5,244 research outputs found
Associations of individual, household and environmental characteristics with carbon dioxide emissions from motorised passenger travel
No full textCarbon dioxide (CO2) emissions from motorised travel are hypothesised to be associated with individual, household, spatial and other environmental factors. Little robust evidence exists on who contributes most (and least) to travel CO2 and, in particular, the factors influencing commuting, business, shopping and social travel CO2. This paper examines whether and how demographic, socio-economic and other personal and environmental characteristics are associated with land-based passenger transport and associated CO2 emissions. Primary data were collected from 3474 adults using a newly developed survey instrument in the iConnect study in the UK. The participants reported their past-week travel activity and vehicle characteristics from which CO2 emissions were derived using an adapted travel emissions profiling method. Multivariable linear and logistic regression analyses were used to examine what characteristics predicted higher CO2 emissions. CO2 emissions from motorised travel were distributed highly unequally, with the top fifth of participants producing more than two fifth of emissions. Car travel dominated overall CO2 emissions, making up 90% of the total. The strongest independent predictors of CO2 emissions were owning at least one car, being in full-time employment and having a home-work distance of more than 10 km. Income, education and tenure were also strong univariable predictors of CO2 emissions, but seemed to be further back on the causal pathway than having a car. Male gender, late-middle age, living in a rural area and having access to a bicycle also showed significant but weaker associations with emissions production. The findings may help inform the development of climate change mitigation policies for the transport sector. Targeting individuals and households with high car ownership, focussing on providing viable alternatives to commuting by car, and supporting planning and other policies that reduce commuting distances may provide an equitable and efficient approach to meeting carbon mitigation target
Dispersion modelling for decision-making: combining spatial statistics with model parameterisation
No full text
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
[[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.
SECURE (SElf Conserving URban Environments) project: the route to delivering transport sustainability
No full text- …
