Displacement Damage Effects in Germanium Tin LEDs
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Air Force Institute of Technology Wright-Patterson AFB United States
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The effects of radiation-induced deep-level defects on the electroluminescence intensity produced by Ge1-xSnx-based light emitting diodes LEDs are studied as a function of varying tin concentrations x 0, 0.02, 0.069, and 0.094. All of these devices tolerate relatively high levels of proton displacement damage, and devices with higher Sn concentration are up to10 times more tolerant of displacement damage than the Ge only x 0 devices. The energy level of the dominant deep-level defect is observed to maintain a roughly fixed spacing relative to the conduction band edge in each device. As Sn concentration increases and the bandgap decreases, this dominant defect energy level moves further from the mid-gap intrinsic Fermi level toward the valence band edge. This trend should equate to a beneficial reduction of trap-assisted recombination and generation rates in high Sn concentration devices. Notwithstanding this finding, theoretical considerations suggest the change in band structurefrom direct to indirect bandgap is likely most responsible for the increased displacement damage tolerance of the high Sn concentration devices.
- Electrical and Electronic Equipment
- Radioactivity, Radioactive Wastes and Fission Products