Advances in SiC Field Effect Gas Sensors
Advances in SiC Field Effect Gas Sensors
复制标题
SiC 场效应气体传感器的进展
DOI：
10.1007/978-3-642-18870-1_36
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
S. Savage
中科院分区：
文献类型：
--
作者：
A. Spetz;S. Savage
围绕环境问题的制约日益严重。这就要求在车辆和工业中加强对排放的控制和减少能源消耗，这就需要开发和生产更快和更有效的在线控制传感器。可以在极端环境中工作的气体传感器有可能提供这种控制。那些基于宽带隙材料（如SiC， AlN, GaN， AlGaN和金刚石）的材料具有在腐蚀性大气和高温等极端环境中发挥作用的潜力。通过在器件表面使用催化材料，实现了基于多种场效应器件的化学气体传感器。在高温下工作的能力大大提高了对气体气氛变化的响应速度，为生产非常快速的传感器提供了潜力。在极端环境下（例如汽车尾气或烟道气体）直接在线测量的可能性，使得可以快速检测不需要的排放，从而可以立即调整系统，并允许满足低排放水平和燃料消耗的要求。碳化硅的宽带隙，4H-SiC为3.2 eV，允许工作温度高达1000◦C[1,2]，气体响应的时间常数为几毫秒[3,4]。基于碳化硅的电子器件可以通过在其表面的薄绝缘层[5]-[15]上沉积催化材料而起到化学传感器的作用。催化材料可以是例如铂、铱或钯等金属，或它们的组合。金属氧化物也可以用作不需要传导大电流的设备上的催化层。GaN、AlN和金刚石等其他宽带隙材料的带隙分别为3.4、6.3和5.5 eV。它们具有比SiC更高的带隙，因此具有在更高温度下工作的潜力。有几个小组已经开始开发基于这些材料的化学气体传感器，但这些材料的薄膜生长和工艺技术目前还没有像SiC那样成熟。因此，在技术成熟之前，这些设备的商业化是不可能的。
Constraints around environmental issues continue to increase in severity. This causes a demand for increasing control of emissions and reduction of energy consumption in vehicles and in industry, which necessitates the development and production of faster and more efficient sensors for on-line control. Gas sensors that can function in extreme environments have the potential to provide this control. Those based on wide band-gap materials such as SiC, AlN, GaN, AlGaN and diamond have the potential to function in these extreme environments such as corrosive atmospheres and at high temperatures. Through the employment of a catalytic material on the device surface, chemical gas sensors based on a variety of field effect devices have been realised. The capability for operation at elevated temperatures considerably increases the speed of response to a change of gas atmosphere, providing the potential for the production of very fast sensors. The possibility to measure directly on-line in extreme atmospheres, for example in car exhausts or flue gases, makes it possible to quickly detect unwanted emissions, which allows immediate adjustment of the system and permits the requirements of low emission levels and fuel consumption to be met.The wide band-gap of silicon carbide, 3.2 eV for 4H-SiC, permits an operation temperature up to 1000◦ C [1, 2], with time constants for the gas response of a few milliseconds [3, 4]. An electronic device based on silicon carbide can function as a chemical sensor by the deposition of a catalytic material on a thin insulating layer on its surface [5]–[15]. The catalytic material can be for example a metal such as platinum, iridium or palladium, or combinations of these. Metal oxides can also be used as catalytic layers on devices where the material does not need to conduct large currents. Other wide band-gap materials, such as GaN, AlN and diamond, with bandgaps of 3.4, 6.3 and 5.5 eV respectively, have also been explored. These have higher band-gaps than SiC, and so have the potential to function at even higher temperatures. Several groups have started to develop chemical gas sensors based on these materials, but the film growth and process technology of these materials is currently not so mature as for SiC. Therefore, commercialication of these devices cannot be expected until the technology has matured somewhat.