Degradation of telecom wavelength LEDs by high energy proton irradiation

Future space mission utilize more and more optical links for internal data transmission but also for long-range open-space communications between different satellites. While silicon based components are strongly degrading under high energy particle irradiation, wide bandgap semiconductors are generally found to be more radiation hard. Low bandgap semiconductors are, however also often employed in space for data transmission and for high efficient solar cells. InGaAsP LEDs emitting at 1550 nm have been irradiated with a 68 MeV proton beam with fluences up to 1e13 p+/cm^2. While the peak emission wavelength and the spectral width did not change with irradiation, a more than 2 orders of magnitude decrease of the emitted power has been found for maximum fluence. Besides the properties as light emitters, also the complete characterization of the electrical characteristics as receiver under illumination with 1550 nm light has been done. The changes of the extracted device parameters are discussed, which enabled, together with impedance spectroscopy data to give a detailed picture of the irradiation induced electronic defects.