排序方式: 共有187条查询结果,搜索用时 15 毫秒
1.
Manju Lata Rao 《Solid State Communications》2004,129(12):781-784
Bulk amorphous Co(100−x)Ptx (0≤x≤50) nano-alloys have been synthesized using high frequency ultrasound, displaying single domain (4-5 nm) behavior wherein weakly exchange-coupled particles lead to a field-dependent resistivity behavior. Magneto-resistivity is correlated to the order-disorder parameter in these powder compacts. The plot of Δρ/ρ0 as a function of reduced magnetization indicates that all the systems are weakly exchange coupled. 相似文献
2.
Effect of Reactor Pressure on Qualities of GaN Layers Grown by Hydride Vapour Phase Epitaxy 下载免费PDF全文
The influence of reactor pressure on GaN layers grown by hydride vapour phase epitaxy (HVPE) is investigated. By decreasing the reactor pressure from0. 7 to 0.5 mm, the GaN layer growth mode changes from the island-like one to the step flow. The improvements in structural and optical properties and surface morphology of GaN layers are observed in the step flow growth mode. The results clearly indicate that the reactor pressure, similarly to the growth temperature, is One of the important parameters to influence the qualities of GaN epilayers grown by HVPE, due to the change of growth mode. 相似文献
3.
A nonmean-field model for the ripening of two-dimensional islands is presented. In this model, the adatom sea is divided into many small cells that are the polygons of a Voronoi network. The chemical potentials of adatom seas surrounding different islands are different. Strain generated by lattice mismatch is introduced into the model.Computer simulation under periodic boundary conditions is carried out to describe the island ripening in two cases (with and without strain), and demonstrates that small islands may grow faster than large islands, which cannot occur in the mean-field model. The simulated results also show that including strain will slow down the evolution of average island size, and an explanation for this is given. 相似文献
4.
Using the nonrenormalization theorem and Pohlmeyer's theorem, it is proven that there cannot be an asymptotic safety scenario for the Wess–Zumino model unless there exists a non-trivial fixed point with (i) a negative anomalous dimension (ii) a relevant direction belonging to the Kähler potential. 相似文献
5.
We investigate the molecular beam epitaxy growth of metamorphic InxGal-xAs materials (x up to 0.5) on GaAs substrates systematically. Optimization of structure design and growth parameters is aimed at obtaining smooth surface and high optical qualdty. The optimized structures have an average surface roughness of 0.9-1.8 nm. It is also proven by PL measurements that the optical properties of high indium content (55%) InGaAs quantum wells are improved apparently by defect reduction technique and by introducing Sb as a surfactant. These provide us new ways for growing device quality metamorphic structures on GaAs substrates with long-wavelength emissions. 相似文献
6.
Ordered InAs Quantum Dots with Controllable Periods Grown on Stripe-Patterned GaAs Substrates 下载免费PDF全文
GaAs (001) substrates are patterned by electron beam lithography and wet chemical etching to control the nucleation of lnAs quantum dots (QDs). InAs dots are grown on the stripe-patterned substrates by solid source molecular beam epitaxy. A thick buffer layer is deposited on the strip pattern before the deposition of InAs. To enhance the surface diffusion length of the In atoms, InAs is deposited with low growth rate and low As pressure. The AFM images show that distinct one-dimensionally ordered InAs QDs with homogeneous size distribution are created, and the QDs preferentiMly nucleate along the trench. With the increasing amount of deposited InAs and the spacing of the trenches, a number of QDs are formed beside the trenches. The distribution of additional QDs is long-range ordered, always along the trenchs rather than across the spacing regions. 相似文献
7.
8.
R. V. Jolos A. K. Nasirov G. G. Adamian A. I. Muminov 《The European Physical Journal A - Hadrons and Nuclei》2000,8(1):115-124
The effect of shell structure on the distribution of the excitation energy between fragments of the deep inelastic collisions
is analysed in the microscopic approach. It is shown that the density of the single-particle levels of the proton and neutron
subsystems near the Fermi surface determines the ratio between the excitation energies of fragments at the initial stage of
the collision. It is shown also that the shell structure strongly influences the correlations between the width of the charge
distributions and the total kinetic energy losses. Calculations are performed for the 40,48Ca+248Cm reactions. The results obtained suggest a possible interpretation for the observed concentration of the excitation energy
in the light fragment in deep inelastic collisions for a wide range of the total kinetic energy losses.
Received: 27 July 1999 / Accepted: 29 March 2000 相似文献
9.
Mitsuru Ohtake Kouhei Shikada Fumiyoshi Kirino Masaaki Futamoto 《Journal of magnetism and magnetic materials》2008
Co(0 0 0 1)hcp/Fe(1 1 0)bcc epitaxial magnetic bi-layer films were successfully prepared on SrTiO3(1 1 1) substrates. The crystallographic properties of Co/Fe epitaxial magnetic bi-layer films were investigated. Fe(1 1 0)bcc soft magnetic layer grew epitaxially on SrTiO3(1 1 1) substrate with two type variants, Nishiyama–Wasserman and Kurdjumov–Sachs relationships. An hcp-Co single-crystal layer is obtained on Ru(0 0 0 1)hcp interlayer, while hcp-Co layer formed on Au(1 1 1)fcc or Ag(1 1 1)fcc interlayer is strained and may involve fcc-Co phase. It has been shown possible to prepare Co/Fe epitaxial magnetic bi-layer films which can be usable for patterned media application. 相似文献
10.
Properties of Strain Compensated Symmetrical Triangular Quantum Wells Composed of InGaAs/InAs Chirped Superlattice Grown Using Gas Source Molecular Beam Epitaxy 下载免费PDF全文
We investigate the properties of symmetrical triangular quantum wells composed of InGaAs/InAs chirped superlattice, which is grown by gas source molecular beam epitaxy via digital alloy method. In the quantum well structure tensile AlInGaAs are used as barriers to partially compensate for the significant compressive strain in the wells, the strain compensation effects are confirmed by x-ray measurement. The photoluminescence spectra of the sample are dominated by the excitonic recombination peak in the whole temperature range. The thermal quenching, peak energy shift and line-width broadening of the PL spectra are analysed in detail, the mechanisms are discussed. 相似文献