Measuring transistor damage factors in a non-stable defect environment

Late-time and early-time damage metrics such as the Messenger-Spratt response and annealing factor are used to measure and compare displacement damage in bipolar transistors across a variety of neutron and ion radiation facilities. These metrics depend on the use of ASTM standard specified thermal anneals to achieve time-stabilized transistor gains for the metrics comparisons. We report on a correlated bi-stability observed both in the defect population and the device late-time gain. This bistability can be cycled between a post thermally annealed state and the original post -irradiation condition by forward biasing the transistor at room temperature. These observations require that additional constraints be placed on the operating state of the device after irradiation if the purpose of the time stabilized ASTM thermal anneal is to be preserved. (author)