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

An understanding of the interaction of organic molecules with semiconductors is important for both fundamental research and technological applications. With such knowledge, it may be possible to bond a wide range of useful organic molecules directly to the semiconductor surface. The adsorption of ethylene, C2H4, on the arsenic-terminated GaAs(100) surface has been studied using high-resolution electron energy-loss spectroscopy (HREELS). We find that ethylene molecules are chemisorbed on the surface in a near-sp(3) hybridisation state at 300 K. Conversion from the physisorption state at 100 K to 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 electron-stimulated desorption (ESD) with low-energy electrons (0-50 eV) of the physisorbed species leads to quite different behaviour than heating; specifically, the desorption of H+ and CH3+ ions is due to C-H and C=C bond scission. respectively. (C) 1999 Elsevier Science B.V. All rights reserved.