Synthesis and characterization of mixed methyl/allyl monolayers on Si(111).

The formation of mixed methyl/allyl monolayers has been accomplished through a two-step halogenation/alkylation reaction on Si(111) surfaces. The total coverage of alkylated Si, the surface recombination velocities, and the degree of surface oxidation as a function of time have been investigated using X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and microwave conductivity measurements. The total coverage of alkyl groups, the rate of oxidation, and the surface recombination velocities of Si(111) terminated by mixed monolayers were found to be close to those observed for CH(3)-Si(111) surfaces. Hence, the mixed-monolayer surfaces retained the beneficial properties of CH(3)-Si(111) surfaces while allowing for convenient secondary surface functionalization.