Weak adsorption of ethylene on GaAs(100)

Hydrocarbon molecules are an important source of carbon contamination in semiconductor growth processes. We have investigated the adsorption of ethylene, C2H4, on the As-terminated GaAs(100)surface at 100 K in ultrahigh vacuum with high-resolution electron-energy-loss spectroscopy. We find that the ethylene molecules are predominantly adsorbed weakly (physisorbed) on the surface with the C=C double bond parallel to the As surface dimers. This behavior differs significantly from the adsorption of C2H4 on Si(100), as predicted by recent theoretical calculation. When the surface temperature is increased from 100 to 300 K, some of the physisorbed C2H4 molecules convert to chemisorbed species. [S0163-1829(98)02127-4].