Adsorption and decomposition of ethylene (C2H4) on GaAs(100)

An understanding of the interaction of organic molecules with semiconductor s is important for both fundamental research and technological applications . With such knowledge, it may be possible to bond a wide range of useful or ganic molecules directly to the semiconductor surface. The adsorption of et hylene, C2H4, on the arsenic-terminated GaAs(100) surface has been studied using high-resolution electron energy-loss spectroscopy (HREELS). We find t hat ethylene molecules are chemisorbed on the surface in a near-sp(3) hybri disation state at 300 K. Conversion from the physisorption state at 100 K t o the chemisorption state is observed when the sample temperature is raised to room temperature. The sticking coefficient for ethylene on the surface at 300 K is about two orders of magnitude lower than that at 100 K. The ele ctron-stimulated desorption (ESD) with low-energy electrons (0-50 eV) of th e physisorbed species leads to quite different behaviour than heating; spec ifically, the desorption of H+ and CH3+ ions is due to C-H and C=C bond sci ssion. respectively. (C) 1999 Elsevier Science B.V. All rights reserved.