Organic functionalization of semiconductor surfaces for selective assembly of nanostructures

Abstract

1. Monolayer Assembly and Striped Architecture of Co nanoparticle on Organic Functionalized Si(111) Surfaces: We present a new strategy to fabricate a monolayer assembly of Br-terminated Co nanoparticles on functionalized Si surfaces by using chemical covalent bonding and micro-contact printing method. Self-assembled monolayers (SAMs) of the Co nanoparticles formed on the hydroxyl-terminated Si surface exhibit two-dimensional island networks with locally ordered arrays via covalent linkage between nanoparticles and surface. On the other hand, SAMs of the nanoparticles on the aminopropyl-terminated Si surface show an individual and random distribution over an entire surface. Furthermore, we have fabricated striped architectures of Co nanoparticles using a combination of microcontact printing and covalent linkage. Microcontact printing of octadecyltrichlorosilane and selective covalent linkage between nanoparticles and functionalized Si surfaces lead to a hybrid nanostructure with selectively assembled nanoparticles stripes on the patterned functionalized Si surfaces. 2. Adsorption and Reaction of Methanol on Ge(100) Surface: The adsorption and reaction of methanol $(CH_3OH)$ on Ge(100) has been studied using ultrahigh vacuum scanning tunneling microscopy (UHV-STM) and density functional theory (DFT) calculation method. At low coverage, the high resolution STM image shows that methanol dissociatively adsorbs on the single Ge-Ge dimer. The adsorption feature consists of $Ge-OCH_3$ and Ge-H geometries by O-H dissociation of methanol. The real-time STM result reveals that the molecular chain of methanol is gradually grown by successive adsorption along the dimer row direction as increasing exposure of methanol. The saturation coverage (0.50 ML) is made up many bundles of these molecular chains. Also, high bias voltage STM experiment of Ge(100) adsorbed methanol leads to recombination of the adsorbed H and $OCH_3$ moieties and then molecular desorption. The ...