Interactions with ionizing radiation and conducting polymers

Ionizing radiation is found everywhere in space and comes principally in the form of electrons and protons. Any material to be used in space applications must exhibit hardness against ionizing radiation to prevent catastrophic mission failure. In this presentation, a general overview of the radiation environment found in low, mid- and geosynchronous-earth orbits will be discussed in the context of previous missions flown by the international space community which are publicly available. We will then discuss the performance of polymer-based infrared detectors with specific detectivities (D*) ranging between 10⁶-10⁹ Jones at room temperature. While some polymers such as classically doped polythiophene exhibit significant structural- and electrical changes at “low” total ionizing dose (TID) levels of 100 krad, other materials such as stable open-shell diradicals are radiation hard to over 1 Mrad TID. Infrared detectors fabricated from radiation hard conductive polymers are capable of operating in radiation environments >3x higher than commonly used III-V and II-VI semiconductor-based alternatives and are second only to CMOS technology; detectors based on the latter have a cut-off wavelength of 0.9 microns, compared to some polymer-based systems which operate up to 12 microns.