Seminars Archive

Optimizing the CVD graphene growth for the construction of electron transparent membranes.

Abstract
An alternative approach towards Ambient-Pressure Photoelectron Spectroscopy (APPES) and microscopy can be realized by using gas tight, but electron transparent membranes. Such membranes may be used to seal a non vacuum compatible compartment and introduce it into the ultra high vacuum environment of an electron spectrometer. It is possible to investigate the interior of the sealed compartment by applying photoelectron spectroscopy, if the ejected photoelectrons can pass the electron window and enter into the electron analyzer. Due to the short inelastic mean free path of electrons in condensed matter, an extremely thin and mechanically stable membrane material is required for this application, especially if electron transparency for low energy electrons is needed. Therefore, we chose monolayer graphene as membrane material and thoroughly investigated its catalytic growth on polycrystalline Cu foils. We optimized the foil pretreatment and growth conditions in order to enable the growth of single crystalline g-flakes with diameters approaching the mm-range. Recent understanding regarding the involved processes during nucleation and growth of high quality graphene is reported and membrane fabrication concepts are discussed, including our current state of the art and the difficulties to be overcome.