In-Situ Electron Microscopy Testing of 1-D Nanostructures

Author(s):  
Horacio D. Espinosa

Over the past decade, there has been a substantial thrust to reduce the size of electronic and electromechanical systems to the nano scale by fabricating devices out of thin films, carbon nanotubes (CNTs) and nanowires (NWs). In these applications, a thorough understanding of material mechanical, electrical and thermal properties as well as device performance and reliability requires the development of novel experimental approaches. In this presentation the design, microfabrication and operation of a MEMS based nanoscale material testing system (n-MTS, see Fig. 1) will be presented. Results obtained from in-situ SEM and TEM tensile testing of NWs and CNTs will be discussed. We will show that TEM imaging is required to properly assess the modulus and strength of multi-walled CNTs (MWCNTs) and demonstrate that the assumption of outer shell failure is not accurate in most cases. We will also discuss a change in failure mode as a function of electron and ion radiation.

2018 ◽  
Vol 149 ◽  
pp. 452-458 ◽  
Author(s):  
Rajaprakash Ramachandramoorthy ◽  
Allison Beese ◽  
Horacio Espinosa

Author(s):  
R. Dale Moorhead ◽  
Helmut Poppa

The electron microscope has often been used in the past to study in-situ the details of thin film nucleation and growth processes. However, a lack of adequate control of important experimental deposition parameters, such as substrate cleanliness, residual gas pressure and composition, and super-saturation ratio, has limited the usefulness of the technique and in most cases prevented the acquisition of reliable quantitative results.Accordingly, a new specimen chamber for use on a RCA EMU-4 instrument was built that regularly reaches base pressures of 3x10-10 torr, maintains pressures of less than 5x10-9 torr during the vapor deposition phase, and affords accurate control of the other deposition parameters.


Sensors ◽  
2017 ◽  
Vol 17 (8) ◽  
pp. 1800 ◽  
Author(s):  
Xuan Ye ◽  
Zhiguo Cui ◽  
Huajun Fang ◽  
Xide Li

Author(s):  
R. E. Herfert

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.


Author(s):  
J. S. Maa ◽  
Thos. E. Hutchinson

The growth of Ag films deposited on various substrate materials such as MoS2, mica, graphite, and MgO has been investigated extensively using the in situ electron microscopy technique. The three stages of film growth, namely, the nucleation, growth of islands followed by liquid-like coalescence have been observed in both the vacuum vapor deposited and ion beam sputtered thin films. The mechanisms of nucleation and growth of silver films formed by ion beam sputtering on the (111) plane of silicon comprise the subject of this paper. A novel mode of epitaxial growth is observed to that seen previously.The experimental arrangement for the present study is the same as previous experiments, and the preparation procedure for obtaining thin silicon substrate is presented in a separate paper.


Author(s):  
Jerrold L. Abraham

Inorganic particulate material of diverse types is present in the ambient and occupational environment, and exposure to such materials is a well recognized cause of some lung disease. To investigate the interaction of inhaled inorganic particulates with the lung it is necessary to obtain quantitative information on the particulate burden of lung tissue in a wide variety of situations. The vast majority of diagnostic and experimental tissue samples (biopsies and autopsies) are fixed with formaldehyde solutions, dehydrated with organic solvents and embedded in paraffin wax. Over the past 16 years, I have attempted to obtain maximal analytical use of such tissue with minimal preparative steps. Unique diagnostic and research data result from both qualitative and quantitative analyses of sections. Most of the data has been related to inhaled inorganic particulates in lungs, but the basic methods are applicable to any tissues. The preparations are primarily designed for SEM use, but they are stable for storage and transport to other laboratories and several other instruments (e.g., for SIMS techniques).


Author(s):  
Z. Liliental-Weber ◽  
C. Nelson ◽  
R. Ludeke ◽  
R. Gronsky ◽  
J. Washburn

The properties of metal/semiconductor interfaces have received considerable attention over the past few years, and the Al/GaAs system is of special interest because of its potential use in high-speed logic integrated optics, and microwave applications. For such materials a detailed knowledge of the geometric and electronic structure of the interface is fundamental to an understanding of the electrical properties of the contact. It is well known that the properties of Schottky contacts are established within a few atomic layers of the deposited metal. Therefore surface contamination can play a significant role. A method for fabricating contamination-free interfaces is absolutely necessary for reproducible properties, and molecularbeam epitaxy (MBE) offers such advantages for in-situ metal deposition under UHV conditions


Author(s):  
F. M. Ross ◽  
R. Hull ◽  
D. Bahnck ◽  
J. C. Bean ◽  
L. J. Peticolas ◽  
...  

We describe an investigation of the electrical properties of interfacial dislocations in strained layer heterostructures. We have been measuring both the structural and electrical characteristics of strained layer p-n junction diodes simultaneously in a transmission electron microscope, enabling us to correlate changes in the electrical characteristics of a device with the formation of dislocations.The presence of dislocations within an electronic device is known to degrade the device performance. This degradation is of increasing significance in the design and processing of novel strained layer devices which may require layer thicknesses above the critical thickness (hc), where it is energetically favourable for the layers to relax by the formation of misfit dislocations at the strained interfaces. In order to quantify how device performance is affected when relaxation occurs we have therefore been investigating the electrical properties of dislocations at the p-n junction in Si/GeSi diodes.


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