Thermal conductance and electron-phonon coupling in mechanically suspended nanostructures

We have fabricated and characterized the principal thermal properties of a mechanically suspended nanostructure, consisting of a micron-scale suspended GaAs island, upon which we have defined superconductor-insulator-normal metal tunnel junctions. The tunnel junctions allow for sensitive thermometry and heating of the electrons in a thermally isolated normal metal element, permitting the determination of the low-temperature thermal conductance of the legs that support the GaAs island, as well as the low-temperature electron-phonon coupling. This device forms the basis of a nanoscale bolometric detector, whose optical performance can be estimated from these measurements. (C) 2002 American Institute of Physics.