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1.
A. Quesada M. A. García J. de la Venta E. Fernández Pinel J. M. Merino A. Hernando 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(4):457-461
The future of the spintronic technology requires the development of magnetic semiconductor materials. Most research groups
have focused on diluted
magnetic semiconductors because of the promising theoretical predictions and
initial results. In this work, the current experimental situation of ZnO
based diluted magnetic semiconductors is presented. Recent results on
unexpected ferromagnetic-like behaviour in different nanostructures are also
revised, focusing on the magnetic properties of Au and ZnO nanoparticles
capped with organic molecules. These experimental observations of magnetism
in nanostructures without the typical magnetic atoms are discussed. The
doubts around the intrinsic origin of ferromagnetism in diluted magnetic
semiconductors along with the surprising magnetic properties in absence of
the typical magnetic atoms of certain nanostructures should make us consider
new approaches in the quest for room temperature magnetic semiconductors. 相似文献
2.
稀磁半导体--自旋和电荷的桥梁 总被引:5,自引:0,他引:5
稀磁半导体可能同时利用载流子的自旋和电荷自由度构造将磁、电集于一体的半导体器件.尤其是铁磁半导体材料的出现带动了半导体自旋电子学的发展.室温铁磁半导体材料的制备,半导体材料中有效的自旋注入,以及自旋在半导体结构中输运和操作已成为目前半导体自旋电子学领域中的热门课题.稀磁半导体呈现出强烈的自旋相关的光学性质和输运性质,这些效应为人们制备半导体自旋电子学器件提供了物理基础. 相似文献
3.
A formula for carrier concentration, and a relationship between mobility and diffusivity, have been presented for degenerate
semiconductors with a nonparabolic energy band structure under the influence of a magnetic field. The relationships are general;
they involve no approximation related to the comparative values of energy bandgap and spin orbit coupling. They should therefore,
be applicable to both non-degenerate and degenerate semiconductors. They are quite suitable for the investigation of electrical
transport in heavily doped semiconductors under the influence of a magnetic field.
PACS 72.20.-I; 73.50.-h 相似文献
4.
Transport properties of doped Bi_2Se_3 and Bi_2Te_3 topological insulators and heterostructures
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In this review article, the recent experimental and theoretical research progress in Bi_2Se_3-and Bi_2Te_3-based topological insulators is presented, with a focus on the transport properties and modulation of the transport properties by doping with nonmagnetic and magnetic elements. The electrical transport properties are discussed for a few different types of topological insulator heterostructures, such as heterostructures formed by Bi_2Se_3-and Bi_2Te_3-based binary/ternary/quaternary compounds and superconductors, nonmagnetic and magnetic metals, or semiconductors. 相似文献
5.
The paper reviews the recent year publications concerning organic field-effect transistors (OFETs). A lot of works have been
performed to help understanding the structural and electrical properties of materials used to construct OFETs. It has been
established that in partially ordered systems, the charge transport mechanism is thermally activated and field-assisted hopping
transport and the hopping transport between disorder-induced localized states dominate over intrinsic polaronic hopping transport
seen in organic single crystals. Many research attempts have been carried out on the design of air-stable organic semiconductors
with a solution process which is capable of producing OFETs with excellent properties and good stability when subjected to
multiple testing cycles and under continuous electrical bias. Recent experiments have demonstrated ambipolar channel conduction
and light emission in conjugated polymer FETs. These achievements are the basis for construction of OLED based displays driven
by active matrix consisting of OFETs. 相似文献
6.
Influence of surface scattering on the thermal properties of spatially confined GaN nanofilm
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Gallium nitride(GaN), the notable representative of third generation semiconductors, has been widely applied to optoelectronic and microelectronic devices due to its excellent physical and chemical properties. In this paper, we investigate the surface scattering effect on the thermal properties of GaN nanofilms. The contribution of surface scattering to phonon transport is involved in solving a Boltzmann transport equation(BTE). The confined phonon properties of GaN nanofilms are calculated based on the elastic model. The theoretical results show that the surface scattering effect can modify the cross-plane phonon thermal conductivity of GaN nanostructures completely, resulting in the significant change of size effect on the conductivity in GaN nanofilm. Compared with the quantum confinement effect, the surface scattering leads to the order-of-magnitude reduction of the cross-plane thermal conductivity in GaN nanofilm. This work could be helpful for controlling the thermal properties of Ga N nanostructures in nanoelectronic devices through surface engineering. 相似文献
7.
Zn1-xMnxO bulks have been prepared by the solid state reaction method. Zn vapor treatment has been carried out to adjust the carrier concentration. For the Zn treated Zn1-xMnxO bulks, analysis of the temperature dependence of resistance and the field dependence of magnetoresistance demonstrates that the bound magnetic polarons (BMPs) play an important role in the electrical transport behavior. The hopping of BMPs dominates the electrical conduction behavior when temperature is below 170 K. At low temperature,paramagnetic Zn1-xMnxO bulks show a large magnetoresistance effect,which indicates that the large magnetoresistance effect in transition-metal doped ZnO dilute magnetic semiconductors is independent of their magnetic states. 相似文献
8.
Mahendra Singh Sodha Yatendra Pal Varshni 《Zeitschrift für Physik A Hadrons and Nuclei》1959,153(5):555-562
Hall mobility and other transport properties of the electrons inn-type of semiconductors have been investigated when a magnetic field is applied, taking into account electron-electron scattering. Results have been presented for different impurity densities. 相似文献
9.
《Current Applied Physics》2003,3(5):461-464
Recent materials research has advanced the maximum ferromagnetic transition temperature in semiconductors containing magnetic elements toward room temperature. Reaching this goal would make information technology applications of these materials likely. In this article we briefly review the status of work over the past five years which has attempted to achieve a theoretical understanding of these complex magnetic systems. The basic microscopic origins of ferromagnetism in the (III,Mn)V compounds that have the highest transition temperatures appear to be well understood, and efficient computation methods have been developed which are able to model their magnetic, transport, and optical properties. However many questions remain. 相似文献
10.
Punita Srivastava Pushpendra Kumar Kedar Singh 《Journal of nanoparticle research》2011,13(10):5077-5085
Manipulation of carrier spins in semiconductors for spintronics applications has received great attention driven by improved
functionalities and higher speed operation. Doping of semiconductor nanocrystals by transition-metal ions pronounced as diluted
magnetic semiconductors (DMS) has attracted tremendous attention. Such doping is, however, difficult to achieve in low-dimensional
strongly quantum-confined nanostructures by conventional growth procedures. In the present case, magic-sized, pure, and Cr-doped
CdS DM-QDs have been synthesized by solution phase chemistry (lyothermal method). Structural, optical, and magnetic investigation
suggest an intrinsic nature of ferromagnetism with highly quantum-confined system. Optical and magnetic results of pure and
doped QDs reveal major physical consequences of dopant localization within the capacity to engineer dopant-carrier exchange
interactions introducing magnetic functionalities within the host semiconductor lattice. Unpaired Cr ions in Cd substitutional
sites could create spin ordering and ferromagnetic coupling. The results presented herein illustrate some of the remarkable
and unexpected complexities that can arise in doped QDs. 相似文献
11.
We have theoretically investigated electric-field and magnetic-field effects on electronic transport properties in nanostructures consisting of realistic magnetic barriers created by lithographic patterning of ferromagnetic or superconducting films. The results indicate that the characteristics of transmission resonance are determined not only by the magnetic configuration and the incident wave vector but also strongly by the applied electric and magnetic fields. It is shown that transmission resonance shifts towards the low-energy region by applying the electric field, and that with increasing the electric field transmission resonance is suppressed for the entire incident wave vector in the magnetic nanostructures with antisymmetric magnetic profile, while for the magnetic nanostructures with symmetric magnetic profile transmission resonance is enhanced for certain incident wave vector. It is also shown that both transmission and conductance shift towards high-energy direction and are greatly suppressed with the increase of the external magnetic field.Received: 20 May 2003, Published online: 11 August 2003PACS:
73.40.Gk Tunneling -
73.23.-b Electronic transport in mesoscopic system -
75.70.Cn Interfacial magnetic properties (multilayers, superlattices) 相似文献
12.
Epitaxial synthesis and properties of novel Co and Mn-doped Ge magnetic semiconductors were studied. Epitaxial growth of high quality films with high doping concentrations has been stabilized by the use of two dopants. The magnetic and transport properties of the system exhibit high T(C) and large magnetoresistance effects that can be controlled systematically by the doping concentration. The maximum T(C) achieved in the semiconducting materials is approximately 270 K at a composition of Co0.12Mn0.03Ge0.85. 相似文献
13.
E. Comini G. Faglia M. Ferroni G. Sberveglieri 《Applied Physics A: Materials Science & Processing》2007,88(1):45-48
Progress has been achieved in the synthesis, structural characterization and physical properties investigation of nanostructures.
We have focused our attention on zinc oxide nanostructures. We report on the growth of ZnO nanostructures using vapour phase
technique. We have synthesized, depending on the growth conditions, different nanostructures such as wires and combs of zinc
oxide. ZnO nanowires electrical properties have been characterised in presence of different gases, the results highlight remarkable
response to acetone and ethanol with detection limits lower than 1 ppm.
PACS 73.63.Bd; 74.78.Na 相似文献
14.
P. D. Grigoriev A. A. Sinchenko K. K. Kesharpu A. Shakin T. I. Mogilyuk A. P. Orlov A. V. Frolov D. S. Lyubshin D. A. Chareev O. S. Volkova A. N. Vasiliev 《JETP Letters》2017,105(12):786-791
A theoretical model has been proposed to describe the conductivity of a layered anisotropic normal metal containing small superconducting inclusions at an arbitrary eccentricity of spheroidal superconducting islands. The electron transport and magnetic properties of FeSe single crystals have been measured. The results indicate the existence of superconductivity at temperatures much higher than the critical superconducting transition temperature corresponding to vanishing electrical resistance. Within the proposed model, quantitative agreement has been achieved between the volume fraction of superconducting inclusions and its temperature dependence determined from the transport and magnetic measurements. 相似文献
15.
《中国物理 B》2019,(9)
Magnetic oxide semiconductors are significant spintronics materials.In this article, we review recent advances for homogeneous and inhomogeneous magnetic oxide semiconductors.In the homogeneous magnetic oxide semiconductors,we focus on the various doping techniques including choosing different transition metals, codoping, non-magnetic doping,and even un-doping to realize homogeneous substitution and the clear magnetic origin.And the enhancement of the ferromagnetism is achieved by nanodot arrays engineering, which is accompanied by the tunable optical properties.In the inhomogeneous magnetic oxide semiconductors, we review some heterostructures and their magnetic and transport properties, especially magnetoresistance, which are dramatically modulated by electric field in the constructed devices.And the related mechanisms are discussed in details.Finally, we provide an overview and possible potential applications of magnetic oxide semiconductors. 相似文献
16.
Yoshio Watanabe 《Synchrotron Radiation News》2013,26(3)
Progress in nanofabrication technology has led to the development of nanostructure materials with characteristic physical properties and potential applications in micro- and optoelectronic devices. To evaluate such nanostructures, different spectroscopic techniques have been developed that can provide a nanometer-scale lateral resolution. The International Workshop on Nanoscale Spectroscopy (NSS) is a biennial meeting series to share information on the latest research advances of science and technology, which include various kinds of nanoscale spectroscopies; electronic, optical, magnetic, mechanical, and transport properties of nanoscale systems; nanoscale devices; and nanomanipulation. 相似文献
17.
Yasuo Oka 《Physics of the Solid State》1998,40(5):778-780
Excitonic properties and the dynamics are reported in quantum dots (QDs) and quantum wells (QW) of diluted magnetic semiconductors.
Transient spectroscopies of photoluminescence and nonlinear-optical absorption and emission have been made on these quantum
nanostructures. The Cd1−x
MnxSe QDs show the excitonic magnetic polaron effect with an increased binding energy. The quantum wells of the Cd1−x
MnxTe/ZnTe system display fast energy and dephasing relaxations of the free and localized excitons as well as the tunneling process
of carriers and excitons in the QWs depending on the barrier widths. The observed dynamics and the enhanced excitonic effects
are the inherent properties of the diluted magnetic nanostructures.
Fiz. Tverd. Tela (St. Petersburg) 40, 846–848 (May 1998)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
18.
R. Martins P. Barquinha L. Pereira I. Ferreira E. Fortunato 《Applied Physics A: Materials Science & Processing》2007,89(1):37-42
This paper aims to discuss the effect of order and disorder on the electrical performances of covalent silicon semiconductors
and ZnO based ionic oxide semiconductors used as active channel layers in thin film transistors. The effect of disorder on
covalent semiconductors directly affects their electrical transport properties due to the asymmetric behaviour of sp states,
while in ionic oxide semiconductors it is found that this effect is small due to the fact that angular disorder has no effect
on the spherical symmetry of s states. To this we must add that the mobility of carriers in both systems is quite different,
being also affected by electron–phonon interactions (weak in silicon and strong in ionic oxides leading to formation of polarons).
Besides, the impurity doping effect and the presence of vacancies in disordered silicon and in ionic oxides behave differently,
which will influence the thin film properties and so, the performances of the devices produced.
PACS 81.05.Gc; 81.05.Hd; 85.30.Tv 相似文献
19.
Quasi-one-dimensional (1D) nanostructures, such as nanowires, nanobelts and nanorods, are the forefront materials for nanotechnology. To date, such nanostructures have been synthesized for a wide range of semiconductors and oxides, and they are potential building blocks for fabricating numerous nano-scale devices. 1D ZnO nanostructures, due to its unique semiconducting, piezoelectric, and bio-safe properties, have received wide attention. From structure point of view, a common characteristic of ZnO nanostructures is that they are mostly dislocation-free. However, planar and point defects do frequently exist in such nanostructures. The objective of this paper is to present detailed electron microscopy study about the structures of planar defects, such as stacking faults, twins, inversion domain walls that existed in 1D ZnO nanostructures. These planar defects are important for understanding the growth mechanism and relevant physical and possibly chemical properties of 1D ZnO nanostructures. 相似文献
20.
The possibility of half-metallic antiferromagnetism, a special case of ferrimagnetism with a compensated magnetization, in the diluted magnetic semiconductors is highlighted on the basis of the first-principles electronic structure calculation. As typical examples, the electrical and magnetic properties of II-VI compound semiconductors doped with 3d transition metal ion pairs--(V, Co) and (Fe, Cr)--are discussed. 相似文献