Laser lift-off of ultraviolet-C light-emitting-diode epitaxial layers with an AlGaN nucleation layer grown on a sapphire substrate

Substrate delamination due to laser lift-off (LLO) at sapphire/Al-rich AlGaN epitaxial layer interfaces in AlGaN-based light-emitting diodes (LEDs) is under-explored. We demonstrated substrate delamination in AlGaN-based ultraviolet-C LEDs grown on sapphire substrates using the LLO method and evaluated the delaminated interface structure. When the AlGaN epitaxial layer was irradiated by a 196 nm excimer laser from the back side of the sapphire substrate, a damaged area formed only on the sapphire side at the peeling interface, and not on the laser-light-absorbing epitaxial layer. These results will accelerate the development of LLO technology for growing AlGaN-based epitaxial layers on sapphire substrates.