A silicon composite thermal and ionization X-ray detector

Abstract

We have made a combination calorimetric and ionization X-ray detector by attaching a silicon p-i-n diode to a monolithic silicon microcalorimeter. Applying a bias to the diode enhanced the thermal signal, and with a reverse bias of 25 V we achieved a detection threshold of 8 eV, based upon energy scaling of the standard deviation of the baseline noise. We were able to measure a charge signal in the absence of applied bias on the diode, demonstrating that the junction potential is sufficient to drift the ionized charges to the contacts. A fraction of the electron-hole pairs created became trapped, manifested by excess broadening in the measured thermal signal and by using the variation of the thermal signal magnitude with reverse bias to fit for the fraction of charge that is trapped. The ability to collect charge without an applied bias is necessary to produce high resolution combination thermal and ionization detectors.