Localized degradation and breakdown study of cerium-oxide high-к gate dielectric material using scanning tunneling microscopy

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

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Roughness measurements of nonlinear optical polymer films by scanning tunneling microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100152082 ◽

1989 ◽

Vol 47 ◽

pp. 22-23

Author(s):

I. H. Musselman ◽

R.-T. Chen ◽

P. E. Russell

Keyword(s):

Surface Roughness ◽

Scanning Tunneling Microscopy ◽

Nonlinear Optical ◽

Polymer Surface ◽

Light Extinction ◽

Scanning Tunneling ◽

Silicon Substrates ◽

Tunneling Microscopy ◽

Optical Polymer ◽

Total Light

Scanning tunneling microscopy (STM) has been used to characterize the surface roughness of nonlinear optical (NLO) polymers. A review of STM of polymer surfaces is included in this volume. The NLO polymers are instrumental in the development of electrooptical waveguide devices, the most fundamental of which is the modulator. The most common modulator design is the Mach Zehnder interferometer, in which the input light is split into two legs and then recombined into a common output within the two dimensional waveguide. A π phase retardation, resulting in total light extinction at the output of the interferometer, can be achieved by changing the refractive index of one leg with respect to the other using the electrooptic effect. For best device performance, it is essential that the NLO polymer exhibit minimal surface roughness in order to reduce light scattering. Scanning tunneling microscopy, with its high lateral and vertical resolution, is capable of quantifying the NLO polymer surface roughness induced by processing. Results are presented below in which STM was used to measure the surface roughness of films produced by spin-coating NLO-active polymers onto silicon substrates.

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Practical applications of scanning tunneling microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100152069 ◽

1989 ◽

Vol 47 ◽

pp. 18-19

Author(s):

D. R. Denley

Keyword(s):

High Resolution ◽

Scanning Tunneling Microscopy ◽

Quantitative Information ◽

Digital Data ◽

Scanning Tunneling ◽

Ambient Atmosphere ◽

Tunneling Microscopy ◽

Clear Trend ◽

Practical Applications ◽

Promising Tool

Scanning tunneling microscopy (STM) has recently been introduced as a promising tool for analyzing surface atomic structure. We have used STM for its extremely high resolution (especially the direction normal to surfaces) and its ability for imaging in ambient atmosphere. We have examined surfaces of metals, semiconductors, and molecules deposited on these materials to achieve atomic resolution in favorable cases.When the high resolution capability is coupled with digital data acquisition, it is simple to get quantitative information on surface texture. This is illustrated for the measurement of surface roughness of evaporated gold films as a function of deposition temperature and annealing time in Figure 1. These results show a clear trend for which the roughness, as well as the experimental deviance of the roughness is found to be minimal for evaporation at 300°C. It is also possible to contrast different measures of roughness.

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