| 1. |
- Bruhn, Benjamin, et al.
(författare)
-
Controlled fabrication of individual silicon quantum rods yielding high intensity, polarized light emission
- 2009
-
Ingår i: Nanotechnology. - : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 20:50, s. 1-5
-
Tidskriftsartikel (refereegranskat)abstract
- Elongated silicon quantum dots (also referred to as rods) were fabricated using a lithographic process which reliably yields sufficient numbers of emitters. These quantum rods are perfectly aligned and the vast majority are spatially separated well enough to enable single-dot spectroscopy. Not only do they exhibit extraordinarily high linear polarization with respect to both absorption and emission, but the silicon rods also appear to luminesce much more brightly than their spherical counterparts. Significantly increased quantum efficiency and almost unity degree of linear polarization render these quantum rods perfect candidates for numerous applications.
|
|
| 2. |
- Sychugov, Ilya, et al.
(författare)
-
Manifold Enhancement of Electron Beam Induced Deposition Rate at Grazing Incidence
- 2010
-
Ingår i: Nanotechnology. - : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 21:2, s. 025303-
-
Tidskriftsartikel (refereegranskat)abstract
- It is shown how a significant drawback of the electron beam induced deposition technique, namely its low deposition rate, can be circumvented. By tilting a sample, a larger part of the primary electron beam energy becomes dissipated closer to the interface. This in turn increases the emission of secondary electrons, largely responsible for the deposition of the adsorbed molecule components on the surface. An order of magnitude increase in the deposition rate is reported in the fabrication of metal nanowires from organic precursor gas.
|
|
| 3. |
- Sychugov, Ilya, et al.
(författare)
-
Optical and Electrical Characterization at the Nanoscale by a Transparent Tip of a Scanning Tunneling Microscope
- 2009
-
Ingår i: Nanotechnology. - : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 20:14, s. 145706-
-
Tidskriftsartikel (refereegranskat)abstract
- A new type of scanning probe microscope, combining features of the scanning tunnelling microscope, the scanning tunnelling luminescence microscope with a transparent probe and the aperture scanning near-field optical microscope, is described. Proof-of-concept experiments were performed under ultrahigh vacuum conditions at varying temperature on GaAs/AlAs heterostructures.
|
|
| 4. |
- Sychugov, Ilya, et al.
(författare)
-
Sub-10 nm crystalline silicon nanostructures by electron beam induced deposition lithography
- 2010
-
Ingår i: Nanotechnology. - : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 21:28, s. 285307-
-
Tidskriftsartikel (refereegranskat)abstract
- A novel top-down approach for the controllable fabrication of semiconductor nanostructures exhibiting quantum effects is described. By decomposing metal-rich precursor gas molecules with an electron beam, a sub-10 nm metal pattern can be formed and subsequently transferred to a semiconductor substrate. In such a way monocrystalline silicon nanodots and nanowires are produced as revealed by transmission electron microscopy. It is also shown how through controlled thermal or chemical oxidation the nanostructure surface can be passivated. By providing direct access to the sub-10 nm size range this method possesses promising potential for application in the quantum dot and nanoelectronics fields.
|
|
| 5. |
- Zhang, Miao, et al.
(författare)
-
Oxidation of nanopores in a silicon membrane : self-limiting formation of sub-10nm circular openings
- 2014
-
Ingår i: Nanotechnology. - : Institute of Physics (IOP). - 0957-4484 .- 1361-6528. ; 25:35, s. 355302-
-
Tidskriftsartikel (refereegranskat)abstract
- We describe a simple but reliable approach to shrink silicon nanopores with nanometer precision for potential high throughput biomolecular sensing and parallel DNA sequencing. Here, nanopore arrays on silicon membranes were fabricated by a self-limiting shrinkage of inverted pyramidal pores using dry thermal oxidation at 850 degrees C. The shrinkage rate of the pores with various initial sizes saturated after 4 h of oxidation. In the saturation regime, the shrinkage rate is within +/- 2 nm h(-1). Oxidized pores with an average diameter of 32 nm were obtained with perfect circular shape. By careful design of the initial pore size, nanopores with diameters as small as 8 nm have been observed. Statistics of the pore width show that the shrinkage process did not broaden the pore size distribution; in most cases the distribution even decreased slightly. The progression of the oxidation and the deformation of the oxide around the pores were characterized by focused ion beam and electron microscopy. Cross-sectional imaging of the pores suggests that the initial inverted pyramidal geometry is most likely the determining factor for the self-limiting shrinkage.
|
|
| 6. |
- Chen, Si, 1985, et al.
(författare)
-
Ultrahigh sensitivity made simple : nanoplasmonic label-free biosensing with an extremely low limit-of-detection for bacterial and cancer diagnostics.
- 2009
-
Ingår i: Nanotechnology. - : Institute of Physics (IOP). - 0957-4484 .- 1361-6528. ; 20:43
-
Tidskriftsartikel (refereegranskat)abstract
- We present a simple and robust scheme for biosensing with an ultralow limit-of-detection down to several pg cm(-2) (or several tens of attomoles cm(-2)) based on optical label-free biodetection with localized surface plasmon resonances. The scheme utilizes cost-effective optical components and comprises a white light source, a properly functionalized sensor surface enclosed in a simple fluidics chip, and a spectral analyzer. The sensor surface is produced by a bottom-up nanofabrication technique with hole mask colloidal lithography. Despite its simplicity, the method is able to reliably detect protein-protein binding events at low picomolar and femtomolar concentrations, which is exemplified by the label-free detection of the extracellular adherence protein (EAP) found on the outer surface of the bacterium Staphylococcus aureus and of prostate-specific antigen (PSA), which is believed to be a prostate cancer marker. These experiments pave the way towards an ultra-sensitive yet compact biodetection platform for point-of-care diagnostics applications.
|
|
| 7. |
- Gowtham, S., et al.
(författare)
-
First-principles study of physisorption of nucleic acid bases on small-diameter carbon nanotubes
- 2008
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 19:12, s. 125701-
-
Tidskriftsartikel (refereegranskat)abstract
- We report the results of our first-principles study based on density functional theory on the interaction of the nucleic acid base molecules adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U), with a single-walled carbon nanotube (CNT). Specifically, the focus is on the physisorption of base molecules on the outer wall of a (5, 0) metallic CNT possessing one of the smallest diameters possible. Compared to the case for CNTs with large diameters, the physisorption energy is found to be reduced in the high-curvature case. The base molecules exhibit significantly different interaction strengths and the calculated binding energies follow the hierarchy G>A>T>C>U, which appears to be independent of the tube curvature. The stabilizing factor in the interaction between the base molecule and CNT is dominated by the molecular polarizability that allows a weakly attractive dispersion force to be induced between them. The present study provides an improved understanding of the role of the base sequence in deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) in their interactions with carbon nanotubes of varying diameters.
|
|
| 8. |
- Mikkelsen, Anders, et al.
(författare)
-
The influence of lysine on InP(001) surface ordering and nanowire growth
- 2005
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 16:10, s. 2354-2359
-
Tidskriftsartikel (refereegranskat)abstract
- We report on high resolution photoelectron core level spectroscopy (HRCLS) and scanning tunnelling microscopy (STM) measurements of the decomposition of lysine adsorbed on InP(001) substrates. We find that components from the lysine can be present on the InP surface even after annealing to 600 degrees C and desorption of the native surface oxide. We further observe that while a crystalline surface phase can be observed on the epi-ready surface after annealing, the lysine treated surface still appears rough. We conclude that lysine residues inhibit the formation of a flat crystalline structure on the InP(001) surface. These results are discussed in terms of the lysine promotion of [001] nanowire growth.
|
|
| 9. |
- Kandemir, Ayse Cagil, et al.
(författare)
-
Polymer nanocomposite patterning by dip-pen nanolithography
- 2016
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 27:13
-
Tidskriftsartikel (refereegranskat)abstract
- The ultimate aim of this study is to construct polymer nanocomposite patterns by dip-pen nanolithography (DPN). Recent investigations have revealed the effect of the amount of ink (Laplace pressure) on the mechanism of liquid ink writing. In this study it is shown that not only the amount of ink, but also physisorption and surface diffusion are relevant. After a few writing steps, physisorption and surface diffusion outweigh the influence of the amount of ink, allowing consistent patterning governed by dwell times and writing speeds. Polymer matrices can be utilized as a delivery medium to deposit functional particles. DPN patterning of polymer nanocomposites allows for local tuning of the functionality and mechanical strength of the written patterns in high resolution, with the benefit of pattern flexibility. Typically polymer matrices with volatile components are used as a delivery medium for nanoparticle deposition, with subsequent removal of loosely bound matrix material by heating or oxygen plasma. In our study, nanocomposite patterns were constructed, and the differences between polymer and nanocomposite patterning were investigated. Cross-sectional SEM and TEM analysis confirmed that nanoparticles can be deposited with the liquid-polymer ink and are evenly distributed in the polymer matrix.
|
|
| 10. |
- Benedict, S., et al.
(författare)
-
Colloidal lithography nanostructured Pd/PdOx core-shell sensor for ppb level H2S
- 2018
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 29:25
-
Tidskriftsartikel (refereegranskat)abstract
- In this work we report on plasma oxidation of palladium (Pd) to form reliable palladium/palladium oxide (Pd/PdOx) core-shell sensor for ppb level H2S detection and its performance improvement through nanostructuring using hole-mask colloidal lithography (HCL). The plasma oxidation parameters and the sensor operating conditions are optimized to arrive at a sensor device with high sensitivity and repeatable response for H2S. The plasma oxidized palladium/palladium oxide sensor shows a response of 43.1% at 3 ppm H2S at the optimum operating temperature of 200 degrees C with response and recovery times of 24 s and 155 s, respectively. The limit of detection (LoD) of the plasma oxidised beam is 10 ppb. We further integrate HCL, a bottom-up and cost-effective process, to create nanodiscs of fixed diameter of 100 nm and varying heights (10, 15 and 20 nm) on 10 nm thin Pd beam which is subsequently plasma oxidized to improve the H2S sensing characteristics. The nanostructured Pd/PdOx sensor with nanodiscs of 100 nm diameter and 10 nm height shows an enhancement in sensing performance by 11.8% at same operating temperature and gas concentration. This nanostructured sensor also shows faster response and recovery times (15s and 100s, respectively) compared to the unstructured Pd/PdOx counterpart together with an experimental LoD of 10 ppb and the estimated limit going all the way down to 2 ppb. Material characterization of the fabricated Pd/PdOx sensors is done using UV-vis spectroscopy and x-ray photoemission spectroscopy.
|
|
