Technology development of 3D detectors for medical imaging

Fabrication routes to realising ‘3D’ detectors in gallium arsenide have been investigated and their electrical characteristics measured. The geometry of the detector is hexagonal with a central anode surrounded by six cathode contacts. This geometry gives a uniform electric field with the maximum drift and depletion distance set by electrode spacings rather than detector thickness. The advantages of this structure include short collection distances, fast collection times and low depletion voltages depending on the electrode diameter and pitch chosen. These characteristics are fundamental for the application of 3D detectors in, for example, medical imaging and protein crystallography.