Modeling and optimization of high-T c superconducting bolometers: The effect of film thickness

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Abstract
The performance of thin‐film, YBa2Cu3O7−x‐based, transition edge bolometers at high and moderate degrees of thermal isolation has been modeled. Using standard formulas in connection with a parametrized representation of available empirical data, i.e., transition temperature Tc, resistance temperature coefficient β, and resistivity ρ, both the detectivity D* and responsivity ‖S‖ of the detectors have been evaluated as a function of film thickness d. The model calculations reveal that ‖S‖ scales inversely with film thickness and conductivity, respectively, and peaks at a thickness of approximately 100 Å. In turn, the detectivity D* degrades rapidly for smaller values, suggesting to compromise on both figures in the same range. These results, in part, rely on recent findings on flicker noise in thin metal films, as discussed in the literature. The model also shows that the performance at moderate degrees of thermal isolation compares well with existing thermal detectors operating at ambient temperature, but is expected of being superior for small, fast detector configurations at high degrees of thermal isolation.