Photoconductive Position Sensitive CVD Diamond Detectors

Abstract

Different contact structures were studied to realize CVD-diamond sensors able to detect light beam displacements. Photons irradiate the sample backside where a mesh contact is used for device biasing. Photogenerated carriers are collected at the top-side where metal strip lines are realized. Depending on the layout of such contacts, beam displacement is measured by means of the elaboration of acquired strip signals. A very compact front-end electronics was used for signal conditioning. As for an image sensor array, the signal of each strip is integrated in the same time-period. Analog to digital conversion is performed in a second time period by means of high-resolution σ-δ converters and digital filtering. During such a second time-period, strip line photocurrents are integrated by a second set of ideal integrators allowing signal acquisition in a continuous-mode fashion. Limited by the 500 μs conversion time of ADCs, the detection system allows up to 2 kSPS data output acquisition rate.