Boron-doped diamond thin film deposition

J. Stotter, J. Zak, Z. Behier, Y. Show, G.M. Swain, Optical and electrochemical properties of optically transparent, boron-doped diamond thin films deposited on quartz, Anal. Chem., vol. 74, p.5924, 2002. 

The names for these two film types arise from their nominal crystallite size and morphology. Figure 5 shows scanning electron microscopy (SEM) images of the two types of boron-doped diamond thin film deposited on Si. High quality microcrystalline diamond films are deposited from CH4/H2 source gas mixtures with volumetric ratios of 0.3 to 1.0%,... 

Figure 17 shows cyclic voltammetric i-i curves for 1 and 25 pM horse heart cytochrome c in 50 mM NaCl -l- Tris HCl buffer, pH 7.2, at a boron-doped diamond thin film deposited on quartz. No faradaic response can be seen above the background for the 1 pM concentration but a well-defined, peaks-shaped response is seen for the 25 pM solution. At this can rate (0.1 V/s), the AFp is ca. 100 mV and is ca. 0.50 pA. The Zp /z ratio is near 1... 

One important electrochemical technology where diamond electrodes have made a significant impact is in the area of electroanalysis. CVD diamond offers advantages over other electrodes, especially sp carbon (e.g., glassy carbon), in terms of linear dynamic range, limit of detection, response time, response precision, and response stability. Some of the reported applications of diamond in electroanalysis are highlighted below. Unless stated otherwise, all the diamond electrodes mentioned below are boron-doped, microcrystalline thin films deposited on a conducting substrate (e.g.. Si). 

Preparation and Characterization of Poly crystalline Chemical Vapor Deposited Boron-doped Diamond Thin Films... 

Ivandini TA, Einaga Y, Honda K et al (2(X)5) Preparation and characterization of polycrystalline chemical vapor deposited boron-doped diamond thin films. In Fujishima A, Einaga Y, Rao TN, Tryk DA (eds) Diamond electrochemistry. Elsevier, Amsterdam, pp 11-25... 

Figure 23B presents IR transmission spectra for (5) an optically pure and mechanically polished white diamond disc, (6) an undoped and polished (both sides) Si substrate, and (7 and 8) moderately and heavily boron-doped microcrystalline diamond thin films deposited on the undoped Si. The white diamond is relatively free of structural defects and chemical impurities. There is reduced transparency between 2500 and 1500 cm due to the two-phonon absorption. Diamond films with more... 

FIG. 23. Transmission spectra for different materials in the (A) UV/Vis and (B) IR regions of the electromagnetic spectrum. The electrodes in (A) are (1) a thin film of ITO on quartz, (2) a thin film of boron-doped nanocrystalline diamond on quartz, (3) a thin film of mechanically polished and boron-doped diamond on an optically pure, white diamond substrate, and (4) a free-standing, boron-doped, and mechanically polished diamond disc. The electrodes in (B) are (5) an optically pure and mechanically polished white diamond disc, (6) an undoped and polished (both sides) Si substrate, and (7 and 8) moderately and heavily boron-doped microcrystalline diamond thin films deposited on the undoped Si. (Reprinted with permission from Interface 2003, 12, 33. Copyright (2003) The Electrochemical Society, Inc.) (From Ref. 158.)... 

Wang, S. H., Swain, G. M. Spatially heterogeneous electrical and electrochemical properties of hydrogen-terminated boron-doped nanocrystalhne diamond thin film deposited from an argon-rich CH/... 

Boron-doped chemical-vapor-deposited diamond is an exceptionally inert carbon electrode with a very wide potential window and very low voltammetric background current. [A. E. Fischer, Y. Show, and G. M. Swain, Electrochemical Performance of Diamond Thin-Film Electrodes from Different Commercial Sources, Anal. Chem. 2004, 76, 2553.]... 

Deguchi, M., Kitabatake, M. and Hirao, T. (1996), Electrical properties of boron-doped diamond films prepared by microwave plasma chemical vapour deposition. Thin Solid Films,... 

Thin-film electrode — An electrode covered with a thin film of a given substance. The purpose of placing a thin film on the electrode surface is to obtain desired electrode properties. Many different substances have been used to prepare film electrodes they include among others mercury (see - thin mercury film electrodes) gold, boron-doped diamond (see - boron-doped diamond electrode), conductive polymers (see - polymer-modified electrode), and alkanethiols. The film thickness can vary from several micrometers (mercury) to monomolecular layers (thiols). In some cases (e.g., for - spectroelectrochemistry purposes) very thin layers of either gold or tin oxide are vapor-deposited onto glass plates. Thin film electrodes are often called - surface-modified electrodes. 

Boron-doped diamond (BDD) thin films were synthesized at CSEM (Neuchatel, Switzerland) by the hot filament chemical vapor deposition technique (HF CVD) on p-type, low-resistivity (l-3mQcm), single-crystal, silicon wafers (Siltronix). The temperature of the filament was between 2440 and 2560 °C and that of the substrate was monitored at 830 °C. The reactive gas was a mixture of 1% methane in hydrogen, containing trimethylboron as a boron source (1-3 ppm, with respect to H2). The reaction chamber was supplied with the gas mixture at a flow rate of 51 min giving a growth rate of 0.24 pm h for the diamond layer. The obtained diamond film has a thickness of about 1 pm ( 10%) and a resistivity of 15mQcm ( 30%). This HF CVD process produces columnar, random textured, polycrystalline films [9]. 

Doped diamond is the alternative carbon material to glassy carbon for ozone generation [20,21], but the technology is much less developed. Boron-doped diamond is prepared by chemical vapor deposition and has been used as an anode when (i) deposited as a thin film on substrates such as silicon, titanium, or niobium or (ii) fabricated as a bulk plate - for example. Element Six supplies Diafilm EP as a free-standing polycrystalline plate capable of supporting current densities of >1 Acm [25]. Typically, the boron-doping concentration is 10 °-10 atoms cm when its resistivity is of the order of 0.05 cm. These boron-doped... 

FIG. 20. Cyclic voltammetric i-E curves for 1 mM CAD, along with the corresponding background current (dashed line), in a 0.01 M borax buffer, pH 11.2, at (A) a boron-doped nanocrystalline diamond thin-film electrode and (B) a nanocrystaUine diamond thin-film electrode deposited without intentionally... 

Another electrode form is a thin film deposited on an optically transparent nondiamond substrate, such as undoped Si for IR or quartz for UV/Vis spectroelectrochemical measurements. Diamond deposition on Si for IR OTEs is rather straightforward and involves growth conditions similar to those described above. The resulting films are 2-4 gm thick with micrometer-sized grains of diamond randomly oriented over the surface. Deposition of thin films of diamond on quartz is a little more involved [118]. Figure 22 shows an optical image of a diamond/quartz OTE. The film has a blue hue to it due to the boron doping level. It is... 

Industrial Applications Boron-doped diamond (BDD) substrates Langmuir-Blodgett films thin films vacuum-deposited films - ... 

The details of the growth of the boron-doped polycrystalline diamond thin films using a high pressure microwave plasma-assisted chemical vapor deposition system (ASTeX) have been... 

Meanwhile, diamond microfiber electrodes prepared via chemical vapor deposition on platinum wires have been fabricated and also reported as an amperometric detector in CE-ED analysis. Cvacka et al. [12] reported that boron-doped polycrystalline diamond thin films were deposited on electrochemically sharpened platinum wires, and similarly confirmed the advantages of the... 

Boron-doped diamond (BDD) thin films, grown on a suitable substrate (p-Si, Ti, Nb, W and Mo) by chemical vapor deposition, is a new electrode material that possesses a number of unique electrochemical properties, distinguishing them from other traditional electrodes [1-4], One of the most useful properties of the BDD diamond electrode is the possibility to electrogenerate hydroxyl radicals under polarization at high anodic potentials (eq.20.1). 

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