Ultrathin four-quadrant silicon photodiodes for beam position and monitor applications: Characterization and radiation effects

Abstract

Ultrathin semiconductor photodiodes are of interest for beam position and monitoring in X-ray synchrotron beamlines and particle therapy medical applications. In this work, single and four-quadrant diodes have been fabricated on ultrathin Si films with thicknesses of 10 μm, 5 μm and 3 μm from silicon on insulator (SOI) substrates. Physical and electrical characterization of the devices has been carried out. Good functional electrical characteristics have been obtained for the devices fabricated on the different silicon thicknesses. The impact of electron, neutron and proton irradiations on the electrical characteristics has been studied for the 10 μm-thick devices. In spite of the observed diode leakage current increase and positive charge trapping in interquadrant isolation oxide, functional operation as radiation detector is verified upon illumination with a pulsed laser beam transient current technique.