Laser-transferrable GaN HEMTs based on high-quality AlN/GaN/AlN sacrificing templates

Laser lift-off (LLO) technology is an effective approach to fabricate transferrable GaN high-electron-mobility transistors (HEMTs) and address self-heating effects during device operation. However, conventional approaches struggle with precise control of LLO positions and structural integrity of devices, especially for those with AlN-based back barriers (BBs). Herein, we develop a laser-transferrable GaN HEMT with a μm-scale AlN BB, which is grown on a novel template including a GaN sacrificing layer (SL) and a metalorganic chemical vapor deposition-grown AlN nucleation layer (MO-AlN NL). The MO-AlN serves as the dislocation filtering layer to suppress dislocation propagation in the GaN SL, thereby creating an optimized nucleation template for the AlN BB. As such, the AlN-on-GaN epitaxy proceeds in a coherent 2D growth mode with largely reduced threading dislocations and preserved compressive strain. The devices fabricated on this AlN-BB/GaN-SL/AlN-NL tri-layer template can be integrally detached by a 266-nm UV laser, which only breaks the GaN SL and leaves an intact device active region. This work simultaneously resolves the critical challenges in μm-scale AlN-on-GaN epitaxy and laser transfer of GaN HEMTs with AlN-based BBs, offering a viable approach to laser-transferrable GaN power/RF devices with customized device structures toward improved device characteristics and thermal management.