Growth and characterization of combined single-crystalline and polycrystalline CVD diamond wafer
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Growth and characterization of combined single-crystalline and polycrystalline CVD diamond wafer A.L. Vikharev, A.B. Muchnikov, D.B. Radishev, V.A. Isaev, O.A. Ivanov, A.M. Gorbachev Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov Street, Nizhny Novgorod, 603950, Russia ABSTRACT The study of combined single-crystalline and polycrystalline chemical vapor deposited (CVD) diamond wafers is reported. Combined CVD diamond wafers up to 75 mm in diameter were grown, which consist of great number of single-crystalline diamond sections grafted in a polycrystalline diamond matrix. The grown combined CVD wafers were characterized by the Raman spectroscopy. It was shown that in the grafting process, the single- and polycrystalline areas of the combined wafer undergo insignificant stresses, which can be released during the thermal annealing process. Fabricated combined CVD diamond can be used in various applications that employ unique properties of diamond and potentially suitable for industrial use. INTRODUCTION Diamond is a promising material having a set of exceptional properties, which allow one to regard it as a high-technology material for a wide range of scientific and industrial applications, including those used to develop high-frequency and high-power electronic devices. In terms of its structure, diamond can be single- or polycrystalline. Polycrystalline diamond grown by the chemical vapor deposition (CVD) technology consists of a great number of coalescent crystallites or grains. Currently, polycrystalline CVD diamond is available in the form of wafers with diameters up to 150 mm [1-3] and is quite suitable for industrial applications. The properties of single-crystalline diamond (SCD) exceed those of polycrystalline one, since it has no grain boundaries. However, most common dimensions of single-crystalline CVD diamond plates range from 3x3 to 5x5 mm. The manufacturing technology of single-crystalline CVD diamond with larger areas is still being developed yet [4-8]. At present, the size of the largest wafer of mosaic CVD diamond (several CVD “clone wafers” aligned and grown together) is 40x60 mm [9]. The production of a combined wafer of single- and polycrystalline CVD diamond (i.e., a wafer of polycrystalline diamond with intrusions of single-crystalline diamond grafted in it [10]) can be an alternative for the tiling of several CVD diamond crystals into one wafer. The use of the combination of single- and polycrystalline CVD diamond will allow one to expand the application range of small-size single-crystalline plates significantly. For example, the technological tools, which were developed for silicon device engineering, can be used to produce electronic devices based on combined wafers that have diameters up to 150 mm. The active element of such devices can be fabricated on the single-crystalline diamond section, whereas the “matrix” of polycrystalline diamond will function as a support with high heat conductivity. This paper presents the results of studying the method of producing wa
