%0 Journal Article
%T Nb–Au bilayer hot-electron bolometers for low-noise THz heterodyne detection
%A Siddiqi, I.
%A Prober, D. E.
%J Applied Physics Letters
%D 2004
%V 84
%N 8
%@ 0003-6951
%F Siddiqi+Prober2004
%O exported from refbase (https://db.rplab.ru/refbase/show.php?record=571), last updated on Sun, 05 Apr 2009 18:18:46 -0500
%X The sensitivity of present Nb diffusion-cooled hot-electron bolometer (HEB) mixers is not quantum limited, and can be improved by reducing the superconducting transition temperature TC. Lowering TC reduces thermal fluctuations, resulting in a decrease of the mixer noise temperature TM. However, lower TC mixers have reduced dynamic range and saturate more easily due to background noise. We present 30 GHz microwave measurements on a bilayer HEB system, Nb–Au, in which TC can be tuned with Au layer thickness to obtain the maximum sensitivity for a given noise background. These measurements are intended as a guide for the optimization of THz mixers. Using a Nb–Au mixer with TC = 1.6 K, we obtain TM = 50 K with 2 nW of local oscillator (LO) power. Good mixer performance is observed over a wide range of LO power and bias voltage and such a device should not exhibit saturation in a THz receiver.
%K HEB
%K mixers
%K dynamic range
%K saturation
%K LO power
%K local oscillator power
%K Nb
%R 10.1063/1.1646726
%U http://link.aip.org/link/APPLAB/v84/i8/p1404/s1&Agg=doi
%U https://doi.org/10.1063/1.1646726
%P 1404