The First Steps in Solid-State X-Ray Imaging.

The construction of an alternative to medical x-ray film is required to effect a reduction in the dose of ionising radiation delivered to the population without reducing the diagnostic efficacy of the method. An electronic alternative to medical x-ray films requires the use of materials which combine the ability to efficiently absorb x-rays with the ability to behave as semiconductors. Semiconductors with good charge transport properties and high room temperature resistivities. This is an uncommon combination. Two materials, cadmium telluride and cadmium zinc telluride, are among the very few semiconductors that do possess these characteristics. A maturing fabrication technology is now supplying these semiconductors in forms that approach the theoretical behaviour of defect free material. This thesis looks at the behaviour of spectroscopic grade CdZnTe detectors, in terms of electronic properties and construction. The interaction of x-rays, infra-red radiation, polarised light and heat on these detectors was investigated in order to elucidate their basic structure. From this it was concluded that CdZnTe in some form and with the appropriate electrical contacts could provide the high performance required of any alternative to medical x-ray film