Signal generation in CdTe X-ray sensors

This write-up explains the signal generation mechanism in CdTe semiconductor sensors. Derivations are mostly carried out explicitly, starting with basic semiconductor relations. The analysis is largely applicable to any semiconductor, with the focus being on the Schottky-type CdTe:Cl sensors that are employed in the Spectrometer/Telescope for Imaging X-rays (STIX) instrument on-board the ESA Solar Orbiter mission.