5.5-MeV proton irradiation of a strained quantum-well laser diode and a multiple quantum-well broadband LED

The degradation under 5.5-MeV proton irradiation of two classes of quantum-well-based fiber-optic light sources was evaluated for satellite applications. The first was an InGaAs/GaAs strained-layer quantum-well (QW) laser, and the second was a broadband light-emitting diode (LED) based on dual asymmetric quantum wells in the InGaAs/GaAs/AlGaAs system. The QW LEDs were more tolerant of proton irradiation (-3 dB power at approximately 3*10/sup 13/ protons/cm/sup 2/) than the QW lasers (-3 dB power at approximately 3*10/sup 12/ protons/cm/sup 2/). The LEDs were operated far into gain saturation with a high-loss cavity structure, while the lasers were operated in a region where gain was more sensitive to current density. Therefore, atomic displacement-related recombination sites had a greater detrimental effect upon the lasers than the LEDs. The lasers held constant slope efficiency, and current thresholds increased linearly with proton fluence, while both LED power and slope efficiency decreased with proton fluence. The determined damage factors for both devices were found to fall within values predicted from a universal damage relation previously reported by G.P. Summers et al. (1988).<
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