Characterizations of electronic defects in perovskite crystals used for medical X-ray imaging

Published : 8 February 2020

The photonic systems architecture laboratory is part of the CEA LETI optronics department. We have a solid expertise in the development of new detection modules including a semiconductor or scintillator detector combined with readout electronics for X-ray or gamma imaging in the fields of medical imaging or security control.

The objective of this thesis is to study the traps levels and densities in the bandgap of a new perovskite-based semiconductor material for direct X-ray detection developed for medical radiography. Its use as photoconductive devices in matrix imagers should improve the spatial resolution of images and increase the signal, thus reducing the dose given to the patient, or even providing access to new information on tissue composition.

To reach this goal, the student, physicist and experimenter, will develop specific test bench to identify and characterize these electronic traps in the volume of crystals and at the interfaces of the devices. He will determine the nature of the defects of the thick crystalline layers developed by a doctoral student at CEA LITEN. The student will model the effect of these trap levels on the performance of the devices. In parallel, the student will study the origin of the current of darkness in perovskite devices. These results will be correlated with experimental measurements made by a doctoral student from CEA LETI. Finally, he will provide feedback on the development of crystals and devices in order to minimize the traps density and improve their overall performance.

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