Bidirectional Control of Silicon's Surface Potential by Means of Molecular Coverage

Here we report on a simple bidirectional strategy for increasing and decreasing the surface potential of Si, with good chemical stability. The strategy is based on a deliberate control of monolayer coverage of propenyl molecules having a steric diameter that is smaller or comparable to the distance between adjacent Si surface atoms. By modifying the coverage of the exposed functional groups, we show an ability to obtain both valley-shaped or hill-shaped modulation trends of the Si(111) surface potential.