Capacitive humidity-sensitivity of carbonized silicon nanoporous pillar array

The synthesis and application of silicon carbide (SiC) electronic devices have been studied broadly. In this letter, we report that by a thermal treatment process, the surface of silicon nanoporous pillar array (Si-NPA) could be carbonized in a graphite vacuum furnace. The composition and the morphology of the carbonized Si-NPA (SiC/Si-NPA) were characterized by X-ray diffractometer and scanning electron microscope. The humidity-sensing properties of SiC/Si-NPA were measured at room temperature. The result shows that with the relative humidity (RH) being changed from 11 to 95%, the capacitance of the sensor increased from 7.65 to 145.94 nF at the testing frequency of 20 Hz, and a capacitance increment over 1900% was achieved. The response and recovery times were determined to be similar to 10 s by carrying out vapor adsorption and desorption dynamic cycle experiment. The sensing performances are attributed to the unique surface structure, morphology and chemical characteristics of SiC/Si-NPA. (C) 2010 Elsevier B.V. All rights reserved.