Thermal relaxation in metal films limited by diffuson lattice excitations of amorphous substrates

Abstract

Here we examine the role of the amorphous insulating substrate in the thermal relaxation in thin NbN, InO${}_x$, and Au/Ni films at temperatures above 5 K. The studied samples are made up of metal bridges on an amorphous insulating layer lying on or suspended above a crystalline substrate. Noise thermometry was used to measure the electron temperature $T_e$ of the films as a function of Joule power per unit of area $P_{2D}$. In all samples, we observe the dependence $P_{2D}\propto T_e^n$ with the exponent $n\simeq 2$, which is inconsistent with both electron-phonon coupling and Kapitza thermal resistance. In suspended samples, the functional dependence of $P_{2D}(T_e)$ on the length of the amorphous insulating layer is consistent with the linear $T$-dependence of the thermal conductivity, which is related to lattice excitations (diffusons) for the phonon mean free path smaller than the dominant phonon wavelength. Our findings are important for understanding the operation of devices embedded in amorphous dielectrics.

arXiv comment9 pages, 5 figures

References in corpus (25)

• Electric Field Effect in Atomically Thin Carbon Films
• Detecting Single Infrared Photons with 93% System Efficiency
• Energy Dissipation and Transport in Nanoscale Devices
• Opportunities for mesoscopics in thermometry and refrigeration: Physics and applications
• Towards understanding two-level-systems in amorphous solids -- Insights from quantum circuits
• High Speed and High Efficiency Travelling Wave Single-Photon Detectors Embedded in Nanophotonic Circuits
• Energy dissipation in graphene field-effect transistors
• Universal origin of boson peak vibrational anomalies in ordered crystals and in amorphous materials
• Quantum breakdown of superconductivity in low-dimensional materials
• The Ioffe-Regel criterion and diffusion of vibrations in random lattices
• Energy transport in jammed sphere packings
• On the properties of superconducting planar resonators at mK temperatures
• Superconducting single-photon detectors with saturated dependence of quantum efficiency vs. bias current
• High field termination of a Cooper-pair insulator
• Electro thermal simulation of superconducting nanowire avalanche photodetectors
• Non-bolometric bottleneck in electron-phonon relaxation in ultra-thin WSi film
• Controlled integration of selected detectors and emitters in photonic integrated circuits
• Tunable sub-gap radiation detection with superconducting resonators
• Insensitivity of sub-Kelvin electron-phonon coupling to substrate properties
• Thermal properties of NbN single-photon detectors
• Kinetics of electron cooling in metal films at low temperatures and revision of the two-temperature model
• Strategy for accurate thermal biasing at the nanoscale
• Modification of electron-phonon coupling by micromachining and suspension
• Universal bottleneck for thermal relaxation in disordered metallic films
• Phonon deficit effect and solid state refrigerators based on superconducting tunnel junctions

Cited by in corpus (5)

• Self-Heating Hotspots in Superconducting Nanowires Cooled by Phonon Black-Body Radiation
• Phonon heat capacity and self-heating normal domains in NbTiN nanostrips
• Fundamental limits of few-layer NbSe${}_2$ microbolometers at terahertz frequencies
• Local bistability under microwave heating for spatially mapping disordered superconductors
• Local thermometry of NbSe${}_2$ flake with delta-$T$ noise measurements