Degradation mechanisms and lifetime of state-of-the-art green laser diodes

This paper presents a detailed analysis of the degradation kinetics and of the reliability of state-of-the-art InGaN-based green laser diodes (LDs), submitted to CW stress tests at different operating conditions. Results described in the following indicate that: (i) constant current stress induces an increase in threshold current (I<inf>th</inf>), which is well correlated to a decrease in the sub-threshold emission; (ii) the I<inf>th</inf> increase has a power law dependence on stress time; (iii) the degradation rate is strongly dependent on the stress current level while it does not significantly depend on the optical field in the cavity; (iv) stress temperature acts as an accelerating factor for LDs degradation; the activation energy of the degradation process is equal to 258 meV; (v) pure thermal storage does not induce a significant degradation of device characteristics. Cathodoluminescence measurements were carried out to get more insight into the physical origin of the degradation process.