Macroscopic Stress and Device Reliability of 1.3μm and 1.5μm Wavelength GaInAsP Channeled Substrate Buried Heterostructure Lasers

Abstract

ABSTRACTThe macroscopic stress of 1.3μm and 1.5μm wavelength GaInAsP-InP channeled substrate buried heterostructure lasers is related with device reliability. The radius of curvature, R, of the device is taken as a measure of its macroscopic stress and the change in dc threshold current, ΔIth, after an accelerated aging test is taken as a measure of device reliability, with high ΔIth, indicating decreased reliability. R or ΔIth was changed by altering the p-side contact width or the p-side Au bonding pad thickness. No correlation was found between R and ΔIth. For example, changing the p-contact width from 6 to 125μm resulted in a reduction of ΔIth by a factor of 2 – 10 among the wafers studied. However, the change in the active layer stress, as determined by R−1, was at most only 25%. Similarly, increasing the Au bonding pad thickness from 0.6 to 9.0μm increased the active layer stress by a factor of 2, but with little change in Alt. It is concluded that the macroscopic stress does not affect device reliability for the GaInAsP lasers.