Effects of annealing regims on the structural and optical properties of inas and gasb nanocryctals created by ion-beam synthesis in Si matrix

We have studied the ion-beam synthesis of InAs and GaSb nanocrystals in Si by high-fluence implantation of (As+In) and (Ga+Sb) ions followed a thermal annealing. In order to characterize the implanted samples Rutherford backscattering spectrometry in combination with the channelling (RBS/C), transmission electron microscopy (TEM), Raman spectrometry (RS) and low-temperature photoluminescence (PL) techniques were employed. It was demonstrated that by introducing getter, varying the ion implantation temperature, ion fluences and post-implantation annealing duration and temperature it is possible to form InAs and GaSb nanocrystals in the range of sizes of (2 – 80) nm and create different types of secondary defects distribution. RS results confirm the crystalline state of the clusters in the silicon matrix after high-fluence implantation of heavy (As+In) and (Ga+Sb) ions. Significant redistribution of implanted species has been revealed after “hot” implantation and post-implantation annealing. We have suggested that it is caused by non-equilibrium diffusion. A broad band in the spectral region of 0.7 – 1.1 eV is detected in the photoluminescence spectra of the samples. The nature of this PL band is discussed.We have studied the ion-beam synthesis of InAs and GaSb nanocrystals in Si by high-fluence implantation of (As+In) and (Ga+Sb) ions followed a thermal annealing. In order to characterize the implanted samples Rutherford backscattering spectrometry in combination with the channelling (RBS/C), transmission electron microscopy (TEM), Raman spectrometry (RS) and low-temperature photoluminescence (PL) techniques were employed. It was demonstrated that by introducing getter, varying the ion implantation temperature, ion fluences and post-implantation annealing duration and temperature it is possible to form InAs and GaSb nanocrystals in the range of sizes of (2 – 80) nm and create different types of secondary defects distribution. RS results confirm the crystalline state of the clusters in the silicon matrix after high-fluence implantation of heavy (As+In) and (Ga+Sb) ions. Significant redistribution of implanted species has been revealed after “hot” implantation and post-implantation annealing. We have suggested that it is caused by non-equilibrium diffusion. A broad band in the spectral region of 0.7 – 1.1 eV is detected in the photoluminescence spectra of the samples. The nature of this PL band is discussed. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2083

Booster cavity and fundamental power coupler design issues for bERLinPro

HZB has started building the 50 MeV, 100mA demonstrator energy recovery linac ERL facility bERLinPro. The high power injector system needs to deliver this beam at 6.5 MeV by combining the energy gain of a 1.4 cell SRF photo injector and three Cornell style 2 cell booster cavities. One booster cavity will be operated at zero crossing for bunch energy chirping. Thus two booster cavities have to deliver 2MV each requiring a strong coupling with a loaded Q of 105. To house the two envisaged KEK fundamental power couplers FPC with the cavity, the geometry was slightly modified. Further, to increase coupling and reduce transverse kick effects to the beam, a golf tee antenna tip was designed. This paper summarizes the SRF challenges for the booster cavities, the operational conditions and the modification to the KEK couplers, including tracking calculations to estimate the coupler kick effect to higher orde

Structure and optical properties of silicon layers with GaSb nanocrystals created by ion-beam synthesis

We have studied the ion-beam synthesis of GaSb nanocrystals in Si by high-fluence implantation of Sb and Ga ions followed by thermal annealing. RBS, TEM/TED, RS, and photoluminescence (PL) were employed to characterize the implanted layers. It was found that the nanocrystals size increases from 5 to 60 nm in the samples annealed at 900 8Cup to 20–90 nm in the samples annealed at 1100 8C. An existence of significant mechanical stresses within implanted layers has been detected. The stress values have been calculated from the shift of the Si first order Raman band. For the samples annealed at 900 8C a broad band in the spectral region of about 0.75–1.05 eV is detected in the PL spectra. The nature of this PL band is discussed

Structure and Optical Properties of Silicon Layers with GaSb Nanocrystals Created by Ion-Beam Synthesis

We have studied the ion-beam synthesis of GaSb nanocrystals in Si by high-fluence “hot” implantation of Sb and Ga ions followed by thermal annealing. The Rutherford backscattering, transmission electron microscopy/ transmission electron di˙raction, Raman spectroscopy and photoluminescence were used to characterize the implanted layers. It was found that the nanocrystal size increases from 5 to 60 nm in the samples annealed at 900 ±C up to 20–90 nm in those annealed at 1100 ±C. For the samples annealed at 900 ±C a broad band in the region of 0.75–1.05 eV is registered in the photoluminescence spectra. The nature of this photoluminescence band is discussed

Anti-CD3 Fab Fragments Enhance Tumor Killing by Human γδ T Cells Independent of Nck Recruitment to the γδ T Cell Antigen Receptor

T lymphocytes expressing the γδ T cell receptor (γδ TCR) can recognize antigens expressed by tumor cells and subsequently kill these cells. γδ T cells are indeed used in cancer immunotherapy clinical trials. The anti-CD3ε antibody UCHT1 enhanced the in vitro tumor killing activity of human γδ T cells by an unknown molecular mechanism. Here, we demonstrate that Fab fragments of UCHT1, which only bind monovalently to the γδ TCR, also enhanced tumor killing by expanded human Vγ9Vδ2 γδ T cells or pan-γδ T cells of the peripheral blood. The Fab fragments induced Nck recruitment to the γδ TCR, suggesting that they stabilized the γδ TCR in an active CD3ε conformation. However, blocking the Nck-CD3ε interaction in γδ T cells using the small molecule inhibitor AX-024 neither reduced the γδ T cells' natural nor the Fab-enhanced tumor killing activity. Likewise, Nck recruitment to CD3ε was not required for intracellular signaling, CD69 and CD25 up-regulation, or cytokine secretion by γδ T cells. Thus, the Nck-CD3ε interaction seems to be dispensable in γδ T cells

Observation of soft X-ray Cherenkov radiation in Al

The soft X-ray radiation generated by 5.7 MeV electrons from both an Al foil and a Mylar film in forward direction was experimentally studied. A narrow specific directivity, an ultra-narrow spectral bandwidth and a good consistency between the experiment and theory prove that the Cherenkov radiation (CR) with photon energy near the L-edge of absorption in Al was observed. The results demonstrate that the CR spectral-angular properties and the absolute photon yield can be described well enough using Pafomov's theoretical model and Henke's refractive index database, which is essential for all practical applications

Pitfalls in the characterization of circulating and tissue-resident human γδ T cells

Dissection of the role and function of human γδ T cells and their heterogeneous subsets in cancer, inflammation, and auto-immune diseases is a growing and dynamic research field of increasing interest to the scientific community. Therefore, harmonization and standardization of techniques for the characterization of peripheral and tissue-resident γδ T cells is crucial to facilitate comparability between published and emerging research. The application of commercially available reagents to classify γδ T cells, in particular the combination of multiple Abs, is not always trouble-free, posing major demands on researchers entering this field. Occasionally, even entire γδ T cell subsets may remain undetected when certain Abs are combined in flow cytometric analysis with multicolor Ab panels, or might be lost during cell isolation procedures. Here, based on the recent literature and our own experience, we provide an overview of methods commonly employed for the phenotypic and functional characterization of human γδ T cells including advanced polychromatic flow cytometry, mass cytometry, immunohistochemistry, and magnetic cell isolation. We highlight potential pitfalls and discuss how to circumvent these obstacles

Heat treatment of glassy carbon implanted with cesium at room and high temperatures

The effect of annealing temperature on the surface morphology and on the diffusion of cesium ions implanted into glassy carbon (Sigradur® G) is reported. The samples were implanted with 360 keV cesium ions to a fluence of 2 × 1016 ions/cm2 at room temperature, at 350 and at 600 °C. The room temperature implanted samples were isochronally vacuum annealed for 1 h at temperatures from 200 to 600 °C. All samples were studied by Rutherford backscattering scattering (RBS) and scanning electron microscopy (SEM). During implantation a strong redistribution of the cesium ions towards the surface is observed, which occurs already at room temperature and enhances at elevated temperatures. However, almost no cesium ions are lost in that process. Contrary, annealing at elevated temperatures results not only in a diffusion and redistribution of cesium, but also in a significant sublimation/evaporation of cesium into the vacuum. This suggests that during implantation some meta-stable compound is formed which prevents a cesium loss. SEM pictures of the samples show that implantation and subsequent annealing strongly influence the surface structure of the glassy carbon.Financial support of the National Research Foundation and the Bundesministerium für Bildung und Forschung (Germany) is gratefully acknowledged.http://www.elsevier.com/locate/nimbhb2013ai201

The scope of language contact as a constraint factor in language change: The periphrasis haber de plus infinitive in a corpus of language immediacy in modern Spanish

In this work an empirical study grounded in the principles and methods of the comparative variationist framework is conducted to measure the scope of language contact as a factor constraining some potentially diverging uses of a Spanish verbal periphrasis that has undergone a sharp decline over the last century (haber de plus infinitive). The analysis is based on three independent samples of text that correspond to three dialectal areas of peninsular Spanish (monolingual zones, Catalan-speaking linguistic territories and the north-western linguistic area). These samples, extracted from a corpus made up of texts of communicative immediacy from the 19th and the first half of the 20th centuries, confirm the existence of a certain linguistic convergence in the expressive habits of the speakers in the bilingual communities. In each region, however, the outcomes are different, due to parallel differences in the structural position of the periphrasis in each language. However, a thorough analysis of the variable context that surrounds the periphrasis shows that the observed differences do not affect the essence of the underlying grammar of this variant, whose decline (which favours tener que plus infinitive and becomes faster as the 20th century advances) is constrained by identical linguistic and extralinguistic conditioning factors in all the dialectal areas