检索结果-南通市图书馆

electrical properties of ^(70)Ge:Ga near the metal–insulator transition

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Semiconductors 2015年第6期36卷 1-5页

作者： M Errai a el kaaouachi H el idrissi Laboratoire MSTI Ecole Supérieure de tecchnologie d'Agadir B.P: 33/S University Ibn ZohrFaculty of Sciences AgadirMorocco Laboratoire electronique électrotechnique Automatique et Traitement de l'Information Département Génie Electrique Faculté des Sciences et Techniques de Mohammedia Université Hassan II Mohammedia CasablancaBP 146 Quartier YasminaMohammedia

The results of the metal-insulator transition （MIT） induced by impurity concentration are presented in the case of metallic and insulating samples 70Ge：Ga p-type. The eight samples studied have Ga concentrations N ranging from 1.848 × 1017 to 1.912 × 10^17 cm-3. The conductivity measurements were carried out at low temperature in the range 1 to 0.019 K. We provide physical explanations to explain the behaviors of the temperature dependence of the electrical conductivity in both sides of the MIT. The data are for a 70Ge：Ga sample prepared and reported by Itoh et aL in Ref. [Itoh K M, Watanabe M, Ootuka Y, et al. J Phys Soc Jpn, 2004, 73（1）： 173].

关键词： 70Ge: Ga semiconductor low temperature impurity concentration metal-insulator variable rangehopping conductivity transport properties

A crossover from Efros–Shklovskii hopping to activated transport in a GaAs two-dimensional hole system at low temperatures

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Semiconductors 2021年第5期42卷 60-63页

作者： S.Dlimi A.el kaaouachi L.Limouny B.A.Hammou Physics Department Faculty of SciencesIbn Zohr UniversityBP 8106Hay Dakhla80000 AgadirMorocco Materials and Physicochemistry of the Atmosphere and Climate Group Faculty of SciencesIbn Zohr UniversityBP 810680000 AgadirMorocco

In this paper, we discuss low-temperature hopping-conductivity behavior in the insulating phase, in the absence of a magnetic field. We conduct a theoretical study of the crossover from hopping to activated transport in a GaAs two-dimensional hole system at low temperatures, finding that a crossover takes place from the Efros-Shklovskii variable-range hopping(VRH)regime to an activated regime in this system. This conductivity behavior in p-GaAs quantum wells is qualitatively consistent with the laws laid down in theories of localized electron interactions. Given sufficiently strong interactions, the holes in the localized states are able to hop collectively.

关键词： quantum wells 2D GaAs heterostructues transport properties variable range hopping

Negative Magnetoresistance Behaviour and Variable Range Hopping Conduction in Insulating NbSi Amorphous Alloys at Very Low Temperature with aagnetic Field

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Physics 2012年第7期3卷 521-528页

作者： Abdelghani Sybous Abdelhamid el kaaouachi Jamal Hemine Abdelfattah Narjis Lhoussine Limouny Said Dlimi Rachid Abdia Gerard Biskupski Laboratoire de Physique de la Matière Condensée Faculté des Sciences et Techniques de Mohammadia Département de Physique Mohammedia Morocco Laboratoire de Spectroscopie Hertzienne LSH Batiment P5 Université des Sciences et Technologies de LilleI 59 655 Villeneuve d’Ascq Cedex France Research Group in ESNPS Physics Department University Ibn Zohr Faculty of Sciences B.P 8106 Hay Dakhla Agadir Morocco

We present results of an experimental study of magnetoresistance (MR) in insulating NbSi amorphous alloys sample showing Variable Range Hopping (VRH) conductivity. The MR is found to be negative in a wide range of low temperature (4.2-20 K) and in the range of moderate magnetic fields (0-4 T). We made tentative analysis using three theoretical models which are the model of quantum interference, the model of Zeeman effect and the model of localized magnetic

关键词： NbSi Amorphous Alloys Negative Magnetoresistance Magnetic Field Localized Magnetic moments Quantum Interference

Positive Magnetoresistance in Hydrogenated Amorphous Alloys Silicon Nickel a-Si<sub>1-y</sub>Niy:H at Very Low Temperature with Magnetic Field

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Modern Physics 2012年第6期3卷 447-450页

作者： Abdelfattah Narjis Abdelhamid el kaaouachi Jamal Hemine Abdelghani Sybous Lhoussine Limouny Said Dlimi Rachid Abdia Gerard Buskipski Laboratoire de Physique de la Matière Condensée Département de Physique Faculté des Sciences et Techniques de Mohammadia Mohammedia Morocco Laboratoire de Spectroscopie Hertzienne LSH Université de LilleI Villeneuve d’Ascq Cedex France Research Group ESNPS Physics Department Faculty of Sciences University Ibn Zohr Agadir Morocco

We present results of an experimental study of magnetoresistance phenomenon in an amorphous silicon-nickel alloys a-Si1-yNiy:H:H (where y = 0.23) on the insulating side of the metal-insulator transition (MIT) in presence of magnetic field up to 4.5 T and at very low temperature. The electrical resistivity is found to follow the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T -1/2. This behaviour indicates the existence of the Coulomb gap (CG) near the Fermi level.

关键词： Amorphous Silicon-Nickel Alloys a-Si1-yNiy:H Variable Range Hopping Conductivity Metal Insulator Transition Positive Magnetoresistance

Variable Range Hopping in Hydrogenated Amorphous Silicon-Nickel Alloys

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Modern Physics 2012年第7期3卷 517-520页

作者： Abdelfattah Narjis Abdelhamid el kaaouachi Abdelghani Sybous Lhoussine Limouny Said Dlimi Abdessadek Aboudihab Jamal Hemine Rachid Abdia Gerard Biskupski Laboratoire de Physique de la Matière Condensée Faculté des Sciences et Techniques de Mohammadia Département de Physique Mohammedia Morocco Laboratoire de Spectroscopie Hertzienne LSH Batiment P5 Université des Sciences et Technologies de LilleI 59 655 Villeneuve d’Ascq Cedex France Research Group ESNPS Physics Department University Ibn Zohr Faculty of Sciences B.P 8106 Hay Dakhla 80000 Agadir Morocco

On the insulating side of the metal-insulator transition (MIT), the study of the effect of low Temperatures T on the electrical transport in amorphous silicon-nickel alloys a-Si1-yNiy:H exhibits that the electrical conductivity follows, at the beginning, the Efros-Shklovskii Variable Range Hopping regime (ES VRH) with T-1/2. This behaviour showed that long range electron-electron interaction reduces the Density Of State of carriers (DOS) at the Fermi level and creates the Coulomb gap (CG). For T higher than a critical value of temperature TC, we obtained the Mott Variable Range Hopping regime with T-1/4, indicating that the DOS becomes almost constant in the vicinity of the Fermi level. The critical temperature TC decreases with nickel content in the alloys.

关键词： Amorphous Silicon-Nickel Alloys a-Si1-yNiy:H Variable Range Hopping Conductivity Transport Phenomenon Metal Insulator Transition

A Comparison of the Performance of Various Estimators of Parametric Type1 Tobit Model

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Statistics 2013年第1期3卷 1-4页

作者： el Ouali Rahmani Abdelali kaaouachi Said el Melhaoui University of Mohammed first (EST) Oujda Morocco University of Mohammed first (FS) Oujda Morocco University of Mohammed first (FSJES) Oujda Morocco

In this paper, we use Monte Carlo simulations to compare parametric estimators of Type 1 Tobit model. In particular, we examine the performance for finite samples of three different estimators of simple Tobit model: the least squares (LS) estimator, the Heckman (H) estimator and the maximum likelihood (ML) estimator. These three estimators are consistent and asymptotically normal in the case where the density error is specified. However, these properties are sensitive to the situation where the error distribution is not specified. The purpose of this article is to determine properties of the three estimators, namely bias and convergence, by using Monte Carlo simulations.

关键词： Type 1 Tobit Model Parametric Estimation Monte Carlo Simulation