Long-Term Reliability Tests for InGaAlP Visible Laser Diodes

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Abstract
Long-term reliability tests of over 10,000 hours have been carried out for 670-nm-wavelength InGaAlP visible laser diodes at elevated ambient temperatures beyond 50°C. Lifetime characteristics of inner stripe structure lasers were investigated from the viewpoints of structural parameter and aging conditions. At least two degradation modes were observed in the InGaAlP laser. One of them was related to facet oxidation and reduced by facet coating. The other degradation mode strongly depended on the operation current density. Mean times to failure of 24,900 hours for facet-coated thin-active-layer (0.06-µm) devices and 17,200 hours for as-cleaved-facet thick-active-layer (0.1-µm) devices were estimated at 50°C. The activation energy of the lifetime was over 1.7 eV in the temperature range between 50°C and 60°C.