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Single-event transients (SETs) from heavy ions and laser beam are investigated for two positive adjustable linear voltage regulators: the RH117 from Linear Technology and the HS-117RH from Intersil. Both positive and negative going transients are observed. The role of input voltage, load capacitance and supply current on the SET response is discussed. Index Terms--Laser, radiation testing, single-event transient, voltage regulator.

Radiation damage is investigated in optocouplers with power MOSFET output stages. They differ from conventional optocouplers, incorporating an intermediate photovoltaic chip to allow the MOSFET gate voltage to be controlled by the light-emitting diode. These optocouplers are sensitive to ionization as well as displacement damage, and can fail catastrophically from degradation in either the power MOSFET or the LED. Radiation testing must take both mechanisms into account. Index Terms--MOSFET, optocoupler, proton damage, space radiation effects.

Hardness assurance methods are examined for several types of optocouplers. A new diagnostic method using reverse-recovery time has a strong correlation with damage in the internal light emitting diode (LED). It depends only on electrical measurements, and can be used as a first-order parameter to determine LED properties when the LED technology of the optocoupler is unknown, as well as for evaluating unit and lot variability. For devices with internal LEDs that are highly sensitive to displacement damage, the dependence of phototransistor gain on operating conditions can impact post-radiation performance. For devices with radiation-tolerant LEDs, phototransistor characteristics and gain degradation are both important in determining the net effect of displacement damage. Index Terms--Hardness assurance, light-emitting diode (LED), optocoupler, space radiation.

We report catastrophic single-event latchup results for a CMOS operational amplifier. Thermal and optical imagings in conjunction with current distributions were used to identify latchup-sensitive regions. Differences in cross section for various ions show that charge is collected at depths beyond 40 [micro]m, causing the cross section to be underestimated unless long-range ions are used. Latchup testing with short-range ions may underestimate the cross section or even fail to trigger a latchup event that would occur with more energetic ions. Index Terms--Amplifier, cyclotron, heavy ion, latchup, LTC2052, SEE.

Degradation mechanisms are investigated for laser diodes fabricated with different materials and wavelengths between 660 and 1550 nm. A new approach is developed that evaluates laser degradation below the laser threshold to determine the radiation-induced recombination density. This allows mechanisms at high injection, such as Auger recombination, to be separated from low-injection damage. New results show that AlGaInP lasers in the visible region are nearly an order of magnitude more resistant to radiation damage than devices fabricated with AlGaAs or InGaAsP at longer wavelengths. Index Terms--Carrier removal, laser diode, proton radiation damage, space radiation.

Different silicon avalanche photodiode structures are compared for the effects of 51-MeV protons on dark current, photocurrent, and noise. Large differences in depletion region volumes contributed to differences in sensitivity to bulk dark current increases. At high fluences, ionization damage appeared to be the dominant mechanism for dark current increases in some devices. Increases in 1/f-type noise and supplemental gamma ray testing indicate that these high dark current increases are due to surface damage effects. A discussion of structural parameters that may heighten radiation sensitivity is presented, including doping levels and p-n junction termination techniques. Index Terms--Avalanche photodiodes, dark current, depletion region, ionization damage, noise, protons.

Evaluation of several types of CMOS devices after nondestructive latchup revealed structural changes in interconnects that appears to be due to localized ejection of part of the metallization due to melting. This is a potential reliability hazard for CMOS devices because it creates localized voids within interconnects that reduce the cross section by one to two orders of magnitude in the damaged region. These effects must be considered when testing devices for damage from latchup, as well as in establishing limits for current detection and shutdown as a means of latchup protection. Index Terms--Analog-digital conversion, CMOS integrated circuits, digital signal processors, electromigration, latent damage, oscillators, reliability, single-event latchup.

This paper presents a display of heavy-ion- and proton-induced single event transients for three comparators. The transient vital signs are serious: low LET threshold, very high voltage amplitude and extended pulse duration (microsecs.)