Geometry effects on the response of a superconducting tunnel junction detector

Superconductive tunnel junction detectors are promising as next generation X-ray detectors. By means of Low Temperature Scanning Electron Microscopy, the inhomogeneities in the response of this type of detectors are investigated. Spatial variations in the quasiparticle life time and the quasiparticle tunnel time are reasons for inhomogeneity in the response. Junctions with two different counter electrode geometries were compared. It is shown that the response homogeneity of a junction with a wiring layer fully covering the counter electrode is better than the response of a junction in which the counter electrode is contacted by means of a contact pad. (author)