Synchrotron-Radiation-Assisted Surface Processes of Diethylzinc on GaAs(100)

Abstract

The effect of sapphire-window-transmitted synchrotron radiation (longer than 150 nm photon illumination) and white-light synchrotron radiation (SR) on diethylzinc (DEZn), adsorbed on GaAs(100) at various temperatures, was investigated in situ using X-ray photoelectron spectroscopy (XPS). Illumination with light longer than 150 nm seems to have little impact on the adsorbed state whereas white light SR decomposes DEZn effectively, with the efficiency of dissociation for an adlayer of thickness around 3 nm to be roughly about 2.1×10-3 per shorter than 150 nm photons. The dissociation of DEZn seems to trigger the formation of clusters or islands of metallic zinc. At 115 K, we found that carbons and/or hydrocarbons desorb during white-light SR-assisted dissociation, and the desorption stops once dissociation is completed. In the process carbon decreases by approximately 40% at most regardless of the amount of excess photons available for the scission of all the Zn-C bonds. The surface becomes carbon-free once it is heated up to about 560 K. White-light SR irradiation of DEZn at 300 K, on the other hand, helps to desorb all carbon species, leaving a clean Zn coverage over the GaAs(100) surface.