Effect of crystal plane orientation on tribochemical removal of monocrystalline silicon

Abstract

The effect of crystal plane orientation on tribochemical removal of monocrystalline silicon was investigated using an atomic force microscope. Experimental results indicated that the tribochemical removal of silicon by SiO2 microsphere presented strong crystallography-induced anisotropy. Further analysis suggested that such anisotropic tribochemical removal of silicon was not dependent on the crystallography-dependent surface mechanical properties (i.e., hardness and elastic modulus), but was mainly attributed to various atomic planar density and interplanar spacing in different crystal planes. Phenomenological results speculated that higher density of silicon atom could promote the formation of Si-O-Si bonds between the SiO2 microsphere and silicon substrate, resulting in more severe tribochemical material removal. Larger interplanar spacing with smaller energy barrier facilitated the rupture of the Si-Si network with the help of mechanical shearing stress, which caused more serious wear of the silicon surface. The results may help understand the material removal mechanism of silicon and provide useful knowledge for chemical mechanical polishing.

Effect of Humidity on Friction and Wear—A Critical Review

“…These results suggest that the chemistry of the counter surface (SiO2 vs. diamond) plays an important role in the wear of materials [163]. On the Si-H surface, as humidity increases, friction decreases monotonically, but wear increases initially, reaches a maximum value, and then eventually decreases [161,162,164]. In contrast, on the SiOx surface, both friction and wear first increase to a maximum value at 50% RH and then decrease below the detection limit of AFM at RH above 85% or in water (Figure 7a) [163,[165][166][167][168][169][170][171].…”

“…It is also noted that the effect of humidity on wear of SiO x -covered Si wafer varies depending on the sliding speed ( Figure 7b) [168]. SiOx surfaces show excellent wear resistance in dry condition, when the applied shear stress is lower than the yield stress of the substrate, regardless of counter-surface materials (active SiO2 and inert diamond) [158][159][160][161][162]. As humidity increases, wear occurs on Si-H and SiOx surfaces when the counter surface is SiO2, but wear is negligible when the counter surface is diamond at the same loading conditions.…”

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

“…Finally, besides interfacial forces, surface wear caused by frictional shear stress is likely to complicate the dynamics [4,159]. Tribochemical reactions may occur between water molecules and the solid surface when the activation energy of these reactions is reduced by an external mechanical action [5,[160][161][162][163][164][165][166][167]. The structure and surface energy of the adsorbed water layer on dynamically changing tribological interfaces may also play vital roles in the mechanochemistry involved in the material removal phenomenon.…”

Fast room-temperature functionalization of silicon nanoparticles using alkyl silanols

“…This corresponds to literature values found for crystalline silicon wafers (3.13 and 1.92Å, respectively). 42 Recently, a paper by Oliinyk et al raised the question whether Si NPs could really be formed in a microwave reaction. 43 Even though they specically doubted their formation in an aqueous solution, and suggested the formation of uorescent NPs of a carbon or hybrid composition, their investigation is also relevant here.…”