Microphotoluminescence mapping of packaging-induced stress distribution in high-power AlGaAs laser diodes

Spatially resolved photoluminescence line scans were performed to determine the local stresses in AlGaAs laser diodes designed for high-power operation at 808 nm. In this approach, the sign and magnitude of the local stress are deduced from the spectral shift of the peak associated with band-to-band transitions in the n-type GaAs substrate. The sensitivity of the technique (minimal equivalent hydrostatic stress that can be detected) can reach 10 MPa or better. Correlations between solder-induced stress distribution in the devices and estimated lifetimes are demonstrated.