Effect of macroscopic stress on accelerated aging of GaInAsP channeled substrate buried heterostructure lasers

Abstract

We report the results of the measurement of radius of curvature of 1.3 and 1.5 μm wavelength GaInAsP-InP channeled substrate buried heterostructure lasers. The objective of this investigation is to quantify the macroscopic stress present in the device and correlate it with device reliability. The change in dc threshold current (ΔIth) after an accelerated aging test was used as a measure to access device reliability, with high ΔIth indicating decreased reliability. Changes were made in the p-side metallization to bring about a change in either ΔIth or radius of curvature and they included two different contact widths and different thicknesses of the Au bonding pad. It is observed that no correlation between device curvature and ΔIth exists even though the modifications in the p metallization caused significant changes in both quantities. It is suggested that it is not the macroscopic device stress that is measured by the radius of curvature but localized stresses that may exist in the vicinity of the lasing active layer which would affect device reliability. It is surmised that the most important role of stress is its effect on the direction of defect migration with the principal driving force coming from the nonradiative electron-hole recombination occurring in the vicinity of the active layer.