6,242 research outputs found
Ge1-ySny (y=0.01-0.10) alloys on Ge-buffered Si: Synthesis, microstructure, and optical properties
No full textabstract: Novel hydride chemistries are employed to deposit light-emitting Ge [subscript 1- y] Sn [subscript y] alloys with y ≤ 0.1 by Ultra-High Vacuum Chemical Vapor Deposition (UHV-CVD) on Ge-buffered Si wafers. The properties of the resultant materials are systematically compared with similar alloys grown directly on Si wafers. The fundamental difference between the two systems is a fivefold (and higher) decrease in lattice mismatch between film and virtual substrate, allowing direct integration of bulk-like crystals with planar surfaces and relatively low dislocation densities. For y ≤ 0.06, the CVD precursors used were digermane Ge [subscript 2]H[subscript 6] and deuterated stannane SnD[subscript 4]. For y ≥ 0.06, the Ge precursor was changed to trigermane Ge [subscript 3]H[subscript 8], whose higher reactivity enabled the fabrication of supersaturated samples with the target film parameters. In all cases, the Ge wafers were produced using tetragermane Ge [subscript 4]H[subscript 10] as the Ge source. The photoluminescence intensity from Ge [subscript 1− y] Sn [subscript y] /Ge films is expected to increase relative to Ge [subscript 1− y] Sn [subscript y] /Si due to the less defected interface with the virtual substrate. However, while Ge [subscript 1− y] Sn [subscript y] /Si films are largely relaxed, a significant amount of compressive strain may be present in the Ge [subscript 1− y] Sn [subscript y] /Ge case. This compressive strain can reduce the emission intensity by increasing the separation between the direct and indirect edges. In this context, it is shown here that the proposed CVD approach to Ge [subscript 1− y] Sn [subscript y] /Ge makes it possible to approach film thicknesses of about 1 μm, for which the strain is mostly relaxed and the photoluminescence intensity increases by one order of magnitude relative to Ge [subscript 1− y] Sn [subscript y] /Si films. The observed strain relaxation is shown to be consistent with predictions from strain-relaxation models first developed for the Si[subscript 1− x] Ge [subscript x] /Si system. The defect structure and atomic distributions in the films are studied in detail using advanced electron-microscopy techniques, including aberration corrected STEM imaging and EELS mapping of the average diamond–cubic lattice.Copyright 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. along with the following message: The following article appeared in 116, 13 (2014) and may be found at http://dx.doi.org/10.1063/1.489678
Atomic layer deposition of crystalline SrHfO3 directly on Ge (001) for high-k dielectric applications
No full textabstract: The current work explores the crystalline perovskite oxide, strontium hafnate, as a potential high-k gate dielectric for Ge-based transistors. SrHfO3 (SHO) is grown directly on Ge by atomic layer deposition and becomes crystalline with epitaxial registry after post-deposition vacuum annealing at ∼700 °C for 5 min. The 2 × 1 reconstructed, clean Ge (001) surface is a necessary template to achieve crystalline films upon annealing. The SHO films exhibit excellent crystallinity, as shown by x-ray diffraction and transmission electron microscopy. The SHO films have favorable electronic properties for consideration as a high-k gate dielectric on Ge, with satisfactory band offsets (>2 eV), low leakage current (<10[superscript −5] A/cm[superscript 2] at an applied field of 1 MV/cm) at an equivalent oxide thickness of 1 nm, and a reasonable dielectric constant (k ∼ 18). The interface trap density (Dit ) is estimated to be as low as ∼2 × 10[superscript 12] cm[superscript −2] eV[superscript −1] under the current growth and anneal conditions. Some interfacial reaction is observed between SHO and Ge at temperatures above ∼650 °C, which may contribute to increased Dit value. This study confirms the potential for crystalline oxides grown directly on Ge by atomic layer deposition for advanced electronic applications.Copyright 2015 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. along with the following message: The following article appeared in JOURNAL OF APPLIED PHYSICS 117, 5 (2015) and may be found at http://dx.doi.org/10.1063/1.490695
OB00040 - Damodarpur Copper Plate 1 (GE 163) of Budhagupta
No full textDamodarpur Copper Plate 1 (GE 163) of Budhagupt
Distribution and substitution mechanism of Ge in a Ge-(Fe)-bearing sphalerite
No full textMass Spectrometry shows that Ge is enriched in the same bands as Fe, and that Ge-rich sphalerite also contains measurable levels of several other minor elements, including As, Pb and Tl. Micron- to nanoscale heterogeneity in the sample, both textural and compositional, is revealed by investigation using Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM) combined with Synchrotron X-ray Fluorescence mapping and High-Resolution Transmission Electron Microscopy imaging of FIB-prepared samples. Results show that Ge is preferentially incorporated within Fe-rich sphalerite with textural complexity finer than that of the microbeam used for the X-ray Absorption Near Edge Structure (XANES) measurements. Such heterogeneity, expressed as intergrowths between 3C sphalerite and 2H wurtzite on [110] zones, could be the result of either a primary growth process, or alternatively, polystage crystallization, in which early Fe-Ge-rich sphalerite is partially replaced by Fe-Ge-poor wurtzite. FIB-SEM imaging shows evidence for replacement supporting the latter. Transformation of sphalerite into wurtzite is promoted by (111)* twinning or lattice-scale defects, leading to a heterogeneous ZnS sample, in which the dominant component, sphalerite, can host up to ~20% wurtzite. Ge K-edge XANES spectra for this sphalerite are identical to those of the germanite and argyrodite standards and the synthetic chalcogenide glasses GeS₂ and GeSe₂, indicating the Ge formally exists in the tetravalent form in this sphalerite. Fe K-edge XANES spectra for the same sample indicate that Fe is present mainly as Fe²+, and Cu K-edge XANES spectra are characteristic for Cu+. Since there is no evidence for coupled substitution involving a monovalent element, we propose that Ge⁴+ substitutes for (Zn²+, Fe²+) with vacancies in the structure to compensate for charge balance. This study shows the utility of synchrotron radiation combined with electron beam micro-analysis in investigating low-level concentrations of minor metals in common sulfides.Nigel J. Cook, Barbara Etschmann, Cristiana L. Ciobanu, Kalotina Geraki, Daryl L. Howard, Timothy Williams, Nick Rae, Allan Pring, Guorong Chen, Bernt Johannessen, and Joël Brugge
Recommended from our members
IR Properties of Ge-Doped CH - A Continuation
No full textWe have reexamined Ge-doped CH and have found that the material is more reactive to air than previously understood. The Ge-doped material as formed shows by IR the presence of a Ge-H linkage that oxidizes rapidly, giving rise to a significant OH absorption. This broad peak impacts IR layering wavelengths of interest
[[alternative]]Raman Study of Folded Acoustic Phonons in Si/Ge Superlattice
No full text[[abstract]]This research presents three Raman Spectrums of Si/Ge superlattices growing on the substrate of Si by MBE. The period of superlattice samples N=5, the growing conditions of superlattice are: the Si-layer is 50nm；the Ge-layers are 2.2nm、3.8nm and 5.4nm. Measuring by TEM of samples firstly, the Si-layers are 50.18nm、48.65 nm and 48.89 nm；the Ge-layers are 2.46 nm、3.78 nm and 4.44 nm。
In the Spectrum, the peak of Si-Si mode is quite obvious；The peak of Ge-Ge mode is comparatively weak. In the room temperature, the peak of Si-Ge mode is quite unobvious due to the fewer periods.
Raman Spectrum of three superlattices shows many and obvious folded phonon signals in the low frequency (0 ~100 cm-1) area , so does the doublets of phonon are quite obvious. Fittting the frequency of folded phonons by Rytov’s theory finds that the Si-layers are 49.65nm、45.98 nm and 45.95 nm, the Ge-layers are 2.12 nm、3.78 nm and 5.01 nm. All the errors are within 6%, so Rytov’s theory is a good foundation to study Raman Spectrum of superlattice.
Fitting the intensity of folded spectrum of phonon with photoelastic mode , in the wavelength far away the energy of resonance ( As 476 nm) can get good result. Also getting the ratio of Si-layer thickness and the period of superlattice are 0.96（632 nm）、0.93（476 nm）and 0.93（476 nm）, compared with the result of fitting frequency of folded phonon by Rytov’s theory：0.96、0.92及0.90, matchs very well, except the 3% difference of sample-N107.
Besides, examining Ge-Ge mode in the spectrum with LCM, the roughness of Ge-layer can be examed, and the calculating layers are 2.22nm、3.83 nm and 5.37 nm, the difference is within 7% comparing with the result of fitting phonons.
In the various temperature (10 K~300 K) Raman Sprctrum, there are signals of continuous scattering of phonons around 200 cm-1 , and the lower the temperature, or the thinner the Ge-layer, the more obvious the continuous scattering of phonon is. We can find the phenomenon that E1 energy of Ge-layer is in the vicinity of 2.3 eV and distributed widely ,when we observe the folded phonon in low frequency, the resonance of Ge-Ge Mode, and the fluorescence in high frequency.
Diamphidaxona (Diamphidaxonella) californica Smith & Cook, 2006, sp. nov.
No full textDiamphidaxona (Diamphidaxonella) californica sp. nov. (Figs. 81–86) Description. Male with character states of Diamphidaxonella (female unknown). Dorsal edge of camerostome acutely rounded anteriorly (Fig. 82). Pedipalps with tibia bearing one ventral seta (Fig. 83). Dorsal shield with anterior plate narrower than posterior plate and protruding and strongly pointed anteriorly (Fig. 81). Ventral shield with suture lines between third and fourth coxal plates with medial loops deeply arched and lateral loops Ushaped and open anteriorly (Fig. 82). Projections covering insertions of fourth pair of legs with anterior extensions moderately long, sinuous and directed anterolaterally (Fig. 82). Genital field of males separated from ventral shield by distinct band of membranous integument (Fig. 82). Measurements of holotype: Male (n= 1): Length/width anterior dorsal plate 138 / 186, length/width posterior dorsal plate 246 / 192, length/width ventral shield 348 / 222, length/width genital field 50 / 78. Lengths pedipalp segments: Tr 10, Fe 36, Ge 20, Ti 26, Ta 18. Lengths leg segments: ITr 25, IBFe 36, ITFe 34, IGe 42, ITi 46, ITa 56; IITr 30, IIBFe 38, IITFe 34, IIGe 39, IITi 46, IITa 56; IIITr 31, IIIBFe 36, IIITFe 33, IIIGe 40, IIITi 52, IIITa 60; IVTr 78, IVBFe 51, IVTFe 56, IVGe 61, IVTi 61, IVTa 62. Types. Holotype: Male from South Fork of Trinity River at Forest Glen Campground off Rt. 36 at Forest Glen, Trinity Co., California on 6 August 1987 by IMS (slide, CNC). Etymology. Named for the state of California where the only known specimen of this species was collected. Distribution. Known only from the type locality. Remarks. The holotype of Diamphidaxona californica differs from adults of all other known North American species of the subgenus Diamphidaxonella in that the anterior dorsal plate protrudes and is strongly pointed anteriorly.Published as part of Smith, Ian M. & Cook, David R., 2006, North American species of Diamphidaxona (Acari: Hydrachnida: Hygrobatidae), pp. 1-44 in Zootaxa 1279 on pages 21-22, DOI: 10.5281/zenodo.17337
The English Translation of the Epitaph of the Wu Kingdom Transcendent Duke Ge of the Left Palace of the Grand Bourne by Tao Hongjing
No full textabstract: This thesis is a translation and analysis of the “Epitaph of the Wu Kingdom
Transcendent Duke Ge of the Left Palace of the Grand Bourne” (Epitaph below). The author was Tao Hongjing (456 CE-536 CE). The subject of this Epitaph inscribed on a stele was Ge Xuan (trad. 164 CE-244 CE). Ge Xuan had two titles attributed to him by later Daoists. According to the Lingbao scriptures, Ge was appointed by the Perfected of Grand Bourne, a heavenly title. Later, in the Shangqing scriptures, Ge Xuan was said to be an earthly transcendent without any heavenly appointment. This debate occurred before Tao Hongjing began to write. This stele epitaph is essential, as it records sayings from both Lingbao and Shangqing scriptures. By reading this translated epitaph, scholars can know more about different versions of Ge Xuan's legend, as well as how Ge Xuan's legend was constantly rewritten by later Daoists.Dissertation/ThesisMasters Thesis Religious Studies 202
- …
