Electrochemically controlled modification of CVD diamond surfaces

The surface chemical properties of CVD diamond play a crucial role in many of the potential device applications using diamond, encompassing areas such as, cold cathodes and photocathodes, surface conductive FET's, electrochemistry, and genomics and proteomics. There is therefore great interest in developing routes for surface modification, and in understanding the influences, which such surface modifications produce. In the present work, an electrochemical procedure was developed to produce chemically stable negative electron affinity (NEA) surfaces. CVD diamond electrodes were electrochemically oxidised at anodic potentials to produce oxygen functionalities, which were subsequently subjected to ion exchange with aqueous Cs+ ions. Characterisation with XPS reveals the presence of a surface monolayer phase with the expected presence of Cs and O. The surface modified with Caesium displays negative electron affinity (NEA) and high field emission yields, and is much more stable than caesiated diamond surfaces produced by vacuum techniques. This new process represents an example of how simple electrochemical procedures can be used to achieve surface modification results, which are not so easily realised using other approaches. (C) 2003 Elsevier B.V. All rights reserved.