Vertically Oriented Growth of GaN Nanorods on Si Using Graphene as an Atomically Thin Buffer Layer

The monolithic integration of wurtzite GaN on Si via metal amp; 8722;organic vapor phase epitaxy is strongly hampered by lattice and thermal mismatch as well as meltback etching. This study presents single layer graphene as an atomically thin buffer layer for c axis oriented growth of vertically aligned GaN nanorods mediated by nanometer sized AlGaN nucleation islands. Nanostructures of similar morphology are demonstrated on graphene covered Si 111 as well as Si 100 . High crystal and optical quality of the nanorods are evidenced through scanning transmission electron microscopy, micro Raman, and cathodoluminescence measurements supported by finite difference time domain simulations. Current amp; 8722;voltage characteristics revealed high vertical conduction of the as grown GaN nanorods through the Si substrates. These findings are substantial to advance the integration of GaN based devices on any substrates of choice that sustains the GaN growth temperatures, thereby permitting novel designs of GaN based heterojunction device concept