic experimental conditions in realizing the coolers and the main practical issues that are known to limit their performance. We give an update of experiments performed on cryogenic micrometre-scale coolers in the past five years.

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“…However, it turned out that the high transparency (low resistance) Sm-S junctions that are needed for efficient coolers, did not behave according to the expectations 16 17 . They suffered from significant sub-gap leakage, which can be described phenomenologically by smearing of the ideally sharp density of states in the superconductor (see Fig.…”

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confidence: 98%

Interfacial Engineering of Semiconductor–Superconductor Junctions for High Performance Micro-Coolers

Gunnarsson

Richardson-Bullock

Prest

et al. 2015

Sci Rep

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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.

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Application of superconductor?semiconductor Schottky barrier for electron cooling

Cited by 10 publications

References 8 publications

Strain enhanced electron cooling in a degenerately doped semiconductor

Strain enhanced electron cooling in a degenerately doped semiconductor

Micrometre-scale refrigerators

Interfacial Engineering of Semiconductor–Superconductor Junctions for High Performance Micro-Coolers

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