Abstract
In present paper, the fabrication and humidity sensing properties of aluminum phthalocyanine chloride (AlPcCl) thin film based sensors have been presented. AlPcCl thin films with nominal thickness of 50-100 nm are deposited on glass substrates between pre-deposited 50 nm thick aluminum electrodes. The gap between the electrodes is 50 mu m. It is observed that the sensing mechanism is based on the variation of resistance with change in humidity. For change in relative humidity (RH) from 20% to 92%, the change in resistance is 22.2 x 10(2) and 13.3 x 10(2) times respectively for the sensors having 50 nm and 100 nm thick AlPcCl films, while the 1 h annealing of these samples at 100 degrees C results in increase in average sensitivity up to 30% and 40% respectively. The consequence of measuring frequency and absorption-desorption behavior of the humidity sensor are also discussed in detail. It is also observed that annealing results in minimization of hysteresis and reduction of recovery time (tau(rec)) up to 63% and 70% in sensors with 50 nm and 100 nm thick organic film respectively, while the response (tau(res)) time is 10 s for both the sensors. (C) 2012 Elsevier B.V. All rights reserved.