The effect of roughness on the T3-dewetting of molecular hydrogen

Abstract

Triple-point dewetting is a well-known behaviour of molecular hydrogen and other van der Waals systems like noble gases on a solid substrate. Recent theoretical and experimental investigations (Phys. Rev. Lett. 88 (2002) 55702) suggest that it is caused primarily by the roughness of the substrate. Strain induced due to the mismatch of the lattice constant of the substrate and the growing layers of the adsorbed materials is increased by the micro-roughness of the substrate which eventually leads to the growth of only a thin solid film of the adsorbate. The dominating role of the substrate roughness is demonstrated, e.g., by ellipsometric measurements on smooth Si surfaces (rms 0.15 nm ), where a thicker solid hydrogen film than the 3 monolayers on “usual” substrates is observed. We present a way to modify and improve the surface quality of substrates for such wetting studies of solid van der Waals films.