Nickel and lead phthalocyanine (NiPc and PbPc) thin films prepared by vacuum sublimation have been investigated for use as gas sensors. High sensitivity (25 ppb), reversibility, and very fast response time (∼ seconds) have been demonstrated for detection of NO2 at room temperature. The sensor output increases by five to seven orders of magnitude as the gas concentration is increased from ∼2×101 to 6×104 ppb. Measurements of transient response characteristics versus gas concentration exhibited a simple logarithmic dependence. Application of this approach to the detection of other agents is discussed. It appears that the unique electrical properties of these films are a result of the film morphology associated with our specific deposition approach. Detection based on optical sensing of NO2 has also been demonstrated.

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Thin films of nickel phthalocyanine and copper phthalocyanine were deposited on substrates heated to 160 °C. These films were characterized by transmission electron microscopy, electron diffraction, and thickness and density measurements. The films were 1000–1500 Å thick and contained α phase crystallites with the stacking axis parallel to the substrate surface. Implications for electrical properties of the films are discussed.

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Potential propagation over the surface of hermetically sealed or plastic coated semiconductor products may produce failure. A special test structure has been used to characterize the rate of propagation as a function of a number of parameters: humidity, temperature and selected organic coatings. A surface memory effect associated with exposures to humid ambients is discussed. This effect may explain in part the surprisingly wide range of surface instability observed in units hermetically sealed using state-of-the-art packaging techniques. Organic coatings, e.g. silicone varnish, reduce the influence of humidity at temperatures below 90°C. Arrhenius plots obtained in detailed studies at high temperatures allow estimation of stability performance in the 150'C to 200°C range as a function of material composition and curing time.