Scanning gate microscopy of current-annealed single layer graphene

We have used scanning gate microscopy to explore the local conductivity of a current-annealed graphene flake. A map of the local neutrality point (NP) after annealing at low current density exhibits micron-sized inhomogeneities. Broadening of the local e-h transition is also correlated with the inhomogeneity of the NP. Annealing at higher current density reduces the NP inhomogeneity, but we still observe some asymmetry in the e-h conduction. We attribute this to a hole-doped domain close to one of the metal contacts combined with underlying striations in the local NP. © 2010 American Institute of Physics.

Observation of the ordered growth of coronene on Ag(111): a scanning tunnelling microscopy study of vacuum deposited molecules

The molecular ordering of coronene (C24H12) obtained by vacuum-deposition onto predominantly Ag(111) on mica has been investigated using the scanning tunnelling microscope. Real-space topographic images reveal that in certain regions we obtain layer-by-layer ordered growth of the molecules on this substrate which agrees with previous indirect measurements (the growth did not display this ordering in other regions). In our experiments on the ordered regions, we observe the best imaging contrast at a voltage bias of -0.28 V which may correspond to a resonant tunnelling process through the molecules. © 1995.

Scanning transmission electron microscopy investigation of the Si(111)/AlN interface grown by metalorganic vapor phase epitaxy

The structure and chemistry of the interface between a Si(111) substrate and an AlN(0001) thin film grown by metalorganic vapor phase epitaxy have been investigated at a subnanometer scale using high-angle annular dark field imaging and electron energy-loss spectroscopy. 〈1120̄〉AlN ∥ 〈110〉Si and 〈0001〉AlN ∥ 〈111〉 Si epitaxial relations were observed and an Al-face polarity of the AlN thin film was determined. Despite the use of Al deposition on the Si surface prior to the growth, an amorphous interlayer of composition SiNx was identified at the interface. Mechanisms leading to its formation are discussed. © 2010 American Institute of Physics.

Field of view expansion for 3-D holographic display using a single spatial light modulator with scanning reconstruction light

Increasing the field of view of a holographic display while maintaining adequate image size is a difficult task. To address this problem, we designed a system that tessellates several sub-holograms into one large hologram at the output. The sub-holograms we generate is similar to a kinoform but without the paraxial approximation during computation. The sub-holograms are loaded onto a single spatial light modulator consecutively and relayed to the appropriate position at the output through a combination of optics and scanning reconstruction light. We will review the method of computer generated hologram and describe the working principles of our system. Results from our proof-of-concept system are shown to have an improved field of view and reconstructed image size. ©2009 IEEE.