Reliability of planar waveguide photodiodes for optical subscriber systems

This paper investigates the degradation mode and reliability of planar waveguide photodiodes (WGPD's) for the optical hybrid module for subscriber systems. From electroluminescence topography observations and current-voltage characteristics, it is clarified that the degradation mode for early failure is caused by the concentration of electric field or a microplasma at the edge of p-n junction. The condition for screening the devices likely to fail early without a bias-temperature test is determined by investigating the degradation mode. From optical beam induced current images, it is clarified that wear-out degradation, which governs the lifetime of WGPD's, occurs at the p-n junction perimeter on a cleaved facet. Estimation of activation energy, extrapolated lifetime under a practical use condition, and failure rates for wear-out and random failure show that the WGPD has sufficient reliability for optical subscriber systems.