A monolayer of fullerene molecules on Si(111) surfaces is fabricated in an ultrahigh vacuum chamber through a controlled self-assembly process. The characteristics of self-assembled Si(111) surfaces, including supramolecular structures, electronic density of states, the quantum confinement effect, field emission features, and optoelectronical properties with embedded C 84 are determined by the use of an ultrahigh vacuum scanning probe microscope. The results revealed that such a silicon surface with embedded C 84 has a wide band gap of y3.4 eV, high emission efficiency and low turn-on voltage, all of which are crucial to nano-electronics, optoelectronics, and the fabrication of semiconductor carbide. The measured data derived from photoluminescence emission experiments further confirm the corresponding band gap value obtained from I-V curves. The theoretical results from first-principles calculations for the field enhancement factor are compared with experimental measurements.
This study describes the feasibility of fabricating of a single layer of fullerene embedded Si surface through a controlled self-assembly mechanism in an ultrahigh vacuum (UHV) chamber. The characteristics of the fullerene embedded Si surface are investigated directly using UHV-scanning probe microscopy. Additionally, the band gap energy and field emission parameters, including turn-on field and the field enhancement factor beta of the fullerene embedded Si substrate, are determined using a high-voltage source measurement unit and UHV-scanning tunneling microscopy, respectively. Moreover, the nanomechanical properties, which represent the stress of the fullerene embedded Si substrates, are assessed by an environment atomic force microscope (AFM) and UHV-AFM, respectively. Results of this study demonstrate that a single layer of the fullerene embedded surface has superior properties for nanotechnology applications owing to the ability to control the self-assembly mechanism of fabrication. (C) 2010 American Institute of Physics. [doi:10.1063/1.3475775
The nanoindentations of a silicon (111) substrate covered with a manipulated C 84 monolayer are explored by molecular dynamics (MD) simulation and further verified by experiments. Calculations show that pop-in events and a stick-slip event are exhibited in the C 84 /Si substrate during the loading process, where the pop-in events are caused by the severe deformation of the C 84 molecule, while the stick-slip event takes place at the interface between the tip and C 84 molecule. The resulting deformed conformations and mechanical properties influenced by the diverse indentation mechanisms are also presented. Such a nanoindentation simulation model provides a powerful way to understand at an atomic level the interaction of the parts of an interface, and of the system as a whole. The experimental measurements from ultra-high vacuum atomic force microscopy (AFM) are compared with theoretical findings. Our investigations offer a possible replacement for semiconductor carbide.
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