Electronic structure of the SiN{sub x}/TiN interface: A model system for superhard nanocomposites

Journal Article · Tue Mar 15 00:00:00 EDT 2011 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.83.125124· OSTI ID:21538196

Patscheider, Joerg ^[1]; Hellgren, Niklas ^[2]; Haasch, Richard T; Petrov, Ivan; Greene, J E ^[2]

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1. EMPA, Laboratory for Nanoscale Materials Science, Ueberlandstrasse 129 CH-8600 Duebendorf (Switzerland)
2. Department of Materials Science and Frederick Seitz Materials Research Laboratory University of Illinois, 104 S. Goodwin Avenue, Urbana, Illinois 61801 (United States)

Nanostructured materials such as nanocomposites and nanolaminates--subjects of intense interest in modern materials research--are defined by internal interfaces, the nature of which is generally unknown. Nevertheless, the interfaces often determine the bulk properties. An example of this is superhard nanocomposites with hardness approaching that of diamond. TiN/Si{sub 3}N{sub 4} nanocomposites (TiN nanocrystals encapsulated in a fully percolated SiN{sub x} tissue phase) and nanolaminates, in particular, have attracted much attention as model systems for the synthesis of such superhard materials. Here, we use in situ angle-resolved x-ray photoelectron spectroscopy to probe the electronic structure of Si{sub 3}N{sub 4}/TiN(001), Si/TiN(001), and Ti/TiN(001) bilayer interfaces, in which 4-ML-thick overlayers are grown in an ultrahigh vacuum system by reactive magnetron sputter deposition onto epitaxial TiN layers on MgO(001). The thickness of the Si{sub 3}N{sub 4}, Si, and Ti overlayers is chosen to be thin enough to insure sufficient electron transparency to probe the interfaces, while being close to values reported in typical nanocomposites and nanolaminates. The results show that these overlayer/TiN(001) interfaces have distinctly different bonding characteristics. Si{sub 3}N{sub 4} exhibits interface polarization through the formation of an interlayer, in which the N concentration is enhanced at higher substrate bias values during Si{sub 3}N{sub 4} deposition. The increased number of Ti-N bonds at the interface, together with the resulting polarization, strengthens interfacial bonding. In contrast, overlayers of Si and, even more so, metallic Ti weaken the interface by minimizing the valence band energy difference between the two phases. A model is proposed that provides a semiquantitative explanation of the interfacial bond strength in nitrogen-saturated and nitrogen-deficient Ti-Si-N nanocomposites.

• OSTI ID: 21538196
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 83, Issue 12; Other Information: DOI: 10.1103/PhysRevB.83.125124; (c) 2011 American Institute of Physics; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COMPOSITE MATERIALS
DEPOSITION
ELECTRONIC STRUCTURE
EPITAXY
HARDNESS
INTERFACES
LAYERS
MAGNESIUM OXIDES
MAGNETRONS
NANOSTRUCTURES
NITROGEN
POLARIZATION
SILICON NITRIDES
SIMULATION
SPUTTERING
SUBSTRATES
THICKNESS
TITANIUM NITRIDES
X-RAY PHOTOELECTRON SPECTROSCOPY
ALKALINE EARTH METAL COMPOUNDS
CHALCOGENIDES
CRYSTAL GROWTH METHODS
DIMENSIONS
ELECTRON SPECTROSCOPY
ELECTRON TUBES
ELECTRONIC EQUIPMENT
ELEMENTS
EQUIPMENT
MAGNESIUM COMPOUNDS
MATERIALS
MECHANICAL PROPERTIES
MICROWAVE EQUIPMENT
MICROWAVE TUBES
NITRIDES
NITROGEN COMPOUNDS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PNICTIDES
SILICON COMPOUNDS
SPECTROSCOPY
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS