Investigations on the resistance of the metal-free phthalocyanine and palladium bilayer sensor structure influenced by hydrogen

• Published in: Sensors and actuators. B, Chemical Vol. 105; no. 2; pp. 340 - 345
• Main Authors: Jakubik, Wiesław P., Urbañczyk, Marian W., Bodzenta, Jerzy, Pietrzyk, Mieczysław A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 28.03.2005
• Subjects: Bilayer structure; Hydrogen detection; Metal-free phthalocyanine; Palladium; Resistance measurements; Resistance measurements; Hydrogen detection; Palladium; Metal-free phthalocyanine; Bilayer structure
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2004.06.022

Results concerning resistance measurements of two metal-free phthalocyanine (Pc) and palladium (Pd) bilayer sensor structures under the influence of medium hydrogen concentrations (0.5–4%) in nitrogen and air are presented. These two bilayer structures of different thicknesses of metal-free phthalocyanine (55 nm and 80 nm) and the same thickness of palladium (∼10 nm) have been realized in an electric system. For the interaction in nitrogen the bigger response has been observed in a sample with a thinner phthalocyanine layer. For interaction in air a change in the response character (increase–decrease of resistance) it is clearly visible in a sample with a thinner Pc film. Between 2% and 2.5% hydrogen concentration in air the structure of the palladium phase changes from α to β. The resistance of the α-Pd structure increases with the increasing hydrogen concentration whereas in the case of the β-Pd structure an opposite behavior is observed. Such a change is observed only concerning the interaction in air and for a thinner phthalocyanine (Pc) layer. In a structure with a thicker phthalocyanine film this phenomenon occurs at a higher hydrogen concentration.