Study of selective graphene growth on non-catalytic hetero-substrates

To incorporate graphene layers into a complementary metal oxide semiconductor (CMOS), various growth techniques are needed, such as direct and selective growth at a low temperature. The selective growth on a heterogeneous substrate is the key technology for the realistic synthesis of various structures, including graphene. In this study, we addressed the origin of selective growth of graphene on a semiconductor over the dielectric materials. Based on ab initio simulations, we found that the adsorption energy of CH₄ on SiO₂ is much higher than that on Si and Ge. The growth differences of graphene on Ge and SiO₂ were also experimentally confirmed. While a continuous graphene layer was formed on the Ge surface at the initial growth stage that became thicker at increasing growth times, an incubation time was required for the nucleation of graphene on SiO₂. The analysis of the interface between graphene and SiO₂ indicated that the initially incorporated carbons could not contribute to the graphene growth because they reduced SiO₂ by forming CO as a by-product. Finally, 3.0 nm-thick graphene layers were selectively grown on a SiO₂-patterned Ge/Si(0 0 1) substrate. The selective growth of graphene on patterned semiconductor substrates will help broaden CMOS applications. (letter)