Background

Deep ultraviolet LEDs are preferable for wide use as an alternative to mercury lamps since they are ultraviolet sources with low environmental impact. In recent years, their sterilization function has been especially attracting great attention, and practical application of this function is expected soon. In order to increase light emission efficiency and carrier lifetime, the quality of the AlN layer, which is the base for the active layer, must be improved. In this measurement example, an appropriate evaluation method was examined for the crystal orientation distribution (twist width) in the in-plane direction, which is used as an indicator of the threading edge dislocation density of the AlN layer.