1-15 MeV proton and alpha particle radiation effects on GaAs quantum well light emitting diodes

Permanent radiation damage was investigated in gallium arsenide (GaAs) quantum well light emitting diodes (QW LEDs) due to protons and alpha particles in the 1-15 MeV energy range. At room temperature, these devices under forward bias emit infrared radiation at 980 mm, Current-voltage (I-V) and light emission characteristics of these devices were studied as a function of fluence and energy of protons and alpha radiations. For a given particle, the radiation damage in these devices increased with increase in fluence at a given energy, and decreased with increase in energy of the radiation at a fixed fluence, for both protons and alpha particles, Further, the alpha particles were observed to be far more damaging than the protons. These results agree qualitatively with the principal concepts of dependence of permanent displacement damage on nonionizing energy loss (NIEL) in the device. They are however found to deviate from the widely accepted concepts of damage dependence on fluence and particle energy. Based on the decrease in damage with increase in energy observed in QW LEDs in the present work and the results of earlier workers on energy dependence of damage in GaAs LEDs, it is concluded that these QW LEDs are more radiation hard than the modern GaAs LEDs reported recently. Further, there is less device to device variability of radiation damage between the QW LEDs than in the double heterojunction LEDs, 3 MeV proton radiation effects on device characteristics of quantum well infrared photodetectors (QWIPs) operating in the short wavelength infrared region are also reported.