SBIR Phase I: Gallium Nitride High Temperature Gas Sensor for Measuring Combustion Gas Product Concentrations

该小型企业创新研究(SBIR)第一阶段项目包括设计、制造和测试连续和不连续催化金属薄膜，作为氮化镓金属半导体场效应晶体管(MESFET)气体传感器上的检测元件，用于测量高温气流中的燃烧气体产品。气体在金属表面吸附并发生反应。吸附物种的稳态组成改变了金属功函数。重大创新是氮化镓(大带隙)半导体器件，它将把这项新兴技术推向高温(约600摄氏度)应用。铂、钯/银、铑等多种催化金属具有不同的灵敏度和检出限。这些差异原则上可以用来区分最多三个浓度变量的影响。这将是这种传感器第一次使用铑。这项工作的结果将证明利用多催化门FET传感器技术可以量化高温气体成分的概念。一项工作成果将是：(1)气体(丙烷、甲烷、丙烯、NO、NO2和CO)在铂、PdAg和Rh多晶薄膜上的吸附等温线；(2)预期多种气体在这些金属上的显著相互作用的研究；(3)用X射线、电子显微镜和其他表面技术记录这些金属和氮化镓衬底之间的任何固态反应；以及，(4)在恒定气体和高达850℃的温度下对FET结构的机械和电气影响研究的目标是一种坚固的传感器结构和成分，可用于监测包括汽车尾气在内的燃烧气体，以实现催化转化器的“突破”，并可能用于发动机控制，以提高效率。这项研究的潜在商业应用是监测排放的传感器，以满足未来对超低排放汽车的预期法规要求。其他应用包括各种燃烧气体环境以及对炼油厂和其他工业化学过程的监控和实时控制。

This Small Business Innovation Research (SBIR) Phase I project comprises the design, fabrication and testing of continuous and discontinuous catalytic metal films as detection elements on a gallium nitride metal-semiconductor-field-effect transistor (MESFET) gas sensor for measuring combustion gas products in high temperature gas streams. Gas adsorbs and reacts on the metal surface. The steady state composition of adsorbed species changes the metal work function. The significant innovation is a gallium nitride (large bandgap) semiconductor device which will advance this emerging technology to high temperature (ca. 600 C) applications. The multiple catalytic metals: platinum, palladium/silver and rhodium have different sensitivities and detection limits. These differences can in principle be used to distinguish the effects of up to three concentration variables. This is the first time rhodium will have been used in this kind of sensor. The outcome of this work will be a proof of the concept that quantifying high temperature gas compositions ispossible with the multiple catalytic gate FET sensor technology. A work product will be: (1) the isotherms for gas (propane, methane, propylene, NO, NO2 and CO) adsorption on polycrystalline films of Pt, PdAg and Rh; (2) investigation of anticipated significant interactions of multiple gases on these metals; (3) the documentation of any solid-state reactions between the metals and the gallium nitride substrate by x-ray, TEM and other surface techniques; and, (4) the mechanical and electrical effects on the FET structure invarious gases and at temperatures as high as 850 C. The goal of the research is a robust sensor structure and composition that can be used to monitor combustion gas including automobile exhaust for "breakthrough" of the catalytic converter and possibly engine control for better efficiency.The potential commercial applications of the research is a sensor for monitoring emission to meet anticipated regulatory requirements for ultra-low-emissions-vehicles for the future. Other applications include a variety of combustion gas environments and monitoring and real-time control of refinery and other industrial chemical processes.