Scanning Acoustic Microscopy and SIMS investigation of CdTe detectors

The performance of both CdTe and CZT detectors depend largely on the quality of the contacts as well as on the surface preparation procedures. In general, electroless deposition contacts of either Au or Pt are used to prepare nearly ohmic contacts. These contacts are rather complicated in their structure and often failures or instabilities are observed. In this paper, we have investigated these surface areas by scanning acoustic microscopy, a method which is used for the first time to our knowledge to characterise these contact layers. By measuring the acoustic signal at various points of contacted samples, information on the surface uniformity can be obtained. These measurements have been complemented by SIMS measurements, giving the chemical distribution in the near-surface region of the elements of interest.