Chemistry of Nanostructured Porous Si

University Of California-San Diego, La Jolla CA

Investigators

Abstract

This award from the Solid State Chemistry program in the Division of Materials Research to University of California San Diego is to develop an understanding of the effect of surface chemistry on the stability of porous silicon (Si) photonic crystals. With this award Professor Michael Sailor will probe the effects of chemical modification of the porous Si surface on its air and water stability using reactions designed to attach functional species via Si-Carbon bonds. Two related attachment chemistries would also be studied: electrochemical reduction of alkyl halides; and hydrosilylation of terminal alkenes. These chemistries have been found to impart remarkable stability to the porous Si surface relative to Si-H or Si-O surfaces. The fundamental question to be answered is: what is the reason for this improved chemical stability? A systematic study on the effect of pore dimensions, chain length of the organic modifier, surface coverage, and nature of the substituents on stability in air and aqueous media will be performed. The project should lead to new understanding of the reactivity of nanocrystalline silicon surfaces for potential applications in number fields. In recent years there has been increased interest in developing low-power, miniature sensors that can be used to detect toxics, pollutants, or chemical and biological warfare agents in the environment. There is similar high interest in portable sensors that can be used to diagnose illness. One of the biggest challenges in this area is to place the sensitivity and specificity of a laboratory-scale instrument into a palm-top or smaller package. The goal of this research is to develop the chemistry of nanomaterials that can enable such applications, among others. Starting with crystalline silicon wafers, the same material used by the computer industry to build microchips, the project will build nanoscale structures that can act as sensors for chemical or biological compounds. The project should lead to a better understanding of the chemistry of silicon nanomaterials that will enable advances in the areas of medical diagnostics and therapeutics, remote sensors for pollution monitoring and homeland security applications, information display and optoelectronics. The primary product of this work will be to provide graduate and undergraduate students with a highly interdisciplinary education in materials chemistry and nanoscience. The students will be prepared for a variety of challenging research positions in the high-tech and biotech sectors of industry, government, and academia.