International audienceHigh-T-C hot electron bolometers (HEB) are promising THz mixers due to their expected wide bandwidth, large mixing gain, and low intrinsic noise. To achieve this goal, 0.6-mu m-size constrictions were patterned on YBaCuO-based, 10-40-nm-thick films grown on (100) MgO substrates, which as previously reported, exhibited good DC superconducting properties. In this paper, we have simulated the DC and mixer characteristics of YBaCuO HEBs with a hot spot model usually dedicated to low-T-C devices. For a 100 nm x 100 nm x 10 nm constriction, the expected double sideband noise temperature T-N is 2000 K for 5 mu W local oscillator (LO) power (G = -13.5 dB conversion gain). For a larger (but more realistic according to YBaCuO aging effects) 600 nm x 1000 nm x 35 nm constriction, T-N = 1300 K at 200 mu W LO power (G = -12 dB). This approach is expected to allow optimizing the operation of the HEB constriction coupled to a THz planar antenna

International audienceTo investigate the THz mixing performance of YBCO hot electron bolometers (HEB), the influence of the local oscillator (LO) radiofrequency (RF) radiation has been considered in detail. As opposed to the usual hot spot modeling approach, where the LO power is assumed to be uniformly distributed over the HEB constriction length, a uniform RF current has been assumed. The local electron temperature – as obtained by solving the coupled electron and phonon thermal reservoir equations – could then be used to determine the local YBCO complex resistivity, hence the locally dissipated LO power. Besides, the use of a modified two-fluid description allowed to determine the RF-dependent temperature shift (∼ −1% THz−1) and broadening (∼ +20% THz−1) of the resistive transition. Finally, the impedance matching to the THz antenna was considered. For a typical constriction, the conversion loss and noise temperature TDSB were computed, with TDSB ∝ exp(0.32f) behavior up to 2.5 THz

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