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R S Balmer,
I Friel,
S M Woollard, C J H Wort,
G A Scarsbrook,
S E Coe,
H El-Hajj,
A Kaiser,
A Denisenko,
E Kohn,
J Isberg
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ABSTRACT: In this paper, we review the suitability of diamond as a semiconductor material for high-performance electronic applications. The current status of the manufacture of synthetic diamond is reviewed and assessed. In particular, we consider the quality of intrinsic material now available and the challenges in making doped structures suitable for practical devices. Two practical applications are considered in detail. First, the development of high-voltage switches capable of switching voltages in excess of 10 kV. Second, the development of diamond MESFETs for high-frequency and high-power applications. Here device data are reported showing a current density of more than 30 mA mm(-1) along with small-signal RF measurements demonstrating gigahertz operation. We conclude by considering the remaining challenges which will need to be overcome if commercially attractive diamond electronic devices are to be manufactured.
Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences 02/2008; 366(1863):251-65. · 2.77 Impact Factor
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ABSTRACT: Diamond is a unique optical material having the combination of high strength and transparency in the visible, near and far infrared regions. As a far infrared window it has already found applications in demanding environments, e.g. high-power CO2 laser exit windows. In this paper, the far infrared optical properties of diamond are described together with the near infrared properties and the potential for using CVD diamond at shorter wavelengths is discussed. How such optical properties as absorption, scatter and image quality are related to the characteristics of CVD diamond are described. The far infrared absorption properties of diamond at elevated temperatures are presented and the mechanisms that cause the residual absorption and its temperature dependence in this region are discussed. An empirical formula for predicting the temperature-dependent absorption coefficient is presented.
Semiconductor Science and Technology 02/2003; 18(3):S117. · 1.72 Impact Factor
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ABSTRACT: Defects in free-standing diamond films grown by microwave-plasma-assisted chemical vapour deposition have been studied by electron paramagnetic resonance (EPR). The EPR spectra observed for the as-grown material each consisted of two distinguishable Lorentzian lines at g = 2.0028(2), along with weak satellites centred on g = 2.0028 and separated from each other by 1.15 - 1.35 mT. Comparison of the local concentration (up to 500 ppm) determined by lineshape analysis and the bulk concentration (0.3 - 8 ppm) determined from the total EPR absorption revealed that the defects were inhomogeneously distributed in the diamond film. Multi-frequency EPR measurements showed that the satellite separation depended on the microwave frequency. It is proposed that the satellite lines originate from a pair of coupled electron spins which form a biradical centre. This appears to be the only model which is consistent with the observed microwave frequency dependence of the satellite separation.
Journal of Physics Condensed Matter 12/1998; 8(7):837. · 2.55 Impact Factor
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R. S. Sussmann,
C. S. J. Pickles,
J. R. Brandon, C. J. H. Wort,
S. E. Coe,
A. Wasenczuk,
C. N. Dodge,
A. C. Beale,
A. J. Krehan,
P. Dore,
A. Nucara,
P. Calvani
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ABSTRACT: This paper describes the attributes that make diamond a unique material for infrared synchrotron beam experiments. New developments
in diamond synthesised by Chemical Vapour Deposition (CVD) promise to extend the range of applications which have been hitherto
limited by the availability and cost of large-size single-crystal diamond. Polycrystalline CVD diamond components such as
large (100 mm) diameter windows with extremely good transparency over a wide spectral range are now commercially available.
Properties of CVD diamond of relevance to optical applications, such as mechanical strength, thermal conductivity and absolute
bulk absorption, are discussed. It is shown that although some of the properties of CVD diamond (similar to other polycrystalline
industrial ceramics) are affected by the grain structure, currently produced CVD diamond optical components have the quality
and performance required for numerous demanding applications.
PACS 81.05.TpFullerenes and related materials diamond, graphite
PACS 42.79.CiFilters, zone plates, and polarizers
PACS 78.30Infrared and Raman spectra
PACS 01.30.CcConference proceedings
Il Nuovo Cimento D 04/1998; 20(4):503-525.
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ABSTRACT: Considerable progress has been made in recent years on the synthesis of diamond by chemical vapour deposition (CVD) leading to substantial improvements in material quality and rate of synthesis. As a result it has been possible to manufacture relatively thick plates of free-standing bulk polycrystalline CVD diamond removing many of the limitations of thin-film coatings. This exploit has promoted CVD diamond from experimental novelty to a true engineering material opening a wide range of applications in which the unique properties of diamond can be used. This paper reports on a range of properties of bulk polycrystalline CVD (BPCVD) diamond. The material used in these experiments is synthesized and processed under routine manufacturing conditions rather than as isolated research specimens. Most of the specimens used have been made flat and parallel and have been polished to an optical quality finish. Many of the properties are influenced by surface conditions and it is important to emphasise that after-growth processing is an integral part of what is referred to in this paper as BPCVD diamond specimens. The following properties are reviewed: optical properties; thermal properties; mechanical properties; dielectric properties; and laser induced damage threshold
Diamond in Electronics and Optics, IEE Colloquium on; 12/1993
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ABSTRACT: This paper reports the bursting strength and Young's modulus values for bulk polycrystalline chemical vapour deposited (BP CVD) diamond using a differential pressure technique. The pressure-deflection data have a linear relationship and are analysed using plate theory. The results are presented for BP CVD diamond discs (14 and 25 mm in diameter and 179–319 μm thick), silicon, gallium arsenide and sapphire. Young's modulus values with a range of 986–1079 GPa and bursting strengths of 746–1138 MPa were calculated for BP CVD diamond.
Diamond and Related Materials.
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ABSTRACT: Laser-induced damage threshold (LIDT) measurements have been made on bulk polycrystalline (BP) CVD diamond plates using 0.532, 1.06 and 10.6 μm radiation and compared with measurements on natural type IIa diamond samples. Using 10.6 μm radiation, damage thresholds for BP CVD diamond have been measured as 5.6–12.7 MW mm−2 (29–66 J cm−2) using a 50 ns laser spike. These values compare with measurements in type IIa diamond of 12.5–18.5 MW mm−2 made in this study, and values of 3.5–40 MW mm−2 reported elsewhere.The LIDTs measured show a strong correlation with bulk absorption, which is significant at 0.532 μm, and with sample surface finish, but poor correlation with the carbonaceous inclusions found in the samples. Extrapolation from the d.c. dielectric breakdown threshold to the time domain of interest would suggest that, in both current CVD diamond and type IIa single-crystal natural diamond, the damage threshold is being substantially reduced by material or sample imperfections.
Diamond and Related Materials.
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ABSTRACT: Properties are reported of bulk polycrystalline diamond synthesized by chemical vapour deposition (BPCVD diamond). It is shown that this material exhibits optical and thermal properties similar to those of high purity natural Type IIa diamond. The mechanical strength and elastic properties of this material have been measured by a disc-bursting technique and values of bursting strength of up to 1138 MPa and Young's modulus values of 986–1079 GPa have been observed. Indentation measurements indicate a value for fracture toughness K1c of 6MP a m1/2. The dielectric constant and dielectric loss have been measured by an open resonator technique at frequencies of 36, 72 and 144 GHz. Bulk values of dielectric loss tangent as low as 73 × 10−6 have been observed, the lowest so far reported for CVD diamond. The threshold to laser damage has been tested at laser wavelengths of 10.6, 1.06 and 0.532 μm. Damage thresholds are found to be influenced by bulk absorption. However, the best values measured in BPCVD diamond at 10.6 μm approach that of natural Type IIa diamond.
Diamond and Related Materials.
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ABSTRACT: The thermal properties of bulk polycrystalline CVD diamond are presented and correlated with measured optical properties. A technique for measuring thermal diffusivity is described, and measurements of thermal conductivity as a function of temperature are reported. UV, visible, Fourier transform IR (FTIR) and Raman spectroscopies were used to assess the quality of bulk polycrystalline diamond plates produced by chemical vapour deposition (CVD), which is compared with that of type IIa natural diamond. The refractive index at a wavelength of 10.0 μm was measured as 2.375 ± −0.014, which is in good agreement with the value of 2.3756 accepted for type IIa natural diamond. For colourless, transparent CVD diamond plates, the absorption coefficient in the 8–14 μm wavelength region is between 0.1 and 0.3 cm−1. The data presented show that the thermal and optical properties of CVD diamond with thermal conductivities between 4 and 16.5 W cm K−1 are dictated by the quantity of impurity phases. However, other mechanisms dominate in the very highest quality polycrystalline CVD diamond plates. In these, values of thermal conductivity (up to 21 W cm−1 K−1 at 300 K) and optical transmission (71.3% in the IR and 68% in the visible) approaching those of natural type IIa diamond are achieved.
Diamond and Related Materials.
