Exploring driving forces for length growth in graphene nanoribbons during chemical vapor deposition of hydrocarbons on Ge(0 0 1) via kinetic Monte Carlo simulations

• DOI: 10.1016/j.apsusc.2020.146784
• Publication Date: 2020-06-04T23:25:48Z
• Authors: Florian Göltl; Ellen A. Murray; Benjamin W.J. Chen; Robert M. Jacobbe...; Michael S. Arnold; Manos Mavrikakis
• Keywords: 02 engineering and technology; 0210 nano-technology

Abstract Graphene grown slowly on Ge(0 0 1) using chemical vapor deposition of hydrocarbons leads to high-aspect ratio graphene nanoribbons with smooth edges and a technologically relevant band gap at room temperature; however, the driving forces leading to one-dimensional growth of such graphene crystals are not well understood. Here, we combine a lattice kinetic Monte Carlo approach based on steps in graphene growth and experimental measurements to study the growth of graphene nanoribbons via chemical vapor deposition on Ge(0 0 1). To identify potential reasons for growth of graphene as anisotropic ribbons, we study the impact of anisotropy in various growth parameters on the resulting graphene crystals. Comparing our model with experimental measurements indicates that anisotropy in the stabilization of a graphene precursor species bound to the graphene edge is the most likely reason why high aspect ratio graphene ribbons with smooth edges grow on Ge(0 0 1). Using the growth model developed here, we reproduce experimental trends in the synthesis of graphene nanoribbons on Ge(001) and arrive at an intuitive picture for their growth. These insights shed light on the driving forces governing this highly anisotropic regime of crystal growth.