Functionalization of Semiconductor Surfaces

CHAPTER 14

Perspective and Challenge

FRANKLIN (FENG) TAO AND STEVEN L. BERNASEK

In the past two decades, research in the area of functionalization of semiconductor surfaces has elucidated reaction mechanisms of organic molecules on semiconductor surfaces in many examples. These studies have also led to designed semiconductor surfaces tethered with functional organic materials and biospecies, and have demonstrated molecule-based semiconductor devices and biosensing techniques. However, there remain many open questions.

In order to grow multilayer, three-dimensional, organic architectures, or to immobilize biospecies on semiconductor surfaces, a functionalized surface with outward facing functional groups is necessary. A chemically homogeneous organic monolayer is crucial for significant signal response. To form such a surface with a single functional group facing outward, a bifunctional molecule is typically used. In fact, obtaining methods that exhibit a high selectivity for attachment of only one functionality of the bifunctional molecule to the semiconductor surface is crucial. A protection group to passivate one of the two functional groups can be used in the direct reaction with the semiconductor surfaces. This would be followed by activation of the protected group in the attachment of the second layer of organic molecules. This approach can enhance surface selectivity for some bifunctional molecules. However, the selection of a specific protection group is challenging, and ...