| Summary: | 碩士 === 國立中正大學 === 化學工程所 === 98 === This study explores the surface characteristics of octadecyltrichlorosilane (OTS) self-assembled monolayers (SAM) and their roles in depositing Ag-In-S semiconductor crystals on top of the modified glass substrates. First, the growth of OTS SAMs on substrates was studied. We reexamined the factors of growing OTS SAMs on glass and silicon substrates. These two substrates possess different-OH functional group contents and surface roughness. The composition, roughness, and surface morphology of OTS SAMs on these two substrates were investigated by changing solvents and reaction temperatures. It is known that the growth mechanism of OTS SAMs was controlled by the reaction temperature, and the resulting SAMs have different surface coverage and phase behaviors. A series of contact angle measurement, atomic force microscopy (AFM) and X-ray photoelectron spectrometer (XPS) were used to characterize the surface properties.
Finally, we deposited Ag-In-S semiconductor crystals on OTS-modified substrates. Crystalline AgIn5S8 crystals were grown on OTS-modified substrates without any post-thermal treatment. However, the morphology of AgIn5S8 crystals
was greatly affected by the precursor solution, as well as the surface properties of the substrates. The release of metal ions was adjusted by changing pH of precursor solution, in order to improve the distribution of AgIn5S8 crystals on the substrate and to prevent the crystals from aggregation. As a result, more individual crystals appeared, as seen from SEM images. The dimension of AgIn5S8 single crystal was observed to be about 1 μm. One parallel experiment was also carried out. The morphology of AgIn5S8 crystals changed with the concentration of complex agent, while the pH of precursor solution was kept at constant. In conclusion, individual AgIn5S8 single crystals can be evenly distributed on the substrates by tuning the pH of precursor solution. Also, SEM images showed that the coverage of AgIn5S8 crystals can be controlled qualitatively by the surface properties of substrates. The experimental parameters obtained in this thesis can be further used to deposit AgIn5S8 crystals on transparent conductive oxide as a absorb layer for solar cell applications.
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