May 29, 2009
Fiber probe and nanoprobe techniques combined inside SEM
Comprehensive characterization of individual nanostructures and nanodevices can be performed by combining fiber probe and nanoprobe techniques inside a scanning electron microscope. This integrated system provides opportunity for the assembly and characterization of optoelectronic nanodevices in situ.
Recently, nanoscale light generation, routing, modulation and detection have been demonstrated using nanodevices based on one-dimensional optoelectronic nanomaterials. To get a thorough understanding of such nanodevices it is often necessary to characterize the microstructure, composition, and electrical and optical properties of the same individual nanostructure.
Researchers at Peking University have worked out an integrated approach to performing such a comprehensive characterization. The team's set-up combines optical fiber probe and nanoprobe techniques inside a scanning electron microscope (SEM) chamber. As shown in the above image, one or two fibre probes are attached to nano-manipulators, while the rest of the manipulators are fitted with nanometer-sized tungsten (W) tips for electrical measurements and nanomanipulation. The outside end of the fibre probe is coupled to either a spectrometer for light analysis or a laser for optical excitation. The space-saving design of the optical component inside the chamber permits the simultaneous action of the fibre probe and other SEM attachments. For example, an X-ray energy-dispersive spectrometer for composition characterization. Thus, comprehensive characterization of individual optoelectronic nanostructures and nanodevices can be carried out inside one chamber.
The flexibility of the integrated system means that the set-up can be used to assemble and characterize optoelectronic nanodevices in situ. For example, the researchers have demonstrated the assembly and characterization of a light emitter and photodetector based on individual nanowires. The scientists have also shown that the angular resolving power of the fibre-optical detection is particularly useful for characterizing the anisotropic light emitting properties (for example, nano-waveguide behaviour) of nanostructures.
The group presented its results in Nanotechnology.
About the author
Dr Min Gao is an associate professor in the Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics at Peking University. His current research interests are the characterization and fabrication of optoelectronic nanostructures and nanodevices. Chengyao Li is a PhD student, who is expected to get his degree in 2010.