Capacitively Coupled Hot-Electron Microbolometer as a Perspective IR and Sub-mm Wave Sensor

L. S. Kuzmin

Published Mar 1, 1998• 1 citation

Abstract

normal metal strip at low temperatures (so called electron effect) to produce a large A novel concept of the normal-metal hotelectron bolometer using capacitive coupling of the absorber to antenna (NHEB-CC) has been proposed. The concept is based on the normal metal hot-electron microbolometer with Andreev mirrors (NHEB-A) using a SIN junction as a temperature sensor [1-3]. The NHEB-A technology brings a possibility to fabricate the sub-mm wave receiver for space applications with a noise equivalent power NEP about 3x1 0' 8 W/Hz at 100 mK. However, the Andreev mirrors could give certain frequency limitations for using this bolometer for higher frequencies with the energy quantum hf higher than the energy of a superconducting gap A. The NHEB-CC technology with capacitive coupling of the absorber to antenna avoids these problems. The effective high frequency coupling of the external signal in NHEB-CC is achieved by a low impedance of the coupling capacitances. At the same time, the capacitance gives reliable protection against escaping the hot electrons from the absorber. Usual tunnel junctions with proper thickness of the barrier can be used as capacitors. In such realization, we keep the main advantage of the NHEB technology very small thermal conductance between electrons and phonons due to small volume of an absorber (typical value of G is 2x10 W/K for T=100 mK) in combination with frequency independent protection of the absorber against thermal leak to the antenna.

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