No abstract

Silicon photodiodes are very useful devices as X-ray beam monitors in synchrotron radiation beamlines, as well as other astronomy and space applications. Owing to their lower susceptibility to variable temperature and illumination conditions, there is also special interest in silicon carbide devices for some of these applications. Moreover, radiation hardness of the involved technologies is a major concern for high-energy physics and space applications. This work presents four-quadrant photodiodes produced on ultrathin (10 m) and bulk Si, as well as on SiC epilayer substrates. An extensive electrical characterization has been carried out by using current-voltage (I-V) and capacitance-voltage (C-V) techniques. The impact of different temperature (from -50 ºC to 175 ºC) and visible light conditions on the electrical characteristics of the devices has been evaluated. Radiation effects caused by 2 MeV electron irradiation up to 1x10 14 , 1x10 15 and 1x10 16 e/cm 2 fluences have been studied. Special attention has been devoted to the study of charge build-up in diode interquadrant isolation, as well as its impact on interquadrant resistance. The study of these electrical properties and its radiation-induced degradation should be taken into account for device applications.

Silicon photodiodes are very useful devices as X-ray beam monitors in synchrotron radiation beamlines. Owing to Si absorption, devices thinner than 10 m are needed to achieve transmission over 90% for energies above 10 keV. In this work, new segmented four-quadrant diodes for beam alignment purposes are fabricated on both ultrathin (10 m-thick) and bulk silicon substrates. Four-quadrant diodes implementing different design parameters as well as auxiliary test structures (single diodes and MOS capacitors) are studied. An extensive electrical characterization, including current-voltage (I-V) and capacitance-voltage (C-V) techniques, is carried out on non-irradiated and gamma-irradiated devices up to 100 Mrad doses. Special attention is devoted to the study of radiation-induced charge build-up in diode interquadrant isolation dielectric, as well as its impact on device interquadrant resistance. Finally, the devices have been characterized with an 8 keV laboratory X-ray source at 10 8 ph/s and in BL13-XALOC ALBA Synchroton beamline with 10 11 ph/s and energies from 6 to 16 keV. Sensitivity, spatial resolution and uniformity of the devices have been evaluated. KEYWORDS: Beam-line instrumentation (beam position and profile monitors; beam-intensity monitors; bunch length monitors); X-ray detectors; Si microstrip and pad detectors; Radiation damage to detector materials (solid state).

The ALBA synchrotron 1 (Barcelona, Spain) is building MINERVA a new X-ray beamline designed to support the development of the ATHENA mission (Advanced Telescope for High Energy Astrophysics). The beamline design is originally based on the monochromatic pencil beam XPBF 2.0 2 at the Physikalisch-Technische Bundesanstalt (PTB), at BESSY II. MINERVA will provide metrology capabilities to integrate stacks produced by cosine company into a mirror module (MM) and characterize them. It will provide photons with a fixed energy of 1.0 keV with a residual divergence below 1 × 1 arcsec 2 rms. The beam dimensions at the mirror module is adjustable from 10 × 10 μm 2 up to 8 × 8 mm 2 . Interoperability between MINERVA and XPBF 2.0 will be preserved in order to reinforce and boost the production and characterization of the mirror modules. MINERVA is funded by the European Space Agency (ESA) and the Spanish Ministry of Science and Innovation. Still in the detailed design phase, MINERVA will take 2 years to be completed for operation in 2022.

Thin silicon photodiodes are common X-ray beam diagnosis devices at synchrotron facilities. Here we present a new device featuring an extremely thin layer that allows X-ray transmission over 90% for energies above 10 keV. The diode has a radiation-hard silicon junction with silicon dioxide passivation and a protective entrance window. These outstanding features make this device suited for diagnostic applications in X-ray synchrotron beamlines. Hereby preliminary results of X-ray transmission, responsivity and uniformity are presented.