This article is cited in 6 papers

The influence of the diffusion cooling on the noise band of the superconductor NbN hot-electron bolometer operating in the terahertz range

I. V. Tret’yakov^ab, N. S. Kaurova^a, B. M. Voronov^a, V. A. Anfertev^b, L. S. Revin^b, V. L. Vaks^b, G. N. Gol'tsman<sup>a

a</sup> Moscow State Pedagogical University
^b Institute for Physics of Microstructures, Russian Academy of Sciences, Nizhnii Novgorod

Abstract: Results of an experimental study of the noise temperature $(T_n)$ and noise bandwidth (NBW) of the superconductor NbN hot-electron bolometer (HEB) mixer as a function of its temperature $(T_b)$ are presented. It was determined that the NBW of the mixer is significantly wider at temperatures close to the critical ones $(T_c)$ than are values measured at 4.2 K. The NBW of the mixer measured at the heterodyne frequency of 2.5 THz at temperature $T_b$ close to $T_c$ was $\sim$13 GHz, as compared with 6 GHz at $T_b$ = 4.2 K. This experiment clearly demonstrates the limitation of the thermal flow from the NbN bridge at $T_{b}\ll T_{c}$ for mixers manufactured by the in situ technique. This limitation is close in its nature to the Andreev reflection on the superconductor/metal boundary. In this case, the noise temperature of the studied mixer increased from 1100 to 3800 K.

Received: 10.12.2015

 English version: Technical Physics Letters, 2016, 42:6, 563–566

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