Speaker
Description
Single and four-quadrant (4Q) photodiodes are very common beam intensity and position diagnostic devices for hard X-ray synchrotron beamlines, and they are also of interest for real time monitoring and dosimetry in particle therapy medical applications. Ultrathin Si devices are advantageous in terms of cost and sensing area compared to diamond standard. X-ray beam position monitors, are to be thinner than 10 μm when made of silicon to achieve X-ray transmission higher than 90% for photon energies above 10 keV. Owing to their lower dark current, lower susceptibility to temperature and visible light conditions, and potential radiation hardness, there is also interest in silicon carbide (SiC) for some of these applications.
In this work, an extensive study involving physical and electrical characterization, as well as radiation effects, is carried out on single and 4Q photodiodes fabricated on ultrathin (10 μm, 5 μm and 3 μm) Si films from Silicon-on-Insulator (SOI) substrates, as well as on 1-2 μm-thick Si membranes obtained by chemical back-etching of high resistivity (HR) Float Zone (FZ) bulk Si substrates. Furthermore, 4Q devices fabricated on 5 μm-thick semi-insulating SiC epitaxial layers on bulk 4H-SiC substrates are also studied. Finally, the performance of the devices as radiation detectors is investigated by means of laser beam scanning transient current technique (TCT) and X-ray test beam at XALOC beamline of ALBA Synchrotron in Cerdanyola del Vallès (Barcelona).
