| Summary: | 碩士 === 國立高雄師範大學 === 物理學系 === 104 === The organic modification and functionalization of semiconductor surfaces is an important issue in the development of new semiconductor-based materials and devices by tuning the nature of the organic groups. In this study, the adsorption of 3,5-Dibromopyridine(35DBP) on the Ge(111) surface has been investigated by using scanning tunneling microscopy(STM) in an ultra-high vacuum(UHV) system. When 35DBP adsorbed on the Ge(111)-c(2×8) surface at room temperature, 35DBP self-assembled into a highly ordered pattern and the coverage-dependent STM morphologies were observed. There were classified into three kinds of the adsorption structure by the direction of line along the two bright protrusions (Br) of 35DBP with respect to the [ ] direction of the Ge(111) surface. According to the STM images, we proposed that 35DBP molecules favor to adsorb onto the electrophilic Ge adatoms with the Ge(111)-c(2x8) lattice by a N—Ge dative bonding, similar to pyridine on Ge(100). As annealing the substrate to 350K, 400K, 450K, 35DBP overlayer desorbed from the Ge surface resulting in the STM order domain decrease. Increasing the temperature to 500K, the bright protrusion images of dimers, trimers or larger cluster structures on the Ge surface were observed due to the cleavage of C−Br bonds.
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