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Theoretical Study on Surface Electronic Structure and Adsorption of SnO2 Sensitive Film for Micro Gas Sensor

Author: WengXueJun
Tutor: JinRenCheng
School: Dalian University of Technology
Course: Mechanical Manufacturing and Automation
Keywords: Sensor First-principles Density of states SnO2 CASTEP
CLC: TH703
Type: Master's thesis
Year: 2006
Downloads: 345
Quote: 0
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Abstract


With the development of MEMS technology, the metal oxide gas sensor based on this technology has become a research focus. Such sensors have the advantages of low power consumption, easy integration, and is widely used in a variety of toxic and harmful gas, flammable gas, industrial emissions, environmental pollution gas detection. SnO 2 is a metal oxide gas sensing material is widely used, a lot of gas has a relatively good sensitivity, has a unique surface and interfacial characteristics at different temperatures in its crystal surface degree of oxygen deficiency (O vacancy), the film conductance test (sheet conductance measurement) show the presence of surface oxygen defects can increase the surface conductance nearly two orders of magnitude, from experimental and theoretical study of SnO 2 crystal surface defects and adsorption on the surface electronic structure of great significance to further improve sensor performance. In this paper, starting from the point of view of the improved sensor performance, SnO 2 (110) surface electronic structure and the gas molecules adsorbed. First use of the Materials Studio software SnO 2 (110) oxidized surface, partial oxidation of the surface, reducing surface and defects in the surface of the model, using first-principles density functional theory, combined with a plane wave pseudopotential and super cell method of calculation of the four surface geometry and electronic structure, focusing on analysis of the surface bridging oxygen hole and surface oxygen vacancies on the surface band structure, density of states, the atomic population and the impact of the charge density, and ultimately concluded the influence of surface defects film conductance and sensor performance. Also this paper Materials Studio software further study of oxygen in SnO 2 (110) restore the surface adsorption of oxygen molecules on the restore the surface of the five-coordinate tin atoms and the four-coordinate tin atoms above try Placement direction on the adsorption of the vertical, horizontal, etc., and eventually found the form of three stable adsorption, and then analyzes the oxygen in the SnO 2 (110) surface of the adsorption on the surface state density, the charge density and electronic structure of the impact of the factors that affect the micro gas sensor output and improved methods. Finally, on the basis of this study, given the improved micro gas sensor SnO 2 should be noted that the use of the sensitive film and sensor problems, and suggestions for further research tasks. This work laid the foundation for future research SnO 2 film adsorption and surface modification.

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CLC: > Industrial Technology > Machinery and Instrument Industry > Instruments, meters > General issues > Structure
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