Hall Effect In Semiconductors Research Articles

Повышение уровня качества образования усилением исследовательской составляющей обучения

The paper deals with the issues of improving the quality of education at the university. The role of the material and technical support of the educational process is emphasized. The possibilities of using the modern laboratory complex "Electricity and Magnetism" are shown when conducting educational research work of students in physics. The author gave an example of experimental research on the topic "Study of the Hall effect in semiconductors." The contribution of students' educational and research work to the formation of general professional competencies is noted.

Physical Investigations on Bias-Free, Photo-Induced Hall Sensors Based on Pt/GaAs and Pt/Si Schottky Junctions.

Hall-effect in semiconductors has wide applications for magnetic field sensing. Yet, a standard Hall sensor retains two problems: its linearity is affected by the non-uniformity of the current distribution; the sensitivity is bias-dependent, with linearity decreasing with increasing bias current. In order to improve the performance, we here propose a novel structure which realizes bias-free, photo-induced Hall sensors. The system consists of a semi-transparent metal Pt and a semiconductor Si or GaAs to form a Schottky contact. We systematically compared the photo-induced Schottky behaviors and Hall effects without net current flowing, depending on various magnetic fields, light intensities and wavelengths of Pt/GaAs and Pt/Si junctions. The electrical characteristics of the Schottky photo-diodes were fitted to obtain the barrier height as a function of light intensity. We show that the open-circuit Hall voltage of Pt/GaAs junction is orders of magnitude lower than that of Pt/Si, and the barrier height of GaAs is smaller. It should be attributed to the surface states in GaAs which block the carrier drifting. This work not only realizes the physical investigations of photo-induced Hall effects in Pt/GaAs and Pt/Si Schottky junctions, but also opens a new pathway for bias-free magnetic sensing with high linearity and sensitivity comparing to commercial Hall-sensors.

Preface

The 22nd Russian Youth Conference on Physics of Semiconductors and Nanostructures, Opto- and Nanoelectronics (RYCPS) was held in Saint Petersburg on November 23 – 27, 2020. It was organized by Peter the Great St. Petersburg Polytechnic University.The program of the Conference included semiconductor technology, heterostructures with quantum wells and quantum dots, opto- and nanoelectronic devices and new materials. Given the restrictions on meetings of a large number of people associated with COVID-19, the conference organizing committee decided to hold it in a virtual format. The oral sessions were held on the Zoom platform, and the poster session was organized using the Miro online whiteboard and the Skype platform. This provided an opportunity for valuable discussions between the conference participants and experienced scientists.The conference included two invited talks given by leading scientists, devoted to actual problems and major advances in physics and technology. The keynote speakers were Mikhail Nestoklon from Ioffe Institute (presentation “Fine structure of excitons in quantum dots based on Pb chalcogenides”) and Sergey Kukushkin from Institute of Problems of Mechanical Engineering (presentation “A new method of controlled synthesis of nanomaterials for micro- and optoelectronics. Thermodynamics and kinetics of nanoscale synthesis of single-crystal silicon carbide on silicon and its unique properties”). Students, graduate and postgraduate students presented their results on plenary and poster sessions. The total number of accepted papers published in Russian (the official conference language) was 105. Here we publish 24 of them in English.Like previous years, the participants were involved in the competition for the best report. Certificates and cash prizes were awarded to a number of participants for the presentations selected by the Program Committee. Aidar Galimov, a postgraduate student at Ioffe Institute (Saint Petersburg), received the E.F. Gross Prize for the best presentation in the field of semiconductor optics for the report “Investigation of the single photons indistinguishability in InAs/GaAs quantum dots”. Mikhail Rakitskii (Alferov University, Saint Petersburg) was awarded for the best presentation among students with a report “Anomalous Hall effect in semiconductors with zero spin polarization”. Ivan Makhov (Peter the Great St. Petersburg Polytechnic University) was awarded for the best presentation among postgraduate students with a report “Linear refractive index modulation induced by electric current in GaAs/AlGaAs quantum wells”. Works with potential applications were recommended for participation in the following competition for support from the Russian Foundation for Assistance to Small Innovative Enterprises in Science and Technology.The conference was supported by the Russian Foundation for Basic Research, the Ministry of Science and Higher Education of the Russian Federation (Program “5–100”) and Tydex LLC, St. Petersburg.The official conference website is http://www.semicond.ru/conf2020 Editors R.A. Suris L.E. Vorobjev D.A. Firsov V.A. Shalygin

Magnetic Field Sensor Based on Varistor Response

We present, in this paper, a non-conservative approach for building reliable magnetic field sensors based on the resistive and magnetoresistive responses of a varistor diode. These sensors can be built on a ceramic platform of a material which is a solid solution of the ilmenite–hematite consisting of 55 moles% ilmenite, FeTiO3, and 45 mole% of hematite, Fe2O3. This material is abbreviated as IHC 45. These sensors would be suitable for many applications in which a semiconductor Hall effect sensor is currently used. In addition, our ceramic sensors would be suitable for applications in high temperature, energy exploration and well logging, and radiation-dominant environments. The resistive mode sensor is expected to operate reliably and efficiently over the range of 0 $\text{m}\Omega $ /Oe at 0.5 mA which drops to a value of 24.2 $\text{m}\Omega $ /Oe at 2 mA. In the magnetoresistive mode, the sensor has the sensitivity of $142.6~\Omega $ /ln(Oe) and it is 15.6 $\text{m}\Omega $ /Oe at 2 mA. The magnetoresistive mode device also exhibits at room temperature a relatively large magnetoresistive ratio (MR%) of 57% at the modest field of just 4000 Oe making it potentially an attractive candidate for applications in spintronics and magneto-electronics.

Dynamics of weakly interacting bosons in optical lattices with flux

Realization of strong synthetic magnetic fields in driven optical lattices has enabled implementation of topological bands in cold-atom setups. A milestone has been reached by a recent measurement of a finite Chern number based on the dynamics of incoherent bosonic atoms. The measurements of the quantum Hall effect in semiconductors are related to the Chern-number measurement in a cold-atom setup, however, the design and complexity of the two types of measurements are quite different. Motivated by these recent developments, we investigate the dynamics of weakly interacting incoherent bosons in a two-dimensional driven optical lattice exposed to an external force, which provides a direct probe of the Chern number. We consider a realistic driving protocol in the regime of high driving frequency and focus on the role of weak repulsive interactions. We find that interactions lead to the redistribution of atoms over topological bands both through the conversion of interaction energy into kinetic energy during the expansion of the atomic cloud and due to an additional heating. Remarkably, we observe that the moderate atomic repulsion facilitates the measurement by flattening the distribution of atoms in the quasi-momentum space. Our results also show that weak interactions can suppress the contribution of some higher-order non-topological terms in favor of the topological part of the effective model.

A functional identity involving elliptic integrals

We show that the following double integral \[\int_{0}^\pi {\rm d}x \int_0^x {\rm d}y \frac{1}{\sqrt{1-\smash[b]{p}\cos x}\sqrt{1+\smash[b]{q\cos y}}}\]remains invariant as one trades the parameters $p$ and $q$ for $p'=\sqrt{1-p^2}$ and $q'=\sqrt{1-q^2}$ respectively. This invariance property is suggested from symmetry considerations in the operating characterstics of a semiconductor Hall-effect device.

Studying the effective of conductor polymer substrate on the electrical properties of semiconductors

This research includes depositionof thin film of semiconductor, CdSe by vaccum evaporation on conductor polymers substrate to the poly aniline where, the polymer deposition on the glass substrats by polymerization oxidation tests polymeric films and studied the structural and optical properties through it,s IR and UV-Vis , XRD addition to thin film CdSe, on of the glass substrate and on the substrate of polymer poly-aniline and when XRD tests was observed to improve the properties of synthetic tests as well as the semiconductor Hall effect proved to improve the electrical properties significantly

Studying the effective of conductor polymer substrate on the electrical properties of semiconductors

This research includes depositionof thin film of semiconductor, CdSe by vaccum evaporation on conductor polymers substrate to the poly aniline where, the polymer deposition on the glass substrats by polymerization oxidation tests polymeric films and studied the structural and optical properties through it,s IR and UV-Vis , XRD addition to thin film CdSe, on of the glass substrate and on the substrate of polymer poly-aniline and when XRD tests was observed to improve the properties of synthetic tests as well as the semiconductor Hall effect proved to improve the electrical properties significantly

Surface-adaptable all-metal micro-four-point probe with unique configuration

In this paper, we propose a surface-adaptable all-metal micro-four-point probe (μ4PP) with a unique configuration. The μ4PP consists of four independent metallic sub-cantilevers with sharp Cu tips, and an SU-8 body structure to support the sub-cantilevers. The tip height is approximately 15 μm, and the tips are fabricated by anisotropic wet-etching of silicon followed by Cu electroplating. Each metallic cantilever connected to the SU-8 body structure acts as a flexible spring, so that the conducting tip can make gentle, non-destructive contact with fragile surfaces. To enhance the adhesion between the metallic sub-cantilevers and the SU-8 body, mushroom-shaped Cu structures were fabricated using an under-baked and under-exposed photolithography process. Various μ4PPs were designed and fabricated to verify their diverse range of applications, and preliminary experiments were performed using these fabricated μ4PPs. The resultant flexibility and reliability were experimentally confirmed on several samples, such as a polymer cantilever, a graphene flake, and curved metallic surfaces. We also expect that the proposed μ4PP will be suitable for measuring the anisotropic characteristics of crystal materials or the Hall effect in semiconductors.

The influence of an MgO nanolayer on the planar Hall effect in NiFe films

The Planar Hall Effect (PHE) in NiFe films was studied using MgO as the buffer and capping layer to reduce the shunt effect. The thermal annealing was found to be effective in increasing the sensitivity. The sensitivity of the magnetic field reached as high as 865 V/AT in a MgO (3 nm)/NiFe (5 nm)/MgO(3 nm)/Ta(3 nm) structure after annealing at 500 °C for 2 h, which is close to the sensitivity of semiconductor Hall Effect (HE) sensors. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) were used to study the sample. The results show that the top crystallization of MgO and NiFe (111) texture were improved by proper annealing. The smooth and clear bottom MgO/NiFe and top NiFe/MgO interface is evident from our data. In addition, the shunt current of Ta was decreased. These combined factors facilitate the improvement of the sensitivity of the magnetic field.

Spin Force on Pseudo Spin Current in Graphene

The present study investigated spin force by using pseudo spin-orbit coupling in an artificial atomic structure for graphene. This spin force, which is applied on pseudo spin current, can be controlled by graphene gap and electric field due to charged nanodot. It seems that, by this force can be constructed a logical system from graphene and semiconductors. In addition, this force can be used for understanding the Zitterbewegung of electron wave packet with pseudo spin-orbit coupling in graphene and create of the charge Hall effect in semiconductors and graphene.

Optical detection of spin Hall effect in metals

Optical techniques have been widely used to probe the spin Hall effect in semiconductors. In metals, however, only electrical methods such as nonlocal spin valve transport, ferromagnetic resonance, or spin torque transfer experiments have been successful. These methods require complex processing techniques and measuring setups. We show here that the spin Hall effect can be observed in non-magnetic metals such as Pt and β-W, using a standard bench top magneto-optical Kerr system with very little sample preparation. Applying a square wave current and using Fourier analysis significantly improve our detection level. One can readily determine the angular dependence of the induced polarization on the bias current direction (very difficult to do with voltage detection), the orientation of the spin Hall induced polarization, and the sign of the spin Hall angle. This optical approach is free from the complications of various resistive effects, which can compromise voltage measurements. This opens up the study of spin Hall effect in metals to a variety of spin dynamic and spatial imaging experiments.

All‐electrical detection of spin Hall effect in semiconductors

Since the prediction of the spin Hall effect more than 40 years ago, significant progress was made in theoretical description as well as in experimental observation, especially in the last decade. In this article, we present three different concepts and measurement geometries for all‐electrical detection of the direct and the inverse spin Hall effect in semiconductors. Based on experiments with n‐ and p‐doped GaAs microstructures, we describe our experimental approaches and methods to experimentally identify the spin Hall effect and compare our results to previous experiments and theoretical considerations. Device geometry for the detection of the direct spin Hall effect.

Modelling and optimization of submicron Hall sensors for the detection of superparamagnetic beads

This paper deals with the numerical modeling of the electric potential distribution inside semiconductor Hall effect devices, under the presence of non-uniform magnetic fields. The model is applied to study miniaturized sensors for the detection of superparamagnetic nanobeads. The magnetic moment resolution is evaluated for different Hall probe geometries, by varying the bead size and its distance from the sensor surface.

Optically induced Hall effect in semiconductors

We describe an experiment which investigates the effect of a longitudinal electric field on the spin-polarized carriers generated by a circularly polarized light in semiconductors. Our experiment observes the effect as a Hall voltage resulting from nonequilibrium magnetization induced by the spin-carrier electrons accumulating at the transverse boundaries of the sample as a result of asymmetries in scattering for spin-up and spin-down electrons in the presence of spin-orbit interaction. It is found that the effect depends on the longitudinal electric field and doping density as well as on temperature. The results are presented by discussing the dominant spin relaxation mechanisms in semiconductors.

Berry curvature in graphene: a new approach

In the present paper we have directly computed the Berry curvature terms relevant for graphene in the presence of an inhomogeneous lattice distortion. We have employed the generalized Foldy–Wouthuysen framework, developed by some of us. We show that a non-constant lattice distortion leads to a valley–orbit coupling which is responsible for a valley–Hall effect. This is similar to the valley–Hall effect induced by an electric field proposed in the literature and is the analogue of the spin–Hall effect in semiconductors. Our general expressions for Berry curvature, for the special case of homogeneous distortion, reduce to the previously obtained results. We also discuss the Berry phase in the quantization of cyclotron motion.

Effects of irradiation with gamma and beta rays on semiconductor Hall effect devices

The effects of short duration irradiation with low dose rate gamma and beta rays on the input resistance and the output Hall voltage of InSb, GaAs, Si, and Ge semiconductor Hall effect devices were systemically studied. Both gamma and beta irradiation can cause the input resistance of Hall effect devices to increase linearly with increasing irradiation time, in the absence of a magnetic field. When the devices were placed in a magnetic field, the output Hall voltage and input resistance increased nonlinearly with increasing gamma irradiation time. The effects of both gamma and beta irradiation persisted long after the irradiation itself, and without annealing. The effects from irradiation in Hall effect devices can be mainly ascribed to the degradation of the charge carriers’ transport properties caused by radiation-induced defects. The radiation resistance of the Hall effect devices was estimated by considering changes of the input resistance under the same irradiation conditions. The Ge and Si Hall effect devices demonstrated a better radiation resistance than the InSb and GaAs Hall effect devices due to their large displacement threshold energy.

ADIABATIC PROCESS AND CHERN NUMBERS

We study quantum processes with two or more adiabatic parameters. When the parameters are compactified, a derivative of the Hamiltonian is closely related to a first Chern number. This topological formulation is applied to the AC Josephson effect and the spin Hall effect in semiconductors.

Quantum Hall effect in graphene: Emergent modular symmetry and the semicircle law

Low-energy transport measurements in quantum Hall systems have been argued to be governed by emergent modular symmetries whose predictions are robust against many of the detailed microscopic dynamics. We propose the recently observed quantum Hall effect in graphene as a test of these ideas, and identify to this end a class of predictions for graphene which would follow from the same modular arguments. We are led to a suite of predictions for high-mobility samples that differs from those obtained for the conventional quantum Hall effect in semiconductors, including predictions for the locations of the quantum Hall plateaus, predictions for the positions of critical points on transitions between plateaus, a selection rule for which plateaus can be connected by low-temperature transitions and a semicircle law for conductivities traversed during these transitions. Many of these predictions appear to provide a good description of graphene measurements performed with intermediate-strength magnetic fields.

Light-induced Hall effect in semiconductors with spin-orbit coupling

We show that optically excited electrons by a circularly polarized light in a semiconductor with spin-orbit coupling subject to a weak electric field will carry a Hall current transverse to the electric field. This light-induced Hall effect is a special type of anomalous Hall effect and is a result of quantum interference of the light and the electric field and can be viewed as a physical consequence of the spin current induced by the electric field. The light-induced Hall conductivity is calculated for the $p$-type GaAs bulk material and the $n$-type and $p$-type quantum well structures.