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 spectroscop y. We find that the ethylene molecules are predominantly adsorbed weak ly (physisorbed) on the surface with the C=C double bond parallel to t he As surface dimers. This behavior differs significantly from the ads orption of C2H4 on Si(100), as predicted by recent theoretical calcula tion. When the surface temperature is increased from 100 to 300 K, som e of the physisorbed C2H4 molecules convert to chemisorbed species. [S 0163-1829(98)02127-4].