Imaging the sensitivity inhomogeneities of diamond detectors

Diamond is a semiconducting material which can withstand high temperatures, a wide range of corrosive environments and exhibits high radiation hardness. This combination of properties makes it extremely attractive for use as photon and particle detectors. The ESRF ID21 SXM has been used to image the spatial variations of detector sensitivity over a range of both natural and Chemical Vapour Deposited (CVD) diamond devices. The measurements are performed by mapping the photon-induced current flow of the biased detectors. Evaluation of the sensitivity inhomogeneities are of dual interest; For detection applications involving relatively small beams it is important that the device response be as uniform as possible. Furthermore, from a fundamental aspect, the understanding of the origin of the sensitivity variations can be a route, for example in CVD materials, to modifying the growth and processing parameters in order to produce improved devices. This paper demonstrates an application of alternative detection modes in X-ray microscopy for a problem of technological interest. Moreover, it shows how the flexible control of the primary X-ray penetration depth by varying the probe energy permits an evaluation of the relative influence of the surface and bulk material