Abstract
In this thesis, we have studied the formation of 1-dodecanethiol (DDT) self-assembled monolayers (SAMs) grown on hydrogen-terminated Si(111) surfaces. The surface wettability, electronic properties, molecular orientation, and molecular oriented transition dipole moment of the DDT/Si(111) film were studied by water contact angle, high-resolution X-ray photoelectron spectroscopy (HRXPS), polarized near-edge X-ray absorption fine structure (NEXAFS), and attenuated total reflection fourier transform infrared(ATR-FTIR). The 101° water contact angle and HRXPS measurement indicate the DDT is almost fully covered on Si forming a high quality and densely peacked methyl-terminates surface. Furthermore, a combination of NEXAFS and ATR-FTIR measurements revealed a structure of ordered alkyl chains tilted 33.4° related to the surface normal and calculated film thickness of 15 Å. To investigate the durability of the monolayer, the fresh DDT/Si(111) samples were kept in atmospheric condition from one day up to a month. From Si 2p and S 2p spectra, a slight increase of the oxide component was observed after a week. Moreover, by immersing sample into potassium hydroxide solution, we concluded that the oxidation of DDT/Si(111) is starting from the defect sites and domain boundary of the SAMs.