MAT Seminar

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Coherent and incoherent TEM imaging method in application to
nano-materials Studies
Jin-Ping Zhang
Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences


Since the great achievement in development of electron source, a new method of
scanning transmission electron microscopy with a field-emission-gun could provide a
probe near 1 angstrom in diameter for both high resolution imaging and chemical
information collection of EDS or EELS spectrum simultaneously. The incoherent
imaging method has been widely used to studies of determine nano-material or
interface structures in distinguish of different atomic columns, since the image can be
directly interpreted with the arrangement of different species, the image contrast is
sensitive to the atomic number of projected columns, called as ‘Z-contrast’. In
combine STEM with any other conventional TEM methods, we are able to obtain the
full length of structural information.
Here we present the works on (1) identification of the core-shell structure of
Au/Pd catalyst particles; (2) the interface reconstruction of LaAlO3 on Si; (3) the
interface surrounded ErAs quantum dots in GaAs; (4) the In distribution in InGaAS
quantum posts, and (5) a new growth mechanism of Nano-materials (TiO2 rutile
nanowire growth), as examples to discuss the different ways in TEM studies.
A discussion of nanowire growth: a wetting layer of Ni-P alloy can work as catalyst, as a function
of a melted particle in a vapor-liquid-solid growth.