Streamlined Inexpensive Integration of a Growth Facility and Scanning Tunneling Microscope for in situ Characterization

The limitations of silicon-based technology have become increasingly evident, leading research efforts to focus on more promising materials, such as graphene. In contrast to silicon, graphene’s most important properties reside on its surface, rather than on the characteristics of its bulk. Surface techniques, such as scanning tunneling microscopy STM , are therefore required to manufacture and study graphene. Graphene is manufactured using a variety of methods, such as mechanical exfoliation of graphite, thermal reduction of silicon carbide, and precipitation of carbon dissolved in transition metals. Most recently, the production method of choice has been epitaxial growth of graphene on a metal substrate such as nickel or copper using chemical vapor deposition CVD , as well as a related technique which involves the deposition of pure carbon in a vacuum environment on a heated copper substrate. While the former method is becoming increasingly popular for producing graphene for research purposes, much remains to be learned about the procedure. For example, metal substrates typically exhibit widely varied surface topography, and it is yet to be explained how this affects the nucleation and growth of graphene. Another area in need of clarification is the nucleation process and its role in determining the orientation of the graphene. Finally, more can be learned about the impact a step edge has on the graphene as it grows across the surface from a nucleation site, as well as what occurs when growths from two distinct nucleation sites meet. Examining the surface of samples with STM at various points throughout the growth process may yield insight to these questions. For such STM studies, several conditions must be met. First of all, in most cases, the substrate must be heated to 1000 °C to remove the surface oxide in preparation for growth. Second, the sample must be transferred in vacuum between facilities—a growth facility GF and an STM-to avoid contamination of its surface. Finally, the sample must be held rigidly to the STM stage to ensure vibration isolation. These conditions can be met by connecting the STM chamber to the GF so that samples may be transferred between the two in a controlled environment. Such a setup