The fractal dimension of boron-doped diamond films

Boron-doped diamond films were grown by hot-filament-assisted chemical vapor deposition (CVD). The fractal dimension (FD) of these films was investigated by atomic force microscope and cyclic voltammetry. The scaling behavior is measured for peak current in cyclic voltammetry, height-height correlations and island size distribution in AFM images. Cyclic voltammetry experiments and the mass-radius (or island distribution) analysis have evidenced FD values lower than two suggesting non-contiguous chemically active sites. (C) 2001 Elsevier Science B.V. All rights reserved.1814173232733

Synchrotron radiation X-ray analysis of boron-doped diamond films grown by hot-filament assisted chemical vapor deposition

This paper presents a synchrotron X-ray radiation analysis of boron-doped diamond films grown by hot-filament assisted chemical vapor deposition (HFCVD). The diamond films were grown at different doping levels with the introduction of boron to the gas mixture by bubbling hydrogen in a B2O3 solution in methanol. The B/C ratio in methanol varied from 2000 to 20 000 ppm and the gas flow rates were controlled so that boron incorporation to the film varied in the range from 10(18) to 10(21) boron/ cm(3). All other process parameters were kept unchanged to allow comparison only of the influence of the doping level. The film. analyses were performed at the X-ray diffraction beamline of the Laboratorio Nacional de Luz Sincrotron - LNLS, Brazil. The Debye-Scherrer configuration was used in this study. A high intensity monochromatic beam at lambda = 1.46 A was used and an excellent signal to noise ratio was obtained for 2theta varying from 20degrees to 150degrees. The difractogram for the undoped diamond film show intense peaks from the (111), (220), (311), (400) and (331) crystallographic planes. For the boron-doped films a set of new diffraction lines appear and their intensities increase considerably with the doping level. The set of diffraction peaks of similar intensities are related to a hexagonal structure and were assigned with hi-h confidence to tungsten carbide. This reveals that the boron-doping process in HFCVD facilitates the incorporation of tungsten carbide from the filament in the diamond film. The FWHM analysis of the diamond diffraction peaks shows a dependence of film crystallinity with doping level with a definite maximum at approximately 2.3 X 10(19) boron/cm(3). (C) 2002 Elsevier Science B.V. All rights reserved.11215315