Extremely weak sub-kelvin electron–phonon coupling in InAs on Insulator

We are proposing, as an ideal candidate for caloritronic devices operating at subkelvin temperatures, a hybrid superconductor–semiconductor platform named InAs on insulator (InAsOI). This heterostructure is made by doped InAs grown on an insulating buffer of InAlAs on a GaAs substrate. Caloritronic devices aim to heat or cool electrons out of equilibrium with respect to the phonon degree of freedom. However, their performance is usually limited by the strength of the electron–phonon (e–ph) coupling and the associated power loss. Our work discusses the advantages of the InAsOI platform, which are based on the significantly low e–ph coupling measured compared to all-metallic state-of-the-art caloritronic devices. Our structure demonstrates values of the e–ph coupling constant up to two orders of magnitude smaller than typical values in metallic structures.