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

Abstract

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 (Ith), which is well correlated to a decrease in the sub-threshold emission; (ii) the Ith 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

P‐15.2: Light Output Degradation of Full‐frame Projection Laser Displays

“…accordingly, the ultimate lifetime of InGaAsP-InP lasers was concluded to be far longer than that of AlGaAs-GaAs lasers [2] . Degradation mechanisms and lifetime of state-of-the-art green laser diodes were analyzed and the factors affecting degradation rate were confirmed [3] . In general, the output power of laser diodes decreases mainly because of the increase of thermal stress generated during the laser operation at constant driving current.…”

Laser-Based Lighting: Experimental Analysis and Perspectives

“…For GaN-based LD, ageing induces an increase in the threshold current (Ith), whereas slope efficiency is generally not affected [ 11 , 12 ]; this mechanism is attributed to an increase in non-radiative recombination within the active region of the devices. Operating temperature also plays a role in the degradation, with a minor impact with respect to the driving current [ 13 , 14 ]. However, it should be noted that the reliability of GaN heterostructures has achieved satisfactory results in recent years, and the continuous development of GaN for GaN technology also ensures the stability of LD structures.…”

A generalized equivalent temperature model in a time-varying environment

“…In these models, power law degradation path model can describe both linear degradation path and nonlinear degradation path by different powers, and several empirical studies show that the expected degradation at time t is often proportional to a power law [2,17,19]. Moreover, this kind of model is widely used in engineering fields like electrical connectors, rubber materials [9], green laser diodes [11] and film resistances [1]. In addition, the power law degradation path has also been used to optimize the accelerated degradation experiment.…”

“…As a result, the degradation y 11 should be converted to the equivalent time τ 12 at temperature T 2 :…”