The Reliability Of Planar InGaAs/InP PIN Photodiodes With Organic Coatings For Use In Low Cost Receivers

Low-cost optoelectronic components in non-hermetic packages are now required for use in the local loop, and these components will be subject to humidity-induced failure mechanisms. The results presented in this paper show that it is possible to provide some protection for the photodiode against the effects of humidity by means of an organic coating. Photodiodes with three different organic coatings were tested at 85C/85% relative humidity, and all survived longerthan uncoated control photodiodes. One of the coatings was superior to the other two, and photodiodes with this coating may have adequate reliability for some local loop applications. The temperature and humidity acceleration factors for uncoated photodiodes were determined. The temperature acceleration factor was found to be low (equivalent to an activation energy of 0.2eV, instead of the more usual 0.6eV). Failure analysis of failed photodiodes, which included Auger analysis of corrosion products, showed that failure was due to oxidation of the InP surface.