Soft X-ray performance of superconducting tunnel junction arrays

A number of 6/spl times/6 element arrays of Ta-based superconducting tunnel junctions have been manufactured for photon counting applications with moderate energy resolution in ground-based optical astronomy. The individual array elements show low leakage, uniform responsivity across the array, good simultaneous Josephson current suppression and minor crosstalk between adjacent pixels. The same arrays have been characterized in the soft X-ray range (E=270-1500 eV). The base electrode response shows good energy resolving power (E//spl Delta/E/spl ap/140). Unwanted spectral features originating from other parts of the detector can be largely eliminated by rise-time filtering. Modifications in the layering are necessary in order to improve the soft X-ray detection efficiency.