The method, which is based on near-field microscopy, opens new avenues for analyzing mechanical properties of high-performance materials or for contact-free mapping of local conductivity in strain-engineered electronic devices (Nature Nanotechnology, advanced online publication, 11 Jan. 2009).
Infrared visualization of nanocrack evolution. a) Topography of triangular indents (depressions) at the surface of a SiC crystal. Indentation was performed by pressing a sharp diamond tip into the crystal surface. With increasing force F, the depression becomes larger and deeper. b) The infrared near-field images recorded at about 10 µm wavelength clearly show the regions around the indent where the crystal lattice is compressed (bright) or stretched (dark). Because of the exceptional high spatial resolution, the images reveal the onset and formation of nanoscale cracks (marked by dashed blue circlse) when the indentation force is increased. Copyright: Andreas Huber, Max Planck Institute of Biochemistry, Martinsried
Visualizing strain at length scales below 100 nm is a key requirement in modern metrology because strain determines the mechanical and electrical properties of high-performance ceramics or modern electronic devices, respectively. The non-invasive mapping of strain with nanoscale spatial resolution, however, is still a challenge.
A promising route for highly sensitive and non-invasive mapping of nanoscale material properties is scattering-type Scanning Near-field Optical Microscopy (s-SNOM). Part of the team had pioneered this technique over the last decade, enabling chemical recognition of nanostructures and mapping of local conductivity in industrial semiconductor nanodevices. The technique makes use of extreme light concentration at the sharp tip of an Atomic Force Microscope (AFM), yielding nanoscale resolved images at visible, infrared and terahertz frequencies. The s-SNOM thus breaks the diffraction barrier throughout the electromagnetic spectrum and with its 20 nm resolving power matches the needs of modern nanoscience and technology.
Now, the research team has provided first experimental evidence that the microscopy technique is capable of mapping local strain and cracks of nanoscale dimensions. This was demonstrated by pressing a sharp diamond tip into the surface of a Silicon Carbide crystal. With the near-field microscope the researchers were able to visualize the nanoscopic strain field around the depression and the generation of nanocracks (see Figure). "Compared to other methods such as electron microscopy, our technique offers the advantage of non-invasive imaging without the need of special sample preparation" says Andreas Huber who performed the experiments within his Ph.D. project. "Specific applications of technological interest could be the detection of nanocracks before they reach critical dimensions, e.g. in ceramics or Micro-Electro-Mechanical Systems (MEMS), and the study of crack propagation", says Alexander Ziegler.
The researchers also demonstrated that s-SNOM offers the intriguing possibility of mapping free-carrier properties such as density and mobility in strained silicon. By controlled straining of silicon, the properties of the free carriers can be designed, which is essential to further shrink and speed-up future computer chips. For both development and quality control, the quantitative and reliable mapping of the carrier mobility is strongly demanded but hitherto no tool has been available. "Our results thus promise interesting applications of s-SNOM in semiconductor science and technology such as the quantitative analysis of the local carrier properties in strain-engineered electronic nanodevices" says Rainer Hillenbrand, leader of the Nano-Photonics Group at MPI and the Nanooptics Laboratory at nanoGUNE.Original publication:
Eva-Maria Diehl | Max-Planck-Gesellschaft
Further reports about: > Near-field Optical Microscopy > Semiconductor > Silicon Carbide crystal > electronic devices > high-performance ceramics > infrared light > nanocracks > nanoscale spatial resolution > nanoscale strain fields > near-field microscopy > plasma physics > strain-engineered electronic devices > terahertz frequencies
New approach to revolutionize the production of molecular hydrogen
22.05.2017 | Technische Universität Dresden
Photocatalyst makes hydrogen production 10 times more efficient
19.05.2017 | Kobe University
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
23.05.2017 | Event News
22.05.2017 | Event News
17.05.2017 | Event News
23.05.2017 | Earth Sciences
23.05.2017 | Life Sciences
23.05.2017 | Physics and Astronomy