Filtyp
Antimonide-based nanowires represent an important new class of material with great promise for both fundamental physics studies and various device applications. We report a comprehensive study on understanding the growth behaviour of GaxIn1-xSb nanowires on GaAs substrates using Au nanoparticles. First, the effect of growth parameters on the morphology and composition of GaxIn1-xSb nanowires is ex
To investigate whether messenger ribonucleic acid (mRNA) expression of TMPRSS2-ERG fusion gene, a suggested prostate cancer (PCa) biomarker, was specific to cancerous lesions alone and to study the expression of SPINK1 and PCA3 mRNAs in the same cohort to also explore the proposed mutual exclusivity of TMPRSS2-ERG and SPINK1 expression.
We have prepared GaAs wurtzite (WZ)-zinc blende (ZB) nanowire heterostructures by Au particle-assisted metal-organic vapor phase epitaxy (MOVPE) growth. Superior crystal quality of both the transition region between WZ and ZB and of the individual segments themselves was found for WZ-ZB single heterostructures. Pure crystal phases were achieved and the ZB segments were found to be free of any stac
The epitaxial growth of antimonide-based nanowires has become an attractive subject due to their interesting properties required for various applications such as long-wavelength IR detectors. The studies conducted on antimonide-based nanowires indicate that they preferentially crystallize in the zinc blende (ZB) crystal structure rather than wurtzite (WZ), which is common in other III-V nanowire m
We propose a model that explains the phenomenon of polytypism in metal particle-seeded III-V semiconductor nanowires. The model is based on classical nucleation theory, utilizing the axial next-nearest-neighbor Ising (ANNNI) model to account for interlayer interaction up to the third nearest-neighboring layer. We investigate the limits of polytypism by varying the ANNNI interaction parameters. The
The development of methods to produce nanoparticles with unique properties via the aerosol route is progressing rapidly. Typical characterization techniques extract particles from the synthesis process for subsequent offline analysis, which may alter the particle characteristics. In this work, we use laser-vaporization aerosol mass spectrometry (LV-AMS) with 70-eV electron ionization for real-time
The nanowire geometry offers significant advantages for exploiting the potential of III-Sb materials. Strain due to lattice mismatch is efficiently accommodated, and carrier confinement effects can be utilized in tunneling and quantum devices for which the III-Sb materials are of particular interest. It has however proven difficult to grow thin (below a few tens of nanometers), epitaxial III-Sb na
Thin InAs layers and membranes are fabricated on GaAs substrates using GaSb buffer layers grown by MOVPE. The quality of the GaSb buffer layers is optimized and epitaxial InAs layers are grown on GaSb layers of various thickness. The best GaSb buffer layers are obtained for a nucleation temperature of 450 degrees C and a subsequent growth temperature of 570 degrees C with a V/III ratio of 3, as co
Repeated injury of the airway epithelium caused by hyperpnoea of poorly conditioned air has been proposed as a key factor in the pathogenesis of exercise-induced bronchoconstriction (EIB) in athletes. In animals, the short-acting beta(2)-agonist terbutaline has been shown to reduce dry airflow-induced bronchoconstriction and the associated shedding of airway epithelial cells. Our aim was to test t
We report measured quantized conductance and quasi-ballistic transport in selectively regrown In0.85Ga0.15As nanowires. Very low parasitic resistances obtained by regrowth techniques allow us to probe the near-intrinsic electrical properties, and we observe several quantized conductance steps at 10 K. We extract a mean free path of 180 +/- 40 nm and an effective electron mobility of 3300 +/- 300 c
III-V Nanowires (NWs) grown with metal-organic chemical vapor deposition commonly show a polytypic crystal structure, allowing growth of structures not found in the bulk counterpart. In this paper we studied the radial overgrowth of pure wurtzite (WZ) GaAs nanowires and characterized the samples with high resolution X-ray diffraction (XRD) to reveal the crystal structure of the grown material. In
Semiconductor-oxide heterointerfaces have several electron volts high-charge carrier potential barriers, which may enable devices utilizing quantum confinement at room temperature. While a single heterointerface is easily formed by oxide deposition on a crystalline semiconductor, as in MOS transistors, the amorphous structure of most oxides inhibits epitaxy of a second semiconductor layer. Here, w
Axially defined GaInP single nanowire (NW) p-i-n junctions are demonstrated, with photocurrent response and yellow-green electroluminescence near the indirect bandgap crossover point at 2.18 eV (569 nm). We use DEZn and H2S as p- and n-type dopants, and find that they both affect the material composition and the crystal structure. The photovoltaic efficiency is comparable to single NW devices from
Some patients with chronic obstructive pulmonary disease (COPD) show increased airway inflammation and bacterial colonization during stable phase. The aim of this study was to follow COPD patients and investigate chronic colonization with pathogenic bacteria during stable disease phase, and relate these findings to clinical parameters, inflammatory pattern, lung function, and exacerbations.
We present temperature dependent electrical measurements on n-type InAs/InSb nanowire heterostructure field-effect transistors. The barrier height of the heterostructure junction is determined to be 220 meV, indicating a broken bandgap alignment. A clear asymmetry is observed when applying a bias to either the InAs or the InSb side of the junction. Impact ionization and band-to-band tunneling is m
The aim of this study was to investigate the microvascular responses in the skin, to local heat, iontophoretically administered acetylcholine and to sodium nitroprusside in relation to cardiovascular damage in patients with systemic lupus erythematosus (SLE) and matched controls. We also wanted to examine if the ongoing medication in SLE patients influenced this vascular response. We investigated
Focused ion beam is a powerful method for cross-sectional transmission electron microscope sample preparation due to being site specific and not limited to certain materials. It has, however, been difficult to apply to many nanostructured materials as they are prone to damage due to extending from the surface. Here we show methods for focused ion beam sample preparation for transmission electron m
Thymic stromal lymphopoietin (TSLP), an immunomodulating potentially disease-inducing cytokine, is overproduced in TLR3-stimulated bronchial epithelial cells from asthmatic donors whereas production of antiviral IFNβ is deficient. It is of therapeutic interest that capsazepine inhibits epithelial TSLP and relaxes human small airways with similar potencies. However, it is not known if other capsaze
The MHC (Major Histocompatibility Complex) plays an important role in the immune system of vertebrates. MHC genes are extremely polymorphic and this variation is considered to be maintained by selection from pathogens. We investigate whether MHC diversity (number of different alleles per individual) affects the survival and recruitment of nestling house sparrows. We hypothesize that individuals wi
