Analysis of the Role of Current, Temperature, and Optical Power in the Degradation of InGaN-Based Laser Diodes

This paper reports on the degradation of InGaNbased laser diodes for Blu-ray technology. The devices have been submitted to stress under: 1) constant current, different temperatures; 2) high temperature, no bias; and 3) constant temperature, several current levels. The tests carried out within this paper demonstrate that stress determines the increase in the threshold current, according to the square root of stress time. The degradation rate has been found to be strongly determined by the stress current level, while the optical field had only a limited role in determining the degradation kinetics. The impact of temperature on device degradation is also limited, as confirmed by the activation energy value of 250 meV extrapolated by measurements carried out at different temperatures. On the basis of the evidence collected within this paper, we attribute the degradation of the lasers to an electrothermally activated process that induces an increase in the nonradiative recombination rate with subsequent decrease in the optical efficiency of the active layer.