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Full-Text Articles in Chemistry

Semiconductor Nanowire Laser And Nanowire Waveguide Electro-Optic Modulators, Andrew B. Greytak, Carl J. Barrelet, Yat Li, Charles M. Lieber Oct 2005

Semiconductor Nanowire Laser And Nanowire Waveguide Electro-Optic Modulators, Andrew B. Greytak, Carl J. Barrelet, Yat Li, Charles M. Lieber

Faculty Publications

Electric field modulation of visible and ultraviolet nanoscale lasers consisting of single CdS or GaN nanowires has been achieved using integrated, microfabricated electrodes. Modulation of laser emission intensity is achieved with no detectable change in the laser wavelength. The devices can also be operated below the lasing threshold to modulate the intensity of light propagating within the nanowire waveguide. Studies of the electric field dependence in devices of varied geometry indicate that modulation is due to an electroabsorption mechanism. These findings expand opportunities for multicolor, nanowire-based photonic devices and circuits.


Mechanism Of Structural Transformation In Bismuth Titanate, Sudhanshu Mallick, Keith J. Bowman, Alexander H. King Jan 2005

Mechanism Of Structural Transformation In Bismuth Titanate, Sudhanshu Mallick, Keith J. Bowman, Alexander H. King

Alexander H. King

Sodium-doped bismuth titanate undergoes a transformation from Bi4Ti3O12 to Na0.5Bi4.5Ti4O15 on heating in air at temperatures exceeding 800 °C. This transformation proceeds through the intermediate Na0.5Bi8.5Ti7O27 structure which is an intergrowth phase of the two. High-resolution transmission electron microscopy was used to study this transformation. From the Moiré pattern that was obtained, the crystallographic orientation of the transformation front has been determined and a mechanism is proposed for this structural transformation.