Ni-mediated reactions in nanocrystalline diamond on Si substrates: the role of the oxide barrier. Issue 14 (26th February 2020)

• Record Type: Journal Article
• Authors: Tulić, Semir; Waitz, Thomas; Romanyuk, Oleksandr; Varga, Marián; Čaplovičová, Mária; Habler, Gerlinde; Vretenár, Viliam; Kotlár, Mário; Kromka, Alexander; Rezek, Bohuslav; Skákalová, Viera
• Is Part Of: RSC advances. Volume 10:Issue 14(2020)
• Page Start: 8224
• Page End: 8232
• Publication Date: 2020-02-26
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d0ra00809e
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Nanocrystalline diamond films grown on Si/native oxide substrates were subjected to Ni-mediated graphitization. Transmission electron microscopy study revealed crystals of NiSi2 and SiC across the carbon/silicon interface in addition. Abstract : Nanocrystalline diamond (NCD) films grown on Si substrates by microwave plasma enhanced chemical vapor deposition (MWPECVD) were subjected to Ni-mediated graphitization to cover them with a conductive layer. Results of transmission electron microscopy including electron energy-loss spectroscopy of cross-sectional samples demonstrate that the oxide layer on Si substrates (∼5 nm native SiO2 ) has been damaged by microwave plasma during the early stage of NCD growth. During the heat treatment for graphitizing the NCD layer, the permeability or absence of the oxide barrier allow Ni nanoparticles to diffuse into the Si substrate and cause additional solid-state reactions producing pyramidal crystals of NiSi2 and SiC nanocrystals. The latter are found impinged into the NiSi2 pyramids but only when the interfacial oxide layer is absent, replaced by amorphous SiC. The complex phase morphology of the samples is also reflected in the temperature dependence of electrical conductivity, where multiple pathways of the electronic transport dominate in different temperature regions. We present models explaining the observed cascade of solid-state reactions and resulting electronic transport properties of such heterostructures.