The (100) surface of group IV semiconductors serve as a starting point for the vast majority of microelectronic technologies. We are particularly interested in silicon and germanium surfaces. The (100) surfaces of germanium and silicon contain atoms that are paired together in dimers that lead to a (2x1) reconstruction as pictured below.
Each dimer bond can be thought of as containing a strong σ-bond and a weak π-bond.
Thus the ideal reconstructed surface contains rows of dimers (or
rows of π-bonds). This research is
directed at activating these dimer rows for reaction with organic
substrates. The order of the dimer bonds on the semiconductor
surface then plays a major role in determining the order of the
organic film.
Our approach is to use cycloaddition chemistry between an unsaturated organic compound and the germanium surface dimers present on the (100) surface. The adsorption and reaction of a number of cyclic unsaturated hydrocarbons with the Ge(100) surface have been investigated. Well defined ordered organic layers are formed on the Ge(100) surfaces. Below is a schematic drawing of cyclopentene molecules attached to a germanium surface after reaction. To the right side of the drawing is an STM image of the surface showing ordering of the organic film along the dimer rows.
In these studies, data are obtained for a number of different
starting precursor molecules using photoelectron spectroscopy,
high resolution electron energy loss spectroscopy, scanning
tunneling microscopy, and temperature programmed desorption. The
molecules investigated include 1,3-cyclohexadiene,
1,4-cyclohexadiene, 1,5-cyclooctadiene, cyclopentene, and
cyclohexene.