Highly Reliable Operation of InGaAlAs Waveguide Photodiodes for Optical Access Network Systems

Abstract

Reliability of InGaAlAs mesa waveguide photodiodes suitable for low-cost modules applied to access network systems is investigated. Stable operation for 9600 hours has been confirmed so far in the bias-temperature accelerated aging test. Median lifetime at a field service temperature of 85°C is estimated to be over 100 years by using the measured activation energy of 0.48 eV. Change in dark current during aging is explained by the hole accumulation at the interface between a crystal surface and a passivation film. The waveguide photodiode is confirmed to be highly reliable for access network applications.

Reliability of InGaAs waveguide photodiodes for 40-Gb/s optical receivers

“…After the reliability testing of the WGPD test structures, the failure analysis on the thermally and electrically stressed WGPD test structures was carried out using the scanning electron microscopy (SEM) and the energy dispersive spectrometry (EDS). The degradation mechanisms for mesa-structure photodiodes have been reported by several researchers [3]- [5]. It was reported that one of the main reasons for the increase in dark current, which causes the failure of the devices, is the leakage path at the exposed surface of the p-n junction between the semiconductor and the passivated dielectric film.…”

“…It was reported that one of the main reasons for the increase in dark current, which causes the failure of the devices, is the leakage path at the exposed surface of the p-n junction between the semiconductor and the passivated dielectric film. It was proposed that the leakage path is formed by hole accumulation near lateral junction or accumulation of mobile ions in passivation film due to electric field [3]. Prior to the analysis, the presence of contaminants in passivating nitride and polyimide at the exposed junction was assumed as a possible cause for the dark current increase during the testing.…”

“…The WGPDs can surpass the bandwidth limitation beyond 40-Gb/s modulation because the quantum efficiency of WGPDs is just dependent on the length of the waveguide structure. In addition, the mesa-type, side-illuminated InGaAs WGPDs are advantageous for surface-hybrid integration because they can be easily flip-chip mounted on the planar lightwave circuit (PLC) and be directly coupled to Manuscript planar waveguides without requiring optical components such as lenses or mirrors [3]. Despite these merits, the reliability of the mesa structure must be carefully evaluated for the dark current instability from the exposed junction at the edge region [4].…”

“…Shishikura et al studied the reliability of WGPDs in a highly humid ambient [5]. Nakamura et al proposed degradation model on InGaAlAs waveguide photodiodes due to the trapped hole accumulation at the surface states [3]. Mawatari et al investigated the early failure mode and wear-out degradation mode for the reliability of the planar WGPDs [6].…”