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Four pulsed-laser single-event effects systems, differing in wavelength and pulse width, were used to generate single event transients in a large-area silicon photodiode and an operational amplifier (LM124) to determine how transient amplitude and charge collection varied among the different systems. The optical wavelength and the focused spot size are the primary factors influencing the resultant charge density profile. In the large-area photodiode the transients can be distorted by high charge-injection densities that occur for tightly focused, higher energy optical pulses. When the incident laser-pulse energies are corrected for reflection losses and photon efficiency, with collection depth as a floating parameter (to account for diffusion), the photodiode data for all four devices lie on a single curve. The LM124 response varies with the specific transistor irradiated; similar transient shapes are measured for the different pulse wavelengths, with some deviations in the case of R1. These results reiterate that there is no single, optimum pulsed-laser system for SEE studies; that choice depends on the device to be tested, the intended application of that device, the goals of the test, and availability. For the specific devices evaluated here, any of the four laser systems would be sufficient for most tests.
Date of Publication: Aug. 2012