2007 Volume 64 Issue 5 Pages 269-279
Two-dimensional molecular aggregation states of polyalkylsiloxane ultrathin films on silicon wafer substrates surface were investigated by various techniques. The in-plane grazing incidence X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and scanning force microscopy revealed that the alkyl chains in the octadecyltrimethoxysilane (OTMS) ultrathin films prepared by the CVA method (OTMS-CVA) are in an amorphous state at room temperature. On the other hand, octadecyltrichlorosilane (OTS) ultrathin films prepared by the solution chemisorption method and water-cast method are in a hexagonal crystalline state. According to lateral force microscopic measurements, the transition temperature from the hexagonal crystalline phase to the amorphous phase was found to be ca 333 K for the OTS ultrathin film prepared by the chemisorption method. However, the phase transition was not clearly observed in the OTMS-CVA ultrathin film. These results indicated that organosilane compounds in the ultrathin film prepared by the CVA method were immobilized on the silicon wafer substrate surface in an amorphous state, which was quite different from the hexagonal crystalline state obtained by the solution chemisorption and water-cast methods.
