Recent advances in flexible GaN-based devices and chips

Abstract

. GaN-based optoelectronics have developed rapidly and emerged as key pillars in advanced optoelectronics. However, the inherent rigidity of conventional epitaxial substrates imposes fundamental limitations on mechanical flexibility, hindering their deployment in next-generation wearable and bio-integrated systems. This review provides a comprehensive overview of the emerging field of flexible GaN-based optoelectronics, spanning from epitaxial innovation to system-level integration. It begins by discussing the paradigm shift from conventional three-dimensional bonding to van der Waals epitaxy utilizing two-dimensional (2D) materials. These 2D platforms mitigate lattice-mismatch strain, facilitate mechanical exfoliation through weak interfacial interactions, enable substrate recycling, and support the fabrication of freestanding single-crystalline membranes. Subsequently, this review summarizes the device physics and flexible implementations of key functional units, including micro-light-emitting devices, high-sensitivity photodetectors, laser diodes, and emerging neuromorphic synaptic devices. Particular attention is devoted to the pivotal role of transfer and integration technologies (e.g., laser lift-off, transfer printing, and fluidic self-assembly) that bridge the gap between high-performance rigid epitaxy and wearable chips. By elucidating the relationships among material growth, device physics, and integration strategies, this review highlights opportunities for the development of high-performance, intelligent, and flexible GaN-based systems. Applications ranging from flexible displays and biomedical devices to brain – computer interfaces and neuromorphic systems demonstrate the broad potential of this technology and identify key challenges and opportunities for commercialization and clinical translation. Overall, flexible GaN-based devices and integrated systems represent a promising platform for next-generation wearable, bio-integrated, and intelligent electronic systems.