In Desorption in InGaN Nanowire Growth on Si Generates a Unique Light Emitter: From In-Rich InGaN to the Intermediate Core-Shell InGaN to Pure GaN

We study the desorption of In in InGaN nanowire (NW) growth on Si, generating a unique light emitter. With increasing growth temperature above the onset of In desorption, uniform, In-rich InGaN NWs evolve into the intermediate core-shell InGaN NW structures with In-rich core and In-poor shell before the In-rich core is dissolved and pure GaN NWs are left. The different InGaN NW structures are characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX) spectroscopy. A growth model is developed to understand the distinct growth regimes by the interplay of anisotropic In surface diffusion and In desorption on the m-plane NW sidewalls and the c-plane NW top. The self-formed core-shell InGaN NWs are identified as the active region of our InGaN red light-emitting diode.