Radiation Damage in Lithium Drifted p-i-n Junctions

A major effect of radiation damage of semiconductor junction detectors is the decrease of charge carrier lifetime. The thick depletion regions and low fields usually employed in p-i-n junctions makes them particularly sensitive to radiation damage. A study of the changes of electron trapping lengths in silicon p-i-n junctions as a function of radiation damage by Co60 gamma rays is presented. Significant changes of collection efficiency and collection time were observed at doses (~105R) which are considered negligible for damage in p-n junctions. The variations of reverse current and noise were small for these low doses. A method of fabrication and encapsulation of p-i-n junction radiation detectors is described which utilizes ion drifting from a localized source of lithium and a gold-silicon alloy seal.