This paper presents a growth mechanism and a comparative study of the InN nucleation layers grown on epitaxial graphene (EG) by metal organic vapor phase epitaxy (MOVPE) and radio-frequency molecular beam epitaxy (RF-MBE). Before growing InN nucleation layers, the EG surface was formed on 4° off 6H-SiC substrates (both Si- and C-faces) by thermal annealing in Ar ambient. The MOVPE grown InN nucleation layers show three-dimensional (3D) growth from the very beginning due to lack of nucleation centers and for the long migration length on the EG surface. The MOVPE InN on the EG formed on Si-face SiC is nucleated with the step edge, while it is nucleated randomly over the entire EG surface on C-face SiC. In contrast, the RF-MBE InN nucleation layers grown on EG formed on Si-face SiC show a two-dimensional growth mode up to 3 ML, and then a further increase of nucleation layer changes the growth mode to 3D mode. The formation of adsorption sites on the graphene surface by introduction of defects plays a significant role to enhance the nucleation center and grow high-quality layers. A model of the InN nucleation layer on EG is geometrically developed for both growth methods.

This paper reports the fabrication of InN layers on the epitaxial graphene (EG) using radio-frequency plasma-assisted molecular beam epitaxy (RF-MBE). Prior to the fabrication of InN, single crystalline EG with step and terrace structure was formed on 6H-SiC (0001) substrate in an Ar ambient by the Si sublimation method. Single crystalline epitaxial layers of InN with smooth surfaces are successfully fabricated on the EG using RF-MBE. InN layers with terrace and step structure are grown on the graphene surface up to 2MLs, and InN are grown in a layer by layer 2D growth mode. If the number of layers is increased above 3 MLs, the terrace and steps disappear, and the growth mode changes to 3D mode. The Raman spectroscopy analysis shows that the interfacial stress is reduced for the InN layer grown on the EG surface. The quality of the grown InN layer on the EG surface achieved at present is comparable to the InN film grown on sapphire. This work opens the possibility of growing high-quality InN layers on the EG surface in the near future.

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