Tuning the Surface Potential and Work Function of Silicon Substrates with Self-Assembled Monolayers with Mixed Functional Groups
Date Issued
2010
Date
2010
Author(s)
Kuo, Che-Hung
Abstract
Bio-degradable polymers have been widely applied in the drug delivery, which has drug targeting specificity and selectivity. Most of these drug molecules are covalently bonded with the polymers and cannot be released easily. In this research, materials modified by self-assembled monolayers (SAMs) of multiple functional groups are prepared and studied. By depositing SAMs of different functional groups in different ratios, the properties of solid substrate, such as the isoelectric point (IEP) and work function, can be tuned. Through the difference in electrostatic interactions, molecules could be either adsorbed or desorbed with the surface of substrate by changing the environmental pH around the selected IEP. In comparison to the polymer-based system, the drug deliver platform using electrostatic interactions has more potential in development. In addition, the application of SAMs can also control the interface properties of opto-electronic devices and regulate the work function of materials that in turn affect the injection of charge carriers. The benefit of enhancing the device efficiency can be expected. As a commonly-used opto-electronic and high biocompatible material, silicon is used as the substrate in this work. The surface of silicon substrate is tailored with different ratios of H2N(CH2)3Si(OCH3)3 and HS(CH2)3Si(OCH3)3 in order to regulate its IEP and work function. The experimental results revealed that the IEP of silicon substrate can be adjusted from pH 2.24 to 7.94, and its work function can be fine-tuned between 4.02 and 4.99 eV.
Subjects
SAMs
mixed functional groups
surface potential
IEP
work function
Type
thesis
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