Research: Surface Modification
The semiconductor/liquid contact provides a natural testing ground for evaluating the properties of chemically modified semiconductor surfaces. The goal of chemical modification is to produce improved electrical, electrochemical, chemical, and physical properties to semiconductor surfaces relative to the behavior of the "natural", etched surfaces. These are often highly susceptible to corrosion or passivation, and also are highly defective electrically. As chips become smaller, the ratio of surface to volume will become higher, and surfaces will play an increasingly important role in determining the overall device properties. The goal of this portion of the work is to develop wet chemical means to modify the surfaces of technologically important semiconductors while obtaining improved chemical and physical properties from such systems.
Work on Si has focused on development of a two step, chlorination/alkylation process that leads to the production of defined organic overlayers on Si surfaces. These surface reactions have been shown to produce improved resistance to surface oxidation, while maintaining excellent electrochemical and electrical properties. In fact, the surface recombination velocity of the methylated Si surface has recently been determined to be less than 20 cm per second, which is comparable to high quality hydrogen-terminated Si surfaces but which is stable in contact with atmospheric ambients.
Work on InP has elucidated the surface chemistry of both the In-rich and P-rich faces of the (111) orientation of this important semiconductor. A series of functionalization reactions has been elucidated through which the chemistry of this surface can be manipulated while maintaining superior electrochemical and electrical properties. These reactions allow elaboration of the surface chemistry of InP without deleteriously affecting the electrical properties of the resulting interfaces.