Epitaxial Mechanism of Diamond Crystal Nucleation on a Mo {110} Substrate during Chemical Vapor Deposition
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STRUCTURE OF CRYSTALS
Epitaxial Mechanism of Diamond Crystal Nucleation on a Mo {110} Substrate during Chemical Vapor Deposition E. A. Zheligovskayaa,*, N. A. Bulienkova, and A. N. Blaut-Blacheva a Frumkin
Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, 119071 Russia *e-mail: [email protected] Received September 6, 2018; revised September 6, 2018; accepted November 14, 2018
Abstract—The epitaxial mechanism of diamond crystal nucleation by the (110) face on the Mo(110) face during chemical vapor deposition on a molybdenum plate has been established. It is shown that, under the synthesis conditions in use, only cubic sectors of diamond crystals continue to grow according to the tangential mechanism, whereas octahedral sectors are characterized by some complex nonequilibrium mechanism of normal growth. In particular, a situation where the {111} faces are absent and octahedral sectors grow by {100} layers of three orientations, which make a reentrant cube angle and are twins of the initial crystal on one of its {111} faces, has been observed. Geometric analysis of five-fold aggregates of multiply twinned diamond crystals with a shared 110 axis shows that at least one narrow truncating lateral {111} face oriented parallel to the shared 110 axis should occur. DOI: 10.1134/S1063774519060270
INTRODUCTION The morphology of individual diamond crystals or crystallites entering diamond films grown by chemical vapor deposition depends strongly on the synthesis conditions: substrate temperature, structure and method of preliminary treatment of the substrate surface, gas mixture pressure, concentration of the carbon-containing component in the mixture, and synthesis duration [1]. To date, for different purposes, a number of techniques have been developed to grow diamond films consisting of crystallites of different morphology by varying the chemical vapor deposition conditions. For example, promising ways of preparing single-crystal diamond plates with a large (100) surface were considered in [2]. Such diamond plates are highly demanded in electronics. On the contrary, polycrystalline diamond films with axial 100 texture were used in [3, 4], because their selective oxidation provides needle-like diamond single crystals with a sharp pyramidal form. It is known that the use of the (111) and (100) faces of various metals as substrates (Pt(111), Pd(111), Ir(100), Ni(111), Ni(100), etc.) leads to diamond crystal nucleation according to the epitaxial mechanism [1]. In this study, we established that diamond crystals are nucleated by the (110) face on the Mo(110) face according to the epitaxial mechanism and showed a difference in the mechanisms of further growth of their cubic and octahedral sectors under the chemical vapor deposition conditions in use.
Growth of diamond crystals during chemical vapor deposition is generally accompanied by numerous twinnings with {111} twin planes. Possible types of the morphology of twin diamond crystals, in which the twin component nucleates on a fa
