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Simulated STM images of several common defects on the (0001) surface of MoS2

Metallic nanoclusters on semiconductors are important for applications in nanoelectronics, catalysis, solar cells, and for study of the novel phenomena created by geometrical restrictions. To study their electronic properties, these clusters are typically grown on semiconductor surfaces such as molybdenite (MoS2). The presence of defects on the surface influences the nucleation and growth of metallic nanoclusters and their electronic properties can vary depending on the substrate.

The atomic resolution of the STM is an excellent tool to visualize clusters on MoS2 (see simulated STM image) and the bright spots in the image are generally associated with atoms. However, this is not necessarily always the case — the challenge is to correctly assign the atomic structure to the visualized surface features, making modeling necessary to assist in interpreting the images. As became apparent from the work of Professor Jorge Sofo at PSU, graduate student Javier Fuhr (currently at CRMCN-Marseille, France), and collaborator Andrés Saúl from CRMCN-Marseille, the combination of STM images and modeling may not be enough. They propose the additional use of scanning tunneling spectroscopy (STS) for the correct identification of surface features such as the chemical signature of naturally occurring defects.

This research area provides opportunities for undergraduate research.

Publications

1999 · 2002 · 2004 · All
J. D. Fuhr, A. G. Saúl and J. O. Sofo, "STM chemical signature of point defects on the MoS2(0001) surface," Phys. Rev. Lett. 92, 026802 (2004)
J. D. Fuhr, J. O. Sofo and A. G. Saúl, "Coverage dependence study of the adsorption of Pd on MoS2(0001)," Surf. Sci. 506, 161 (2002)
J. D. Fuhr, J. O. Sofo and A. G. Saúl, "On the adsorption of Pd on MoS2(0001) :ab initio electronic structure calculations," Phys. Rev. B 60, 8343 – 8347 (1999)
J. O. Sofo : Simulation of STM on MoS2(0001)