Humidity Sensing And Electrical Properties Of Hmdso Plasma Thin Film

This paper reports the study of humidity-sensitive and electrical properties plasma polymerization of hexamethyldisiloxane (pp-HMDSO) thin film based sensors. The humidity sensitive film was deposited by glow discharge at low frequency power (19 KHz) in a capacitively coupled parallel plate plasma reactor. The sensor design comprises the intredigited electrodes and the absorbing layer. The sensor was calibrated in terms of impedance as a function of relative humidity, using a Frequency Response Analyzer. The signal frequency range was between 102 to 107 Hz with amplitude of 3V. Structural analysis of the sensitive layer was carried out by Fourier Transform Infrared spectroscopy (FTIR). Electrical properties, including capacity-humidity, hysteresis of the elaborated sensor were investigated. Interdigital electrodes and sensing layer were modeled using equivalent circuits to resolve the effects of adsorption and ion migration. The HMDSO films showed promising characteristics for humidity sensor development.