Spectral Tuning of Shallow-Junction Surface-Emitting Light-Emitting Diodes (LEDs) Through γ-Ray Irradiation

Effects of nuclear radiation on GaAs emitting diodes have been studied in various investigations. These studies included both devices in which the IR radiation was emitted from the N-side and devices in which the IR radiation was emitted from the P-side. In the references cited the devices were heavily doped with various dopants and the junctions were located approximately 20 μm below the semiconductor surfaces. Measurements following γ-ray irradiation indicated in all cases small shifts (1-4 nm) in peak wavelength of emission towards shorter wavelengths, with the amount of shift depending on the specific impuritiesl. This led to a hypothesis that interaction of nuclear radiation-induced-defects with impurities plays a role in the spectral shift. Other effects of the irradiation were to decrease slightly minority carrier lifetime, to attenuate heavily the emission intensity of the diode emitters, and to increase slightly the forward I-V slope.