AlN/AlGaN short-period superlattice sacrificial layers in laser lift-off for vertical-type AlGaN-based deep ultraviolet light emitting diodes

Abstract

Large-area (∼1 cm2) laser lift-off (LLO) wafer separation of Al0.45Ga0.55N layers from AlN/sapphire templates has been demonstrated by using 200-period AlN/Al0.22Ga0.78N short-period superlattice (SPSL) sacrificial layers instead of conventional GaN photoabsorbing layers. The SPSL functions as the photoabsorbing and mechanically weakened layer in the LLO process. This SPSL-assisted LLO technique promises future progress of vertical-type deep ultraviolet light emitting diodes and freestanding AlN–AlGaN bulk substrates.