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Noncommensurate 2D interfaces hold great promise toward low friction and nanoelectromechanical applications. For identical constituents, the crystals interlock at specific rotational configurations leading to high barriers for slide. In contrast, nonidentical constituents comprising different lattice parameters should enable robust superlubricity for all rotational configurations. This is however not the case for gold-graphite interfaces, as both theory and experiments show scaling behavior of the sliding force as a function of the interface contact area. By simulating the sliding force for gold-graphite interfaces, this work shows that the origin for high force barriers at special angular configurations is a result of commensurability between the moiré structure and the contact geometry. Consequently, this paper suggests new geometries that can potentially overcome such commensurability effects to enable robust superlubricity.

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This article describes the implementation of VCSELs as light sources for a chip-scale, highly dense multi-channel transmitter and receiver. The VCSELs are implemented using flip chip technology, as part of a hybrid process for the fabrication of an integrated photonic chip, using standard semi-conductor processes. The results as published indicate that integrated photonic chips may be applicable for various high speed datacom applications where copper use is restricted.