High-sensitivity phthalocyanine LB film gas sensor based on field effect transistors

A new kind of symmetrically substituted copper phthalocyanine derivative was synthesized. Metal-oxide-semiconductor field effect transistors (MOSFET) were designed for the measurements of FET characteristics. At the same time, oxide-semiconductor field effect transistors (OSFET) were specially designed with a long gate area for the measurements of gas sensitivity of phthalocyanine LB film. To obtain high sensitivity of the Langmuir-Blodgett (LB) gas sensor, FETs with depletion(D) p-channel mode were selected to be fabricated on the same monolithic silicon. LB multilayer films of copper phthalocyanine (CuPc) were later transferred to the long gate area of OSFET(D), forming the structure of LB-OSFET(D). The measurement of gas sensitivity for the LB-OSFET(D) sensor showed that higher sensitivity to NO2 could be obtained because of the effect of exhausted mode used in FET. This sensor can detect NO2 up to 0.1 ppm; it also exhibits good stability, excellent selectivity, and rapid response and recovery. (C) 1998 Published by Elsevier Science S.A. All rights reserved.