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Nuclear & Plasma Sciences Society

Distinguished Lectures

Dr. Allan Johnston

Jet Propulsion Laboratory


Radiation Effects in Optoelectronic Devices

This two-hour course begins with a discussion of the physics of optoelectronic devices, including heterostructures that are important in III-V semiconductors. A brief discussion of radiation environments is included, along with methods to evaluate the effects of different proton and electron energies on damage in optoelectronics. The next section discusses displacement damage effects in detectors, light-emitting diodes, and laser diodes, noting the extreme sensitivity of some types of light-emitting diodes that has caused failure of several fielded space systems. The course also discusses optocouplers, including single-event upset from protons and heavy ions that cause those devices to be extremely sensitive to spurious pulses in typical space environments. A brief discussion of radiation effects in optical fibers and optical communication systems is also included.

An Introduction to Space Radiation Effects in Electronics

This two-hour course provides basic information about the effects of space radiation on electronics and microelectronics. It begins with a discussion of radiation environments near the earth, as well as in deep space where solar flares and galactic particles are the dominant source of radiation. Basic interactions of light and heavy particles are treated, and applied to fundamental electronic structures. The following section discusses various effects caused by the interaction of a single energetic particle, including single-event upset, latchup and gate rupture. Several examples are included to show how modern devices are affected by these phenomena, as well as how they are influenced by device scaling. The last section discusses total dose and displacement damage (which are caused by the integrated effect of many different particles). The material includes a discussion of enhanced damage at low dose rate (ELDRs), as well as methods for testing and selecting components that can withstand the harsh space environment.


Allan Johnston is a Principal Engineer at the Jet Propulsion Laboratory, a federally funded research center that is managed by the California Institute of Technology for NASA. He has more than thirty years of experience in radiation effects, and has participated in the design of several space craft, including the Cassini mission to Saturn, and several Mars exploration programs at JPL. He has published more than 100 technical papers, and is a Fellow of the IEEE.

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