30 MeV electron beam irradiation effects on GaAs1-xPxLEDS.

Abstract

LEDs of the ternary alloy GaAs.7P.3 were irradiated with a 30 MeV electron beam. The effects this exposure had on peak wavelength, absolute and relative light output intensities, and current-forward bias characteristics were studied. A simple model of LED current controlling mechanisms is described and a mathematical approach for deriving a descriptive damage-constant is provided. Observed irradiation effects consisted of increased current and decreased light output intensity for a given forward bias voltage and indicate that the devices tested are an order of magnitude softer to electron radiation than results previously reported. Damage constants were calculated: group 9 (2.9 x 10ˉ¹⁴ cm²/e), group A5 (2.6 x 10ˉ¹⁴ cm²/e), and group 3 (1.4 x 10ˉ¹⁴ cm²/e). Shielded and un-shielded devices were compared to determine if the secondary electron production from Bremsstrahlung losses would reduce the total fluence required for degradation. The results of this experiment were inconclusive. A procedure was developed to determine the electron beam current density for use in dose estimations. Electron doses were a factor of three higher when compared to the previous method of calculation.