Open AccessCapacitive humidity-sensing properties of Si-NPA and Fe3O4/Si-NPA
Author(s) -
Haiyan Wang,
Xinjian Li
Publication year - 2005
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.54.2220
Subject(s) - materials science , humidity , capacitive sensing , capacitive deionization , optoelectronics , computer science , electrochemistry , meteorology , electrode , physics , quantum mechanics , operating system
The preparation of silicon nanoporous pillar array (Si-NPA) and Fe3O 4 coated Si-NPA (Fe3O4/Si-NPA) is presented. The morphologies and microstructures of the two kinds of thin films were characterized and their corresponding capacit ive humidity sensing properties investigated. It was shown that both Si-NPA and Fe3O4/Si-NPA are typical micron/nanometer structural compo site systems. When the relative humidity increased from 11% to 95%, the capacitances reached 1500% and 5500% of their initial values measured with 100 Hz signal frequency, and 800% and 12000% measured with 1000 Hz signal frequency, for Si-NPA and Fe3O4/S i-NPA, respectively. At the same time, both of the two thin films exhibited quic k response speed, the response times in the humidity-increment and humidity-decr ement processes were determined to be 15 s and 5 s for Si-NPA, and 20 s and 15 s for Fe3O4/Si-NPA, respectively. These excellent humidity sensing properties of Si-NPA and Fe3O4/Si-NPA are explained based on thei r corresponding morph ological and structural properties. Our experiments strongly indicated that Si-N PA is an ideal thin film both for direct humidity sensing and as a substrate for growing composite humidity sensing materials.