At low temperatures In0.53Ga0.47As samples show an increase of carrier concentration, which can be explained in terms of a two carriers transport model. This type of problem exists since the beginning of the semiconductor era, dating back to monocrystalline germanium.We propose that in all the investigated layers, there are X atoms or charged dislocations in the region of the first monolayers, which are built in during epitaxial growth. The layers were intentionally undoped. They form an impurity band in which low mobility carriers dominate over the localised electron scattering due to the s-d exchange interaction. These carriers do not freeze out at liquid helium temperature and give rise to two transport media for electrons; a conduction band at higher temperatures and an impurity band at lower temperatures. The electron which fall down onto the previously ionised X atoms, then move by thermally activated hopping. We show that the two carriers model for In0.53Ga0.47As epitaxial layers are confirmed by the carrier concentration-temperature, carrier concentration-magnetic field, resistivity-magnetic field behaviour, and also by YKA theory also. The differences between the two transport models are so distinctive that observed phenomena may exist. This paper presents experimental results, which constitute comprehensive evidence for the complicated structure of the semiconductor epitaxial layers on the sample of n-type In0.53Ga0.47As/InP layer with n=2.2×1015/cm3. 相似文献
In [ANISZCZYK, B.-FRANKIEWICZ, R.: Non homeomorphic density topologies, Bull. Polish Acad. Sci. Math. 34 (1986), 211–213] the authors constructed 2c non-homeomorphic density topologies tied to the concept of measure. In [WROŃSKI, S.: The number of non-homeomorphic I-density topologies. Institute of Mathematics of Polish Academy of Sciences. Preprint 482, December 1990, XXXIV Semester in Banach Center, Theory
of Real Functions] an analogous construction has been given for topologies tied to the concept of category. Here we present
a generalization containing both the results mentioned above. This generalization based only on the topological ideas is independent
of the concept of measure or category.
Communicated by L’ubica Holá 相似文献
The Cayley–Klein parameters for the de Sitter groups SO(4, 1) and SO(3, 2) are introduced, and in an extension of the earlier investigation of quasigroups connected with Clifford groups, quasigroups connected with the SO(4, 1) and SO(3, 2) groups are determined. It is shown that these quasigroups have eight-dimensional, double-valued irreducible cracovian representations. The covariance of a five-dimensional form of the Dirac equation with respect to the quasi-rotations forming quasigroups connected with the groups SO(4, 1) and SO(3, 2) is demonstrated. An analogy is drawn between Weyl's hidden symmetry group and a quasigroup. 相似文献
Particle diagnostics of Al-laser-produced plasma based on ion collectors identified three groups of emitted ions. Their velocity distributions were analyzed to obtain the mean ion energy, energy and charge carried by ions, including the angular distributions of these quantities. The electron temperature evaluated from these measurements was compared with X-ray results. A satisfactory agreement between the two sets of data was found. In both the cases the electron temperature grows only very slowly with the incident laser power. Origin of different ion groups is discussed. Iodine photodissociation laser system PERUN was used as a driver. 相似文献
Nuclear resonance studies of the two different types impurity doped potassium hexachloro-stannates, the isomorphic system
such as (K–Rb)2SnCl6 and K2(Sn–Re)Cl6 and the nonisomorphic system K2SnCl6:Al3+ in the high temperature cubic phase revealed contrasting features with one the other characterized by static in the former
and dynamic feature in the latter case respectively. The resonance spectra of the nonisomorphic system indicate additionally
a sign of the local structural transition above the conventional structural phase transition temperature. This seems to be
triggered by the ligand-deficient octahedral defects and can be explained in terms of the enhanced activity of the octahedral
defects for the hindered rotation. 相似文献
Initial curve, major and minor magnetostriction hysteresis loops of the NiFe2O4 ferrite as the functions of static magnetic field were investgated. Magnetostriction hysteresis loops as the functions of static induction are also presented. The experimental phenomenon of “liftoff” value of the magnetostriction loop is detected. 相似文献
The influence of 200 keV Ar-ion irradiation on the interlayer coupling in the Fe/Cr multilayer system exhibiting the giant magnetoresistance effect (GMR) is studied by conversion electron Mössbauer spectroscopy (CEMS), VSM hysteresis loops, magnetoresistivity and electric resistivity measurements and supplemented by the small-angle X-ray diffraction (SAXRD). The increase of Ar ion dose causes an increase of interface roughness, as evidenced by the increase of the Fe step-sites detected by CEMS as a result of which the GMR gradually decreases and vanishes at doses exceeding 1×1014 Ar/cm2. A degradation of GMR with increasing Ar-ion dose is related to the formation of pinholes between Fe layers and the decrease of the antiferromagnetically coupled fraction.