SPACE RADIATION EFFECTS ON HIGH GAIN LOW CURRENT SILICON PLANAR TRANSISTORS.
Group rept. (Revised ed.),
LINCOLN LAB MASS INST OF TECH LEXINGTON
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The availability of silicon planar transistors with DC gains up to 300 at 10-microamps collector current has made it possible to design circuits with very low power consumption. By irradiating a number of commercial types with 1.5 Mev electrons in different circuit configurations, they were shown to be rather susceptible to space radiation. The most sensitive parameters are leakage current and low current gain. The effect on saturation voltages and on matching characteristics of transistor pairs was found to be minor, as long as the DC gain did not fall below 10. Under prolonged irradiation at electron fluxes representative of the inner Van Allen belt most transistor types had leakage currents considerably less than 100nA at emitter-collector biases not exceeding 10V. A few types exhibited leakage currents as high as 500 microamps A due to the formation of surface channels. A total doese of 10 to the 15th power esq cm reduced the DC gain in the 5- to 10-microamps A range of most to the transistors to values between 5 and 20. The gain after irradiation was governed by recombination-generation in the base-emitter region, but did not depend significantly on the pre-irradiation gain. Encapsulation of the transistor chip in a dense plastic material proved to be an effective method of preserving the gain under irradiation with a minimum penalty in weight and volume. Author
- Electrical and Electronic Equipment
- Radioactivity, Radioactive Wastes and Fission Products