Study on Degradation of Deep‐Ultraviolet Laser Diode

Abstract

The degradation of an AlGaN‐based deep‐ultraviolet laser diode during operation is studied. A rapid increase in threshold current without any facet mirror damage under direct current stress below the threshold current is observed, which is considered to limit the lifetime of continuous wave lasing to the level of seconds. The evolution of current–light and current–voltage characteristics suggests that the dominant mechanism of degradation is the increased loss of carriers before they can reach the active layer, i.e., the decrease in carrier injection efficiency. The decrease in emission intensity, which is more pronounced at lower current densities, and subsequent increase in sub‐threshold current indicate the increase in defect density under current stress, which is similar to the well‐analyzed degradation mechanism found in AlGaN‐based light‐emitting diodes.