水热腐蚀铁钝化多孔硅的湿敏特性研究

采用水热腐蚀铁钝化法在单晶硅片上生长铁钝化多孔硅(IPS)薄膜,以IPS为感湿介质制成湿敏元件。在不同湿度环境以及测试频率下,测出其电容值,得到了IPS的湿敏特性曲线。研究发现,当相对湿度从11%RH逐渐增加到95%RH的过程中,在测试频率为100Hz时,IPS湿敏元件的电容值增大幅度达1500%,电容响应时间在升湿过程和脱湿过程分别为15s和5s,并且IPS湿敏元件的温度系数在15℃到35℃的范围内较小。结果表明:IPS湿敏元件的特性包括灵敏度、响应时间以及温度系数等均优于多孔硅(PS)湿敏元件的特性。

Study on humidity sensing properties of hydrothermally etched iron-passivated porous silicon

Hydrothermally etched iron-passivated method is used to prepare iron-passivated porous silicon (IPS) on monocrystal silicon and a humidity sensor using IPS as a humidity sensing material is fabricated. Capacitance of IPS sensor is tested at different relative humidity (RH) under different signal frequencies and humidity characteristic curves are obtained. It is observed that the measured capacitance showed an increase over 1 500 % at a relative humidity (RH) ranged from 11 % to 95 % at the frequency of 100 Hz. The response time is reduced to about 15 seconds and 5 seconds respectively in a RH-increasing process and a RH-decreasing process. In addition, temperature coefficient of IPS humidity sensor between 15 ℃ and 35 ℃ is very small. As a result, humidity sensing properties of IPS sensor, including sensitivity, response time and temperature coefficient, are better than those of PS.