Question

what is coplanar design in radiation detectors

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Answer 1

coplanar design in radiation detectors:

Most ionization based radiation detectors–gas ion chambers, liquid ionization detectors, and compound semiconductor detectors–suffer from poor collection of charge carriers of one polarity type. As a result, detector energy resolution is severely degraded when a basic parallel electrode detector geometry is used.

  The coplanar-grid charge sensing technique provides a method for improving the spectral response of gamma-ray detectors based on compound semiconductors, which typically have poor charge transport properties.

Traditionally, in gas and liquid detectors, a suspended grid electrode structure (Frisch grids) that preferentially senses the collection of one carrier type has been successfully employed to overcome this problem. However, this technique cannot be readily applied to semiconductor detectors because of difficulties in producing the required grid electrode structure inside the semiconductor crystals.

   The effectiveness of this technique however can be compromised by non-uniform charge induction characteristics across the detector. This paper examines such non-uniformity due to fringe effects near the detector edges.