A fast infrared detector based on patterned YBCO thin film

Detectors for infrared radiation (λ = 0.85 μ m) were made of 50 nm thick YBa2Cu3O7-δ films on LaAlO3 and MgO or 60 nm thick films on NdGaO3. Parallel strips (1 μ m wide by 20 μ m long) were patterned in the films and formed the active device. These devices were designed to detect short infrared laser pulses by electron heating. The detectors were current biased into the resistive and the normal states. The response was studied in direct pulse measurements as well as by amplitude modulation of a laser. The pulse measurements showed a fast picosecond response followed by a slower decay related to phonon escape through the film-substrate interface and heat diffusion in the substrate. The frequency spectra up to 10 GHz showed two slopes with a knee corresponding to the phonon escape time. (author)