Ž . Materials Science and Engineering C 14 2001 17–23 www.elsevier.comrlocatermsec wx Characterization of copper ion sensing thiacalix 4 arene films evaporated on semiconductor substrates M. Ben Ali a,b , N. Jaffrezic-Renault a , C. Martelet a, ) , H. Ben Ouada b , J. Davenas c , M. Charbonnier d a IFoS UMR r CNRS 5621 Ecole Centrale de Lyon, BP 163, F69131 Ecully Cedex, France b ( ) Laboratoire de Physique des Interfaces Monastir 5000 Tunisia c Laboratoire d’Etudes de Materiaux polymeres et biomateriaux, UniÕeriste Claude Bernard-Lyon 1, 69622 Villeurbane Cedex, France ´ ´ d Laboratoire LSIS UniÕeriste Claude Bernard-Lyon 1, 69622 Villeurbane Cedex, France ´ Received 13 December 2000; received in revised form 11 February 2001; accepted 14 February 2001 Abstract wx Ž . Thermal evaporation under vacuum of thin thiacalix 4 arene on electrolyte-insulator-semiconductor EIS - and ion-sensitive-field-ef- Ž . fect-transistor ISFET -based structures allows to obtain sensitive and selective sensors for copper metal ions. The sensitivity of such Ž . devices, varying from a Nernstian response 30 mVrdecade to about 18 mVrdecade was strongly dependent upon the film thickness. wx Such a film thickness influence onto the sensors behaviour was correlated to the morphology and the composition of the thiacalix 4 arene Ž . Ž . layer investigated using atomic force microscopy AFM , X-ray photoelectron spectrometry XPS and diffraction of X-ray techniques. wx Furthermore, the complexation of copper ions by the thiacalix 4 ane layer, reported by electrochemical measurements, has been confirmed Ž . by Rutherford backscattering spectroscopy RBS . q 2001 Elsevier Science B.V. All rights reserved. wx Keywords: Thiacalix 4 arene; EIS; ISFET; Chemical microsensor; Surface analysis 1. Introduction The detection of ion activities by sensitive and re- versible sensors has become a field of great interest during w x the past years 1,2 ; most attention has been focused on the use of microdevices and their possibilities offered by Ž . silicon-based transducers EIS, FET structures . To render this devices ionosensitive, it is necessary to functionalize wx them with sensing membranes 3 ; the physico-chemical properties of the chemical sensor are based on selective recognition of the sensing ionophore and of the guest species. A variety of organic supramolecules and poly- meric compounds have been used as sensitive membranes w x w x for ion detection 4,5 , in particular, calix n arene, macro- cyclic molecules having a rigid natural cavity, which are able to recognise ions and organic molecules, according to ) Corresponding author. Tel.: q 33-4-7218-6248; fax: q 33-4-7833- 1577. Ž . E-mail address: Claude.Martelet@ec-lyon.fr C. Martelet . wx a keyrlook interaction mechanism 6 . Recently, ISFET sensors for heavy metal ions such as silver, lead and Ž . copper II have been fabricated with various sulphur func- wx wx tional group-derived calix 4 arene 7 . In this respect, the wx w x newly prepared thiacalix 4 arene 8,9 represent a quite promising class of selective ionophore for ion sensing. The wx Ž . thiacalix 4 arene TCA is composed of benzene rings linked via sulphide bridges; it can make host–guest com- wx plexation with a metal cation. The parent calix 4 arene has Ž 2q . a poor affinity towards transition metal ions M , whereas TCA is an excellent chelating agent for such w x metal cations 10 . The present work is based on functionalization of EIS wx and ISFET by thiacalix 4 arene using a thermal sublima- tion process under vacuum, which allows a good control of the film thickness. Different surface analyses techniques Ž . were investigated AFM, RBS, XPS and X-ray to charac- w x terise the TCA layers. The preliminary results 11 con- cerning the sensitivity of the TCA-based sensors towards Ž . Cu II ions were confirmed in this study and correlated with some structural aspects of the TCA layers. 0928-4931r01r$ - see front matter q 2001 Elsevier Science B.V. All rights reserved. Ž . PII: S0928-4931 01 00204-1