Heilmann, M.; Mazid Munshi, A.; Sarau, G.; Göbel, M.; Tessarek, C.; Fauske, V.T.; van Helvoort, A.T.J.; Yang, J.; Latzel, M.; Hoffmann, B.; Conibeer, G.; Weman, H.; Christiansen, S.: Vertically Oriented Growth of GaN Nanorods on Si Using Graphene as an Atomically Thin Buffer Layer. Nano Letters 16 (2016), p. 3524-3532
10.1021/acs.nanolett.6b00484
Abstract:
The monolithic integration of wurtzite GaN on Si via metal−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−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 concepts.