Transferrable GaN-based Micro-LED heterostructures grown on h-BN for optogenetic applications

Individually transferrable GaN-based MQWs micro-LED structures grown on two-dimensional (2D) hexagonal boron nitride (h-BN) have been demonstrated. Different sizes (60 × 30 µm, 60 × 60 µm, 90 × 60 µm and 90 × 90 µm) of GaN-based LED heterostructures on layered h-BN were grown on dielectric SiN patterned sapphire substrates using Metal Organic Vapor Phase Epitaxy (MOVPE). Scanning electron microscope (SEM) images show micro-LEDs were grown with high selectivity within the mask opening areas. Consistent MQWs emission from micro-LEDs was observed at 452 ± 2 nm by cathodoluminescence (CL) spectroscopy for all micro-LED sizes. The structural and optical quality were similar to the GaN-based-LEDs grown on unpatterned substrates. In addition, we have successfully demonstrated the lift-off and transfer of individual micro-LEDs to arbitrary flexible templates using a transfer printing machine, which can be addressed by full front-end process. These studies highlight the role of combination of van der Waals (vdW) epitaxy and selective area growth (SAG) in facilitating the direct realization of dimensionally defined III-Nitride micro-LED structures and the mechanical release and transfer of these micro-LEDs to templates suitable for flexible display and optogenetics applications.