Recent progress in HTSC bolometric and nonbolometric detectors

The main phenomena that may be responsible of radiation detecting mechanisms in superconductors are described in a first part of this paper. Several examples are given, ranging from broadband and sensitive bolometric devices to ultrafast nonbolometric infrared detectors. The second part is devoted to the study of various transition edge bolometers designed to be built at low cost. Polycrystalline zirconia substrates have been used, to grow YBCO films by both in situ and ex situ oxygenation after radiofrequency sputtering. The voltage responsivity at 10.6 micrometers wavelength has been studied with respect to the modulation frequency of the incident radiation, both experimentally and theoretically. A 2D thermal model has been developed, allowing to interpret the complex (amplitude and phase) experimental frequency responses of various devices. In particular, the amplitude response can be described as a succession of f-1 and F-1/2 segments. Noise measurements show NEP and detectivity values reaching a very satisfactory level for granular films.