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Degradation behavior of avalanche photodiodes with a mesa structure observed using a digital OBIC monitor

The degradation behavior of avalanche photodiodes (APDs) with a mesa structure during bias-temperature aging is investigated. The dark-current variation using the optical-beam-induced current (OBIC) imaging technique is analyzed. A rise in the induced photocurrent was observed when the diodes were biased below the reach-through voltage indicating degradation, and the current path localized at the mesa edge of the absorption layer. The APD dark-current deterioration is well correlated with the OBIC observation, and the surface potential change near the mesa-edge surface is the most plausible cause of the deterioration. An APD with a lifetime exceeding 200 000 h at 85 degC, which is a sufficient reliability for receiver applications, has been achieved by preventing the degradation