Thermal Neutron Damage in Bipolar Transistors.
Abstract
An experimental test was made of the hypothesis that the source of thermal neutron damage in bipolar PNP transistors is the result of thermal neutron captures by the Boron-10 present in the emitter region of the transistors. Transistors were specifically made using three different ratios of Boron-10 to Boron-11 as the emitter dopant material, and in four different geometries. Forty-two of these specially made transistors were exposed to thermal neutron fluences as high as approximately 5 x 10 to the 15th neutrons per square centimeter. In each case the damage observed corresponded to the fraction of Boron-10 to total boron used as the emitter dopant material, thus confirming the hypothesized damage mechanism. The dependence of the collector current, thermal neutron fluence, and emitter-base geometry on the observed gain degradation also indicated that bulk damage is responsible for thermal neutron damage in PNP transistors. Some devices were also irradiated in a fast-neutron environment. Fast neutrons were found to be approximately 100 times more effective than thermal neutrons in producing damage in the devices that use a naturally occurring ratio of Boron-10 to Boron-11 in the emitter.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1977
- Accession Number
- ADA049626
Entities
People
- T. D. Stanley
Organizations
- Air Force Research Laboratory