Facet-Engineered InGaN/GaN Nanorods Grown by Selective-Area MOCVD for Monolithic Multicolor Emission

We report the selective-area growth (SAG) of GaN nanorods and the subsequent formation of InGaN/GaN multiple-quantum-well (MQW) structures designed for monolithic multicolor micro-light emitting diodes (μ-LEDs). Site-controlled GaN nanorods were realized by metal–organic chemical vapor deposition (MOCVD) using nanoscale SiO2 apertures that enabled facet engineering through epitaxial lateral overgrowth (ELOG). Controlled nanoseed formation revealed that shorter growth times produced uniform cylindrical rods, whereas extended SiH4 exposure induced SiNx passivation and surface roughening. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses confirmed reduced surface oxides, improved Ga–N bonding, and preserved wurtzite (0002) orientation, indicating enhanced surface stability and crystalline uniformity of the templates. Based on these optimized conditions, pulsed MOCVD enabled the growth of InGaN/GaN MQWs on inclined facets with improved morphological uniformity and expected mitigation of the quantum-confined Stark effect (QCSE). The resulting “island-on-rod” LED structure exhibited wafer-scale multicolor emission ranging from 460 to 518 nm, governed by geometry-dependent indium incorporation. This work demonstrates a geometry-driven growth strategy that combines facet control and emission tunability, providing a scalable pathway toward high-efficiency, color-programmable GaN-based μ-LEDs for advanced display and photonic applications.