| The reactions of dimethylzinc (DMZ) on the (4 x 2), (2 x 4), and c(4 x 4) reconstructions on GaAs(100) were studied using temperature programmed desorption (TPD) and high resolution electron energy less spectroscopy (HREELS). The results of the TPD experiments demonstrate that the strength on the Zn-surface interaction is a function of the surface As/Ga ratio. Zn atoms produced via dissociative adsorption of DMZ desorb at 565, 600, and 620 K from the (4 x 2), (2 x 4), and c(4 x 4) reconstructions, respectively. In contrast, methyl groups were found to desorb from all these reconstructions at 610 K. HREELS data for the (4 x 2) and c(4 x 4) reconstructions show that the energy of the surface-C stretching mode for adsorbed methyl groups is the same on these surfaces. These results indicate that the adsorption sites for methyl groups are similar on the three reconstructions. Based on these experimental results, models of the adsorption sites for Zn atoms and methyl groups on the (2 x 4) and c(4 x 4) reconstructions of GaAs(100) are proposed. |