Thermal Conductance Measurements of a Micron-Sized Transition-Edge Hot-Electron Micro-Bolometer

Future ground and space-based astronomy missions in the millimeter and sub-millimeter range will rely upon kilopixel detector arrays. We are developing a superconducting Transition-Edge Hot-Electron Bolometer (THM) for use in these next generation missions. Thermal isolation of the THM is controlled by the hot-electron effect between the electrons and phonons within the small volume of the superconducting detector. To reach noise levels near the photon background noise for observing the Cosmic Microwave Background (CMB) and the submillimeter and far-infrared background the optimal detector size occurs at the micron length scale. We present measurements of the thermal conductance of two micron-sized THM devices which show a hot-electron temperature dependence and predict NEP ≤ 5 × 10^-18 W/√{Hz} for CMB loading conditions and NEP ≤ 1 × 10^-19 W√{Hz} in the low power loading limit. We also briefly discuss the detector geometry and thermal conductance optimization for CMB loading conditions.