Images 2014

Best image:

Image by Apurba Dev, KTH/ICT/MF

Blooming Nanowires: This is an SEM image of ZnO nanowire grown on zink foil using hydrothermal technique. The diameters of the nanowires are in the range of 20-80 nm and several microns long. The image was selectively colorized using GIMP. The blue parts of the image are deposition of some large crystals on the nanowire film.  original image (jpg 354 kB)

Honorable mentions:

Jin Dai, KTH/ICT/MNF/OFO

Nanomoon: The SEM image shows the gold nanoparticles of a plasmonic light absorber which can be potentially used for light harvesting. The sample was fabricated using Electron-beam lithography. The shapes of the gold nanoparticles are similar as different lunar phases, from an artistic crescent to a full moon, but at the nanometer scale. original image (jpg 166 kB)

Bikash Choudhury and Inese Krasovska, KTH/ICT/MNF/HMA

Don't cut the trees, cut down Carbon dioxide - Stumbled Si nanopillar: A scanning electron microscope (SEM) image of Silicon (Si) nanopillars. Plasma assisted dry etching processes are used to fabricate the Si nanopillars. Some part of the image is recolored to match the text content. It shows that some pillars are fallen down during sample handling. The picture resembles tree logs. Trees are the main consumer of CO2, the greenhouse gas and keep good balance in Environment. There has been major concern on deforestation and also high use of non-renewable energy resources, leading to increase in greenhouse gases, like CO2 and global warming. In this regard reforestation and use of green energy, like solar photovoltaic (PV) energy are priority issues in present day scenarios. In fact Si nanopillars (basically the upright ones) are highly talked for high efficiency solar PV cells due to their adapted optical and electrical properties. These upright pillars can maximize the use of solar photons and can be good candidate for cheaper and greener energy source to protect Environment. So here is our  ‘mantra’ for environmental cause- ‘‘think twice before cutting down the trees and handle the Silicon nanopillar samples with care’’.  original image (jpg 130 kB)

Michael Fokine & Ursula Gibson, KTH/SCI/APHYS/Laserfysik

Silicon microspheres in silica microsphere: CO2 laser heating of a silica-cladded silicon-core fiber (125 µm diameter) resulting in microsphere formation due to Plateau-Rayleigh capillary instability. original image (jpg 212 kB)

Federico Pevere, KTH/ICT/MNF/MF

Swedish nanowall: AFM image of silicon nano-walls in a honeycomb-like structure used as a reference to localize silicon nanocrystals for single-dot spectroscopy. Probably some of the nano-walls have been almost completely etched away during the fabrication process, leaving just a few nanometers of silicon that can be barely noticed from the AFM images. Acknowledgements: Dr. Benjamin Bruhn for the sample fabrication and Dr. Torsten Schmidt for the technical support. original image (png 335 kB)

Reza Sanatinia, KTH/ICT/MNF/HMA

Royal Azure at Nanoscale: Description: Second-harmonic generation (SHG) light from KTH logo, consists of individual GaP nanopillars with diameters of ~ 250 nm. The presented KTH logo is patterned with e-beam lithography and dry etching on (100) GaP substrate. Second- harmonic light is only radiated from GaP nanopillars. The image is recorded by a CCD camera in the far-field and the SHG wavelength is 415 nm. A Ti: Sapphire pump laser with 100 fs pulses and a central wavelength of 830 nm at 82 MHz repetition rate was used. original image (jpg 620 kB)

Aleksandrs Marinins, KTH/ICT/MNF/OFO

Quantun-dot ADOPT: The presented image is a digitally post-manipulated (Photoshop) TEM micrograph of CdSe quantum dots coated with SiO2. I chemically synthesized these nanocomposites during my Master thesis in Functional Nano Materials group. Quantum dots are semiconductor nanocrystals with excellent optical properties, their emission wavelength strongly depends on particle size, making quantum dots extremely valuable tool for biomedical imaging. I am not good enough in manipulating single nanoparticles, so I used Adobe Photoshop to align nanoparticles into ADOPT logo. There are silica coated quantum dots of 2 sizes (30 and 20 nm) and few uncoated nanocrystals of 8 nm.  original image (JPG 368 kB)

Miao Zhang, KTH/ICT/MNF/MF

Happy Halloween!: "You know you have worked too hard when your sample stares back at you…" Electron beam lithography followed by plasma etching is a widely used technique to fabricate photonics devices. Here we show a dose test sample for a new e-beam positive resist SML300. The porous green layer is the resist layer. The orange “pumpkin” is the SiO2 layer on a silicon substrate. After e-beam lithography, the sample was etched by plasma etching to transfer the pattern into the oxide layer. Because of the porosity of the resist and the low exposure dose, only part of the pattern was transferred into the oxide layer, which somehow formed a screaming face. Once we have the nano-pumpkin, the next step is to put a candle inside… The image was taken using the Zeiss Gemini scanning-electron microscope in KTH’s Electrum lab in Kista. Image Colorizing was processed with software Paint shop. original image (jpg 350 kB)

Charlotte Liljestrand, KTH/SCI/APHYS/Laserfysik

The world’s smallest dancer?: During the investigation of the quality of this sub-μm photoresist pattern in the scanning electron microscope ‘SEM’ a dust particle got caught in the images by accident. The image shows the cross section of a 730 nm photo resist grating, from our in-house built laser interference lithographic system. During inspection of the images it was found that a dust particle had gotten caught and had taken the shape of a small dancer. To enhance her, this small dust dancer has been colored in during the post manipulation of the image. original image (jpg 159 kB)

Xi Chen & Yanting Sun, KTH/ICT/MNF/OFO&HMA

Bright field optical microscopic image of InP photonic crystal: The sample shown in the image is a InP material with sub-micro periodic structure on the surface. The periodic structure, also known as photonic crystal (PhC) structure is densely packed spherical voids etched in InP sample. These densely packed voids are defined by dispersing colloidal-form silica microspheres on substrate, material growth and etching of silica. The number of the dispersed layers of the microsphere is non-uniform within the image area. Such a non-uniformity of the PhC may results in various light scattering properties of the PhC with different number of layers. This may explain the distinct and bright colors in each subdomains of the sample surface. The subdomains are easily distinguished by their strong color contrast, with typical size of tens of micrometer. The actual size of the image width is around 0.5 mm. The image is taken from a bright field optical microscope setup, with objective lens of magnification of 20. The color saturation and exposure of the image is modified to enhance the visual experience.  original image (jpg 502 kB)

Xi Chen, KTH/ICT/MNF/OFO

Silicon disk resonator optically tuned by an IR beam: The sample shown in the image is an array of microdisk resonators coupled to strip waveguides, fabricated from a silicon-on-insulator (SOI) wafer. The pink-color hat on top of the silicon disk is an IR light absorber with metal-insulator-metal (MIM) structure, which is efficient for absorbing IR light at wavelength of 1064 nm. The dark rods vertically symmetric to each other are the bare fiber tip (on the top) and its mirror image (at the bottom). A laser beam is incident from the fiber tip on the SOI device, shown as an extremely bright spot, even viewed by a silicon image device (designed as a visible image device, rather than an infrared image device). When the laser spot is aligned right onto the microdisk, the refractive index of the disk can be easily tuned by nonlinear optical effect, e.g. photothermal effect. The tuned disk will show a wavelength-shifted optical resonant spectrum, which can be measured by horizontally probing the disk with light from one strip waveguide end and collecting the transmitted light at the other waveguide end. As the image is taken from an oblique microscope setup, the optical axis of the microscope has a titled angle of 45 deg with respect to the sample surface normal direction. Therefore, the adjacent disks and strip waveguides are quite out-of-focus, as well as the fiber tip and its mirror image. The objective lens of the microscope has a magnification of 20. The illumination light is applied from the side onto the sample, not from the microscope column. The image is in JPG format with a pixel dimension of 2032*1514. The actual size of the image width is 0.5 mm. original image (jpg 950 kB)

Giriprasanth Omanakuttan, KTH/ICT/MNF/HMA

Smartphone Screen: A smart phone screen of OLED type has three subpixels with red, green and blue colors to create each color pixel. Each subpixel is basically a light-emitting diode made of organic material. By controlling of voltage applied, the intensity of emitted light from each subpixel can have 256 levels. Combining the subpixels produces a possible palette of 16.8 million colors (256 shades of red x 256 shades of green x 256 shades of blue). Here, the Galaxy s2 has Screen resolution of 480x800. If we multiply 480 columns by 800 rows by 3 subpixels, we get 1,152,000 LEDs on a glass substrate! The blue subpixels are bigger in size probably due to the fact that human eyes are less sensitive to blue light. Images taken with the microscope in Electrum cleanroom. original image (jpg 58 kB)

Inese Krasovska, KTH/ICT/MNF/HMA

Micro-heart: A scanning electron microscope (SEM) image of a hanging micro-ribbon folded into a heart-shaped structure. The image was taken while doing SEM imaging of GaAs nanowires, which were dispersed on a Si substrate. The GaAs nanowires were typically 450 nm in diameter and 18 µm long. While the dispersed GaAs nanowires showed good photoluminescence, the heart contour did not show any measurable optical activity suggesting that this is not composed of clusters of nanowires. The heart-shaped structures, as well as GaAs nanowires are recolored for an artistic purpose. Other features of the image are left unchanged. The image shows that it is important to notice small details while observing a thing. One must notice the details and be aware of the "observer effect"! original image (jpg 71 kB)

Lech Wosinski, KTH/ICT/MNF/FMI

Polymer cracks: Thin polymer layer spin-coated on a silicon wafer. Polymer cracked due to strain. Interesting is that all the cracks meet at right angle, see inset for details (pictures taken with optical microscope). This is due to the fact that a crack propagates in the direction which most efficiently relieves the stress. Since the stress near a given crack is parallel to its surface, other cracks tend to approach and meet it at right angles, this leads to a connected network pattern [1].
[1] Mady Elbahri, PhD thesis "Unconvent ional Nanomanufacturing on a Substrate", Technischen Fakultät der Christian- Albrechts- Universität zu Kiel (2007) d-nb.info/1019629770/34. original image (png 1.3 MB)

Min Yan, KTH/ICT/MNF/OFO

Homage to optical fiber: The image illustrates the fundamental mode propagating in an optical fiber. Optical fiber demonstrates the ultimate power of light (in the author’s opinion). Optical fiber has tremendous bandwidth for transmitting information over a long distance. It serves and will continue to serve as the core of our information society. The fiber shown has a core diameter of 9 micrometers.The vector fields (arrows) are calculated using a light wavelength of 1.55 micrometers, at which the clad (pure silica) has an index of 1.444 and the core has an index of 1.45. Effective mode index is 1.4472. Red and blue arrows represent electric and magnetic fields, respectively. Cladding shown has a diameter of 20 micrometers (real ones have 125 micrometers as a standard). The cutaway has a length corresponding to one light wavelength in the fiber (1.55/1.4472 or ~1.1 micrometers). For illustration purpose, the cutaway length is stretched out by 10 times. The red beam is an artist’s impression of power flow in the fiber. In the background there sits the earth taken care of by optical fibers. Tools used: Matlab, Povray. original image (png 820 kB)

Page responsible:Max Yan
Belongs to: School of Engineering Sciences (SCI)
Last changed: Apr 10, 2015