Temperature-humidity-bias behavior and acceleration factors for nonhermetic uncooled InP-based lasers

Abstract

The stability of uncooled InP-based laser diodes in humid ambients was studied. Nonhermetic devices were aged at two different temperatures and humidities at a constant current and at one temperature and humidity at six different drive currents. For all nonhermetic devices failure occurred as a result of a large increase in the threshold current. The reverse leakage current for the failures did not increase when the threshold current increased, indicating that the change in threshold was a result of a change in reflectivity of one or both facets. The hermetic control group of devices aged under many of the same conditions showed a gradual increase in both the threshold current and slope efficiency. The median lifetimes as determined by assuming a device was a failure when the threshold current increased by 50% was strongly dependent upon humidity temperature and drive current. The lifetime data was fit to and equation of the form lifetime exp(-E/sub /spl alpha///kT) exp(-B/sub RH/[RH/sup 2/]). The values of E/sub /spl alpha// and B/sub RH/ were 0.52 eV and 4.9/spl times/10/sup -4//%/sup 2/, respectively. The current drive data was fit to and expression of the form lifetime a exp(I/sup /spl alpha//I/sub op/) where I/sub /spl alpha// as 0.09 h/mA. The lifetime dependence on current drive was modeled by assuming that the drive current caused a local temperature rise through thermal resistance. This local temperature rise then caused a decrease in the local humidity at the diode surface through an expression of the form %RH/sub diode//spl alpha/ exp (-5990[1/(T/sub r/+T/sub ambient/)-1/T/sub ambient/])where where T/sub r/ is the local temperature rise due to thermal impedance. Finally, we present our preliminary results on the reliability of nonhermetic SiO/sub x/ passivated lasers. These results indicate that such lasers can be made with sufficient reliability for use in telecommunications application.