The use of silicon as a scaffold for surface reactions is common due to its reactivity, conductivity, and economic availability. Silane compounds have an established propensity to form self-assembled monolayers (SAMs) whose terminal functional groups govern surface properties of the substrate. In particular, amine-terminated SAMs are of interest because further chemical modifications can introduce desired chemical groups on the surface. In this poster, the structures of SAMs prepared on silicon wafer using four aminosilanes (3-aminopropyltriethoxysilane (APS), N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (EDA), trimethoxysilylpropyldiethylenetriamine (DETA), and m,p-(aminoethyl-aminomethyl)phenethyltrimethoxysilane (PEDA)) are investigated by Fourier transform infrared spectroscopy with attenuated total reflectance mode (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). Further coupling reactions involving carbodiimide condensation of carboxylic, sulfonic, and phosphoric acids with the aminated surface are explored and monitored. Optimization of these surface reactions on silicon wafer will facilitate the immobilization of biomolecules via either peptide linkage (e.g., proteins) or phosphoramidite linkage (e.g., oligomer nucleic acids) in a convenient two-step process with an ultimate application to biosensor development.