Functionalization of Semiconductor Surfaces

CHAPTER 9

Ab Initio Molecular Dynamics Studies of Conjugated Dienes on Semiconductor Surfaces

MARK E. TUCKERMAN AND YANLI ZHANG

9.1 INTRODUCTION

The chemistry of hybrid structures composed of organic molecules and semiconductor surfaces is opening up exciting new areas of development in molecular electronics, nanoscale sensing devices, and surface lithography [1,2]. Covalent attachment of organic molecules to a semiconducting surface can yield active devices, such as molecular switches and sensors or passivating insulating layers. Moreover, it is intriguing to consider how the reactions might be controlled by “engineering” specific modifications to organic molecules and/or surfaces, suggesting possible new lithographic techniques.

One of the goals of controlling the surface chemistry is the creation of ordered nanostructures on semiconducting surfaces. Indeed, there has been some success in obtaining locally ordered structures on the hydrogen-terminated Si(100) surface [3–7]. These methods require a dangling Si bond without a hydrogen to initialize the self-replicating reaction. Another popular approach eliminates the initialization step by exploiting the reactivity between surface dimers on certain reconstructed surfaces with the π bonds in many organic molecules. The challenge with this approach lies in designing the surface and/or the molecule so as to eliminate all but one desired reaction channel. Charge asymmetries, such as occur on the Si(100)-2×1 surface, lead to a violation ...