Nowadays, low temperature superconducting hot electron bolometers (LTSC HEBs) are performing really well in the submillimeter wave range. Planar technologies are feasible that can be used for combining bolometer and antenna structures. High temperature superconducting (HTSC) films could also become the next to be used, although it seems that HTSC HEBs cannot reach their LTSC counterparts because of different phonon dynamics. In some previous models, it has been shown, however, that HTSC HEBs should be able to compete with traditional photoconductive detectors in terms of sensitivity. As the substrate temperature was assumed to be constant in these models, we wish to introduce in this paper a more detailed formulation where an extra cooling process (through the substrate) is taken into account. In a first part, simple heat propagation through the substrate is simulated to confirm the theory. The whole detector performance is analyzed in a second part, through a three-temperature model, for different device critical dimensions and thermal parameters. The influence of these characteristics on the lower cutoff frequency and on the maximal responsivity is then discussed. Different ways to improve these detectors are also given.

Superconducting hot electron bolometer mixers are now a competitive alternative to Schottky diode mixers in the terahertz frequency range because of their ultra wideband (from millimeter waves to visible light), high conversion gain, and low intrinsic noise level. High Tc superconductor materials can be used to make hot electron bolometers and present some advantage in term of operating temperature and cooling. In this paper, we present first a model for the study of superconducting hot electron bolometers responsivity in direct detection mode, in order to establish a firm basis for the design of future THz mixers. Secondly, an original process to realize YBaCuO hot electron bolometer mixers will be described. Submicron YBaCuO superconducting structures are expitaxially sputter deposited on MgO substrates and patterned by using electron beam lithography in combination with optical lithography. Metal masks achieved by electron beam lithography are insuring a good bridge definition and protection during ion etching. Finally, detection experiments are being performed with a laser at 850 nm wavelength, in homodyne mode in order to prove the feasibility and potential performances of these devices.