Nanomechanics of silicon surfaces with atomic force microscopy: An insight to the first stages of plastic deformation

Abstract

The use of stiff cantilevers with diamond tips allows us to perform nanoindentations on hard covalent materials such as silicon with atomic force microscopy. Thanks to the high sensitivity in the force measurements together with the high resolution upon imaging the surface, we can study nanomechanical properties. At this scale, the surface deforms, following a simple non-Hertzian spring model. The plastic onset can be assessed from a discontinuity in the force-distance curves. Hardness measurements with penetration depths as small as 1 nm yield H= approximately 25 GPa, thus showing a drastic increase with penetration depths below 5 nm.

Investigation of the interaction between Tc85-11 protein and antibody anti-T. cruzi by AFM and amperometric measurements

“…The silicon-gold slides were annealed up to 1000 • C for 5 s to obtain atomically flat Au (1 1 1) crystals on the surface [16]. First, the gold surface was immersed in a 20 mM cystamine solution for 2 h. After washing the surface with MilliQ water, the gold substrate with a cystamine self-assembled layer (SAM) was immersed in a 0.25% glutaraldehyde solution during 1 h and the surface again was washed with MilliQ water.…”

“…Digital NanoScope software (v 4.22) was used to analyze the topographic images. The gold substrates used in AFM imaging, are prepared by depositing a gold layer either on silicon or on Si 3 N 4 slides using a sputter system (Sputter Coater S150B, BOC Edwards, UK) followed by a thermal annealing [16].…”

First-principles calculation of mechanical properties of Si⟨001⟩ nanowires and comparison to nanomechanical theory

“…Hence, it is less important for hydrogenated Si surfaces, where the hydrogen-hydrogen interaction is prominent as evidenced in the surface (ground-state) structures. 56,59 The efforts to understand the surface mechanics using experimental 60 and simulated 61 nanoindentation provide qualitative descriptions but the accurate (size-dependent) Young's modulus or the surface elastic constants have proved difficult to access via this indirect technique, leading to a need for direct measurement. In the work presented here first-principles calculations are crucial to deal properly with quantum mechanical effects such as the hydrogen-hydrogen interaction, and to investigate directly the size-dependent mechanical properties of the hydrogenated surface in a quantitative sense.…”

Modulus and Hardness Change of Silicon and Sapphire Substrates by TiC/VC Multilayer Coatings

“…Both materials have become attractive as part of electronic devices. The following nanohardness values H have been reported for single crystalline silicon: H = 13 GPa for (100) and 16 GPa for (111) surfaces [12]. (0001) surfaces of sapphire exhibited H = (29.1 ± 0.1) GPa [13] at a depth of 200 nm.…”