Extending Feedback-Controlled Lithography to Ambient ConditionsPublic Deposited
Feedback-controlled lithography (FCL) enables atomically precise patterning of individual molecules on the technologically significant Si(100)-2 x 1:H surface. However, because it is performed in an ultrahigh vacuum (UHV) environment, FCL has thus far been restricted to surface chemistries that can be delivered in the gas phase. The present research attempts to introduce a new class of chemical and biological molecules — those suspended in liquid solvent — for use in FCL nanopatterning. Specifically, the Si(100)-2 x 1:H surface is removed from its native UHV environment and is subjected to liquid-phase chemical processing under atmospheric pressure conditions. A custom experimental setup, consisting of a UHV scanning tunneling microscope (STM) chamber that is directly interfaced to an inert atmosphere glovebox, facilitates liquid-phase chemical processing without exposing the pristine hydrogen monolayer to air-induced oxidation. While in the inert atmosphere, the Si(100)-2 x 1:H surface is treated with a variety of organic and aqueous solvents. Atomic resolution STM images reveal that the hydrogen passivation remains largely intact after treatments in toluene and dichloromethane. In addition, by minimizing oxygen levels during processing, perturbation to the Si(100)-2 x 1:H surface can be significantly reduced following exposure to water. This study delineates the conditions under which various organic and biological molecules can be delivered to nanopatterned Si(100)-2 x 1:H surfaces via liquid-phase solvents.