pH sensitivity of nanocrystalline diamond films

Abstract

The pH-sensitive properties of hydrogen- and oxygen-terminated nanocrystalline diamond (NCD) films have been investigated using a field-effect-based capacitive electrolyte-diamond-insulator-semiconductor (EDIS) structure as transducer. The NCD thin films (100-500 nm) were grown on p-Si-SiO2 Substrates by microwave plasma-enhanced chemical vapour deposition. The electrochemical characterisation of EDIS sensors with NCD films of different thicknesses has been performed in buffer solutions of pH 3 to pH 11 by means of capacitance-voltage and constant-capacitance methods. The developed EDIS sensors with O-terminated NCD surfaces show an average pH-sensitivity of 38 mV/pH A slightly smaller pH-sensitivity of 29-36 mV/pH was observed for the EDIS structure with H-terminated NCD surfaces. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.