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

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_α/kT) exp(-B_RH [RH²]). The values of E_α and B_RH were 0.52 eV and 4.9×10^-4/%², respectively. The current drive data was fit to and expression of the form lifetime a exp(I^αI_op) where I_α 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_diodeα exp (-5990[1/(T_r+T_ambient)-1/T_ambient ])where where T_r is the local temperature rise due to thermal impedance. Finally, we present our preliminary results on the reliability of nonhermetic SiO_x passivated lasers. These results indicate that such lasers can be made with sufficient reliability for use in telecommunications application