SEM and Raman analysis of boron-doped diamond coating on spherical textured substrates A.F. Azevedo a, ⁎ , R.C. Mendes de Barros b , S.H.P. Serrano b , N.G. Ferreira a a Laboratório Associado de Sensores e Materiais–LAS/INPE, Av. dos Astronautas, 1758, Jardim da Granja, São José dos Campos/SP, CEP.12245-970, Brazil b Instituto de Química–IQ/USP, Av. Lineu Prestes, 748, Bloco 2 Superior, Cidade Universitária, São Paulo/SP, CEP.05508-900, Brazil Received 22 March 2005; accepted in revised form 12 September 2005 Available online 26 October 2005 Abstract In this work boron-doped diamond (BDD) films were grown on new geometric form substrate. A laser texturized pretreatment on these substrates has promoted a better adherence between film and substrate, and a decrease of diamond total stress. Films morphology, obtained from Scanning Electron Microscopy (SEM) images, have showed that diamond average grain size, between 10–15 μm, decreased when the boron doping level was increased. For the micro-Raman spectroscopy, spectra analyses performed on each sample have allowed the residual stress evaluation and the diamond purity, from diamond and graphitic Raman peaks shifts. In these films, residual stress increased from 0.2 to 1.2 GPa and diamond purity decreased from 99.6% to 92.6% as the doping level increased. A specific study of morphology, total stress and diamond purity as a function of methane concentration was done for diamond film doped with 10,000 ppm B / C. It was observed a significant increase of grain size and total stress but little variation of diamond purity as methane concentration was increased. All these results gave us support for the use of these devices in different applications. © 2005 Elsevier B.V. All rights reserved. Keywords: Spherical boron doped diamond; Stress; Diamond purity 1. Introduction The determination of the mechanical and surface properties of coatings deposited on a substrate is important with regard to physical models and technical applications. The extreme CVD- diamond properties, and its feasibility of obtaining on different substrates, make this material a good candidate for a great number of novel applications. However, in order to grow films with uniform thickness and adherents, it is important to provide a constant temperature over the substrate area, a problem that becomes more acute when the substrate is spherical [1]. Besides, the residual stress is an important aspect because it may influence not only the adhesion between coating and substrate, but also the maximum thickness to which coatings can be grown, the roughness and the fatigue properties [2]. Fries and Vohra [3] using a microwave plasma reactor deposited nanostructured diamond films on curved surfaces of Ti6Al4V alloy machined to simulate the shape of a temporomandibular joint (TMJ) dental implant. Their results showed that deposited films are ultra-hard, adherents and uniform in chemical deposition along the curvature radius of TMJ condyle. For boron-doped diamond films, adherence becomes a limita- tion to get highly doped electrodes for using in electrochemical analysis with corrosive solutions. Residual stress control of these films is very important due the boron incorporation on substitutional or interstitial sites produce stress according to the doping level [4].The purpose of this study was to evaluate the morphology, crystalline size, quality, stress and diamond content of diamond films grown on spherical substrate surface. 2. Experimental procedure Boron-doped diamond films were grown on 1 mm dia- meter spherical tipped molybdenum rods using a hot- Surface & Coatings Technology 200 (2006) 5973 – 5977 www.elsevier.com/locate/surfcoat ⁎ Corresponding author. Tel.: +55 12 3945 6905; fax: +55 12 3945 6717. E-mail address: adriana@las.inpe.br (A.F. Azevedo). 0257-8972/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.surfcoat.2005.09.012