We use ultra-resolving terahertz (THz) near-field microscopy based on THz scattering at atomic force microscope tips to analyze 65-nm technology node transistors. Nanoscale resolution is achieved by ...THz field confinement at the very tip apex to within 30 nm. Images of semiconductor transistors provide evidence of 40 nm (λ/3000) spatial resolution at 2.54 THz (wavelength λ = 118μm) and demonstrate the simultaneous THz recognition of materials and mobile carriers in a single nanodevice. The mobile carrier contrast can be clearly related to near-field excitation of THz-plasmons in the semiconductor regions. The extraordinary high sensitivity of our microscope provides THz near-field contrasts from less than 100 mobile electrons in the probed volume.
Long-Wave-Infrared Near-Field Microscopy Keilmann, F.; Knoll, B.; Kramer, A.
physica status solidi (b),
September 1999, Letnik:
215, Številka:
1
Journal Article
Recenzirano
We have extended scanning near‐field optical microscopy to work at long wavelengths with sub‐μm resolution. This allows to exploit the rich spectroscopic signatures of vibrations and other low‐energy ...excitations for nano‐scale imaging. The experiment uses an “apertureless” metal probe tip which at the same time serves as force and tunneling probe tip to acquire the surface topography. The applied microwave or infrared wave generates an enhanced longitudinal field at the tip apex. The tip scattering is recorded with a resolution of about 100 nm, a limit given by the tip diameter. Surface‐enhanced infrared absorption contrast is observed as predicted by a model which treats the combined scattering of the tip dipole together with its mirror dipole in the sample.
By scanning a metal grid sample between two coaxial transmission line tips, we resolve
Δx ≈ 10
μm features using up to
λ = 20 m wavelengths, achieving wavelength-relative resolution
Δx
λ
< 5 × 10
−7
...in both magnitude and phase. As an example of the technique's quite general application to conductivity-contrast microscopy, we measure the local transmittance of a
GaAs
AlGaAs
heterostructure versus magnetic field. We view this work as a proof-of-principle experiment which justifies scaling down the coaxial tip geometry to the sub-micrometer regime.
A novel scanning-probe setup is reported that maps the complex transmission of microwaves. Response to topographic features as small as 15 nm was observed. The sharpened coaxial probe tip serves as a ...microwave antenna and, at the same time, as a tunnel tip to warrant precise distance control by STM (scanning tunneling microscope) feedback. The instrument can be applied to map the microwave conductivity of, e.g. thin films or low-dimensional semiconductors. Consequences for the development of an infrared microscope are outlined.
van der Waals heterostructures assembled from atomically thin crystalline layers of diverse two-dimensional solids are emerging as a new paradigm in the physics of materials. We used infrared ...nanoimaging to study the properties of surface phonon polaritons in a representative van der Waals crystal, hexagonal boron nitride. We launched, detected, and imaged the polaritonic waves in real space and altered their wavelength by varying the number of crystal layers in our specimens. The measured dispersion of polaritonic waves was shown to be governed by the crystal thickness according to a scaling law that persists down to a few atomic layers. Our results are likely to hold true in other polar van der Waals crystals and may lead to new functionalities.
Microwaves near 42 GHz are found to influence the growth of Saccharomyces cerevisiae. The growth is measured photometrically in stirred aqueous culture. The microwave effect occurs and saturates ...above a threshold intensity much less than 10 mW/sq cm, excluding any explanation based on microwave heating. A surprisingly strong frequency dependence is observed, with resonances as narrow as 8 MHz. These results confirm the existence of a nonthermal resonant microwave sensitivity in biology; they suggest yet unknown tuned systems triggering yet unknown biological actions.
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