Abstract
The silicon is popular using in our practical life, such as electronic devices, sensors, and solar cell, because it performs the well electronic characteristics with the low cost. The modern device size is smaller and smaller causing the surface/volume ration increases a lot. Therefore, the manipulation of Si surface properties attracted many attentions. We propose that the n-alkanethiols molecules serve as the chemical and physic passivation. In this thesis, we discuss the molecular structure, the growth mechanism, and the electronic structure. In addition, we develop two methods for a local functionalization to expect n-alkanethiol/Si for practical applications. We grew n-alkanethiols on bare Si (111) surface by UV-assisted photochemical reaction. First, we discussed the growth mechanism about role of UV irradiation in the photochemical reaction. By controlling the chain length of n-alkanethiols, the growth model is dependent with the intermolecular and molecule-substrate interaction. Further we also found the odd-even effect in the resulting monolayer. To utilize n-alkanethiols/Si in practical applications, we examined its thermal stability with the varied chain length. While the environmental temperature higher than thermally critical temperature, the molecules thermally desorbed from Si surface or embedded into Si substrate. On the other hand, the electronic properties of Si were modified by the implanted n-alkanethiols molecules. We demonstrated the space charge layer of different types and carrier concentration Si surface was changed. The grafted monolayer on p-type Si surface induced an inversion layer which is a potential modification as solar cell applications. In order to promote self-assembled monolayer for more practical application, the local functionalization is required to develop. We utilized two methods: focusing electron or X-ray irradiated to damage the monolayer structure and re-graft the second functionality monolayer. The other method is exposing N2 plasma reacted with the surface functionality to transform the functionality nitrogen related. The plasma radicals drained into the polymeric stamp for the local modification.