Thermionic junction devices utilizing phonon blocking

Abstract

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.

Interplay of electron and phonon channels in the refrigeration through molecular junctions

“…In this section we provide estimates for the temperature reduction that can be reached in real devices based on a simple electro-thermal circuit. To do so, we base our discussion on the experimental setup which was used to measure the charge and heat transport for one of the molecular junctions (OPE3-Ph) used in this study 34,35 . In the experiment, a microelectro-mechanical system (MEMS) was suspended using four silicon nitride beams.…”

“…We model this setup with the electro-thermal circuit as shown in Fig. 8, which was inspired by a similar model for a semiconductor-superconductor thermionic junction 35 , where the quasiparticle gap gives similar energy filtering as the HOMO-LUMO gap in this work.…”

Superconducting tunnel junction fabrication on three-dimensional topography via direct laser writing

“…Other possible applications of NIS junctions are in metrology [25,26], thermal rectification [27] and electronic cooling [28,29], with demonstrations of cooling of macroscopic and mesoscopic platforms [30][31][32], nanoscale beams [33,34], radiation detectors [35], remote devices via photons [36,37] and quantum information circuit components [38].…”

Cascaded superconducting junction refrigerators: optimization and performance limits

“…Recently, the electronic refrigeration of a macroscopic silicon chip was demonstrated using aluminium-silicon junctions as the electronic cooling element, mechanical support, and as a blockade for phonon heat transport [13]. Phonon transport was suppressed simply by the Kapitza resistance between Al and Si [14].…”

“…1(a). Reference [13] concludes that refrigeration from above 1 K to below 100 mK is a realistic target, but improvements are still needed: (i) Since both cooling power and phonon heat leaks are proportional to the tunnel junction area A, it is beneficial to decrease the characteristic resistance R A = R T A to improve the ratio between cooling power and phonon heat leaks.…”