Surface science studies on electron-induced reactions of NH3 and their perspectives for enhancing nanofabrication processes

Abstract

Ammonia (NH₃) dissociates efficiently when it interacts with an electron beam. This applies not only to single electron-NH₃ collisions in the gas phase but also to electron irradiation of NH₃ adsorbed on surfaces. The dissociation products include atomic hydrogen which can act as a reducing agent or NH₂ radicals that can bind to suitable surfaces or to adsorbed molecules. This chemistry can be exploited in nanofabrication processes that use electron beams for deposition, etching, or modification of materials. This review describes the current state of insight regarding electron-induced reactions of NH₃ adsorbed on surfaces and outlines approaches to the use of these reactions for enhancing electron beam induced nanofabrication processes. First, an overview of surface science studies on electron-induced reactions of NH₃ adsorbed on single crystal surfaces is given. This is followed by a summary of studies on the use of NH₃ for improving the purity of deposits prepared by electron beam induced deposition (EBID) and on the prospects of NH₃ to suppress unwanted thermal surface chemistry during EBID. Finally, we discuss electron-induced reactions of NH₃ that are fundamental to the modification of carbonaceous nanomaterials as well as potential application scenarios such as the functionalization of self-assembled monolayers and humidity sensing.