XPS study of in situ one-step ammination of nanocrystalline diamond films
S. Torrengo1,2, A. Miotello1, G. Speranza2 , L. Minati2, M. Ferrari3, A. Chiasera3, M. Dipalo4, E. Kohn4 1 Physics Dep. University of Trento, Povo, 38100 Trento, Italy. 2 FBK-IRST Sommarive str. 18, Povo, 38100 Trento, Italy. 3 CNR-IFN, CSMFO Lab., Via alla Cascata, 56/C, Povo, 38100 Trento, Italy. 4 Institute of Electron Devices & Circuits, Ulm University Ulm, Germany.
The recent advancement in coupling the semiconductor technology with biological molecules has given the possibility to develop biosensors for specific purposes. The hydrogenated diamond surface is one of the best platforms to develop a biosensor since it possesses rather unique properties. Among the other, diamond is highly chemically inert and then highly biocompatible. Grafting of biomolecules is highly stable in air and in aqueous environments. Finally the hydrogenated diamond surface is conductive while oxidized diamond is resistive. All these properties are the required ingredient to fabricate a surface gate field effect transistor (SGFET) for an organic label free molecular recognition. The diamond surface conductivity is very sensitive to the molecular species on its surface. Diamond based SGFET may then be used to detect the DNA hybridization. On the other hand, DNA recognition requires DNA single strands to be bonded to the FET active zone. At this aim, ammination of the diamond surface is needed. In this work we report a XPS in situ study of direct nano-crystalline diamond ammination using ammonia gas in order to understand the chemical reaction that happens on the diamond surface.