writer：Hui-Juan Chen, Qing-Zhong Xue (?), Ming Ma, Xiao-Yan Zhou
keywords：Heterojunction
source：期刊
specific source：Sensors and Actuators B 150 (2010) 487–489
Issue time：2010年

Amorphous carbon (a-C) films were deposited on n-silicon by direct current magnetron sputtering at room temperature (RT) and the corresponding microstructures were characterized. The RT capacitive humidity sensing properties of the a-C film/n-Si (C/Si) heterojunctions were studied by a standard twoprobe method. The result shows that the capacitance of the heterojunctions increases with decreasing frequency, because the adsorbed water molecules can become more polarized at lower frequencies. It was also shown that with the relative humidity (RH) changing from 11% to 95%, a capacitive response
of over 200% was achieved at 1 kHz, and the capacitive response is highly linear with RH for the given frequencies. The increase in capacitance of the C/Si junction with increasing relative humidity can be attributed to the increase in the amount of physisorbed water having a dipole moment. The study shows that the C/Si junctions have potential application as humidity gas sensors.