Charge transients locally induced by laser pulses in CdTe planar and multi-strip detectors

In detectors based on semiconductor compounds, trapping effects, material nonhomogeneities, and anomalous distribution of the internal electric field are known to affect the charge collection of the photo-generated carriers, and then the spectroscopic performance. Hence, it becomes important to use techniques able to access the local charge collection properties of the detector. To this scope an experimental set-up, which uses a collimated laser beam impinging on the detector at different positions to induce charge signal transients, has been developed. Linear scans and mapping have been performed at different voltages and the charge transients of CdTe planar and multi-strip detectors have been recorded by a proper front-end electronics. Electron and hole contributions have been identified, allowing us to extract relevant charge transport parameters.