A Study on Porous Silicon Gas Sensors: Metal Oxide Depositions to Organic Materials

Abstract

This paper has two main topics. The first topics covers the detection of volatile organic compounds with porous silicon (PSi) sensors. The second part explores the possibility of using conducting polymers as coatings for the PSi sensors as a catalyst for CO and CO2 detection. Porous semiconductor materials have been sought after as volatile organic compound gas sensors due to their optical properties. However, the optical sensors have a major flaw in their inability to distinguish different gases. Additionally, optical porous semiconductor sensors are overly sensitive to environmental factors, demising their ability to be used in an industrial setting. Therefore, in this project, we seek to explore methods using conductometric porous silicon sensors, potentially solving the drawbacks of optical sensors. Additionally, we seek to use the data collected during this period to construct a better understanding of the interaction of gases and porous semiconductor materials, expanding on the inverse hard/soft acid/base theory. Another flaw of porous semiconductor sensors is that they rely on the competing precesses of chemisorption and physisorption. If a gas is both physically and chemically inert, then the sensor will fail to detect the gas. However, certain polymers have the capability of acting as a catalyst, triggering electron exchange between the gas and sensor, producing the signal needed for detection. Studies have shown polypyrrole as a effective catalyst for CO2 detection. We wish to combine that with metal oxide deposits for studying CO2 in the IHSAB model.