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排序方式: 共有673条查询结果,搜索用时 31 毫秒
1.
2.
G. Hanna T. Glatzel S. Sadewasser N. Ott H.P. Strunk U. Rau J.H. Werner 《Applied Physics A: Materials Science & Processing》2006,82(1):1-7
The influence of different film textures on the electronic properties of polycrystalline Cu(In,Ga)Se2 absorbers is studied by measuring the laterally resolved optoelectronic properties of differently textured Cu(In,Ga)Se2 films with Kelvin probe force microscopy and cathodoluminescence. The grain boundaries in (112)- and (220/204)-textured films behave differently. The work-function profile measured with the Kelvin probe across a grain boundary in (112)-textured films shows a dip indicating positive charges at the grain boundaries. In panchromatic cathodoluminescence mappings in a transmission electron microscope, such grain boundaries appear dark, i.e. the strongly reduced luminescence indicates that the grain boundaries represent strong non-radiative recombination centers. In contrast, grain boundaries in (220/204)-textured films give rise to a dip or a step in the work function indicating slightly negative charge or neutrality. Cathodoluminescence is reduced at such grain boundaries, but less dramatically than in the (112)-textured case. However, when Na is present in the (220/204)-textured films, the grain boundaries are almost invisible in cathodoluminescence mappings. This strong passivating action of Na occurs only in the (220/204)-textured films, due to a particular grain-boundary population. In (112)-textured films and films without pronounced texture, this passivation effect is much less noticeable. PACS 73.50.Gr; 73.61.Ga; 78.60.Hk; 87.64.Dt 相似文献
3.
It is wellknown that the technique of character sums together with the tools of algebraic number theory is the adequate method for the study of difference sets in abelian groups, compare for instance Ott [5] or Turyn [6]. In this paper we use this method to prove a new non-existence theorem for certain difference sets in abelian groups of order rpa rp^a , where r 1 2 r \neq 2 and p are distinct primes. 相似文献
4.
We show that a theorem of Shchepin and Repovš concerning the smoothness of compacta follows from the theory of semicontinuous relations. 相似文献
5.
S. Barth H. R. Ott F. N. Gygax B. Hitti E. Lippelt A. Schenck Z. Fisk 《Hyperfine Interactions》1989,50(1-4):709-716
μ+ SR-measurements in transversally applied magnetic fields of 2000 G and 4000 G on heavy-electron single crystal U2Zn17 are presented. They reveal that at least two types of interstitial sites are occupied by the positive muons. One of these
sites (1/3, 2/3, 5/6) could be identified via induced local dipolar fields which aboveT
N=9.7 K can exactly be derived from the magnetic susceptibility. The corresponding component of the μ+-signal exhibits a steplike decrease by about 40% atT
N which is caused by the onset of a very broad distribution of static internal magnetic fields (ΔB≈1000 G) with zero average. Such a field distribution is in distinct contrast to dipolar-field calculations performed for
the simple antiferromagnetic structure deduced from neutron diffraction. The remaining 60% of the muons contributing to this
component belowT
N are subject to a narrow static field distribution (ΔB≈1 G). The induced dipolar fields at the site (1/3, 2/3, 5/6) are temperature-independent belowT
N. A weak dipolar coupling to the U-moments renders similar observations for muons occupying the second type of interstitial
impossible. 相似文献
6.
Consider discrete storage processes that are modulated by environmental processes. Environmental processes cause interruptions in the input and/or output processes of the discrete storage processes. Due to the difficulties encountered in the exact analysis of such discrete storage systems, often Poisson flow and/or fluid flow models with the same modulating environmental processes are proposed as approximations for these systems. The analysis of Poisson flow and fluid flow models is much easier than that of the discrete storage processes. In this paper we give sufficient conditions under which the content of the discrete storage processes can be bounded by the Poisson flow and the fluid flow models. For example, we show that Poisson flow models and the fluid flow models developed by Kosten (and by Anick, Mitra and Sondhi) can be used to bound the performance of infinite (finite) source packetized voice/data communication systems. We also show that a Poisson flow model and the fluid flow model developed by Mitra can be used to bound the buffer content of a two stage automatic transfer line. The potential use of the bounding techniques presented in this paper, of course, transcends well beyond these examples.Supported in part by NSF grant DMS-9308149. 相似文献
7.
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9.
A. Dönni P. Fischer A. Furrer P. Bonville F. Hulliger H. R. Ott 《Zeitschrift für Physik B Condensed Matter》1990,81(1):83-88
A polycrystalline smaple of nonstoichiometric ytterbium phosphide, YbP0.84, was investigated by neutron scattering, Mössbauer spectroscopy and bulk magnetic measurements. Neutron diffraction experiments prove the existence of antiferromagnetic type II ordering belowT
N
=0.64 K, in contrast to the observed antiferromagnetic type III ordering in the stoichiometric Kondo-like compounds YbN and YbAs. The temperature dependence of the average ordered magnetic moment per Yb3+ ion with saturation value Yb = 1.03(7)
B
is similar to that of YbN. Mössbauer experiments prove the magnetic phase transition to be first order with different regions in the sample having slightly different transition temperatures. By means of inelastic neutron scattering the crystal-field level scheme was established to be
6 –
8(19meV) –
7(43meV). 相似文献
10.