Single-event phenomena in GaAs devices and circuits

Final report on LDRD project 52722 : radiation hardened optoelectronic components for space-based applications.

“…The proton flux was set to about 1x10 6 protons/cm 2 -s. This flux was high enough to see frequent voltage pulses, but low enough to obtain accurate waveform counts with the oscilloscope and prevent permanent damage to the detector. To characterize the statistical nature of the voltage pulses, we adjusted the trigger level, counted the number of triggered pulses, and obtained statistics for the amplitude of the pulses.…”

“…The table gives the number of waveforms, or triggered voltage pulses, in a given period of time and flux. Using these values, we calculated a normalized count that gives the number of counts per second adjusted to a flux of 1.0x10 6 protons/cm 2 -s. Note that the normalized count increases with decreasing trigger level. It is reasonable to assume that trigger levels below 8 mV would have led to even higher counts.…”

“…The diameter of our detector is 74 µm (50 µm aperture with 12 µm wide metal ring contact) corresponding to an area of 4.3x10 -5 cm 2 . A flux of 1.0x10 6 protons/cm 2 -s leads to 43 protons passing through the detector every second. We measured 14.7 counts with an 8 mV trigger level, which is 34% of the total counts we would expect with better signal-tonoise.…”

“…The trigger levels were at 10 mV and 40 mV respectively. The flux was 1.2x10 6 protons/cm-s for 500 seconds for each measurement. The trigger levels were set higher due to increased noise resulting from VCSEL intensity fluctuations (largely optical feedback-induced noise when above threshold).…”

Charge Collection Mechanisms in AlGaN/GaN MOS High Electron Mobility Transistors

“…As such, single-event research in GaAs devices dates back to the early 1980s [30]. In the early charge collection work on GaAs, simple device structures were used, that were not necessarily any different from their silicon counterparts, as they included only p-n junction and Schottky-barrier diodes [31] (as opposed to later work, which investigated more complex heterostructure-based devices).…”