Development of MOS Capacitor Dissolved Oxygen Sensor for Use in High-Temperature Solutions

基于金属氧化物半导体(MOS)和电解质氧化物半导体(EOS)器件的新型溶解氧传感器已被开发出来，用于测量高温高压水溶液中的氧浓度。主要研究成果如下：1.设计并搭建了可用于测量MOS和EOS电容传感器高温响应特性的系统。PT-PtO_x电极对O2浓度变化的响应速度快，在高温下具有较高的耐腐蚀性。以单晶硅为半导体的多孔铂-MOS电容传感器在303-363K温度范围内，响应电压与对数[DO]浓度呈线性关系，但在423K以上出现裂纹。将体铂电极与二氧化钛单晶半导体电极相结合的铂-状态方程传感器表现出与铂-MOS传感器相同的DO响应特性，并且在423K.5以上仍具有良好的稳定性。得到了PtEOS传感器的DO浓度与响应电压之间的关系曲线。

New dissolved oxygen sensors based on metal-oxide-semiconductor (MOS) and electrolyte-oxide-semiconductor (EOS) devices have been developed for the measurement of oxygen concentration in high-temperature and high-pressure aqueous solutions. The results are summarized as follows ;1. The system that can be served for the measurement of response characteristics of MOS and EOS capacitor sensors at elevated temperatures was designed and constructed.2. Pt-PtO_x electrodes displayd a rapid response to changes in O_2 concentration and had a high resistance against corrosion at elevated temperatures.3. The porous Pt-MOS capacitor sensor fabricated using a single crystal silicon as a semiconductor showed a linear relationship between the response voltage and log [DO concentration] at temperatures of 303-363K.However, this sensor suffered from cracking at temperatures above 423K.4. The Pt-EOS sensor combining a bulk Pt electrode with a semiconductor electrode of TiO_2 single crystal displayd the same DO response characteristics as the Pt-MOS sensor, and had a good stability even at temperatures above 423K.5. Calibration curves, which provide the relationships between the DO concentration and the response voltage of the Pt-EOS sensor, were obtained.