The influence of surface structure on the reaction of dimethylzinc on GaAs(100)

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