Degradation of III-V Compound LED´S with Plastic Lenses

Degradation modes and mechanisms of III-V compound LED´S with epoxy lenses have been investigated. Degradation of epoxy lenses was first examined under various conditions. Degradation of light transmission characteristics, which plays an important role in the degradation of LED´S, was expressed as functions of temperature, wavelength and time. Degradation of diodes was next examined. Degradation of light output under forward biased conditions was expressed as functions of current density, ambient temperature and time for both unpassivated and passivated LED´S. The activation energy of degradation of light output was ca. 0.4 eV for unpassivated LED´S and was ca. 0.8 eV for passivated LED´S, respectively. Influence of water vapor upon light output was also investigated.