Ballistic Spin Hall Transistor Using a Heterostructure Channel and Its Application to Logic Devices

In a ballistic spin transport channel, spin Hall and Rashba effects are utilized to provide a gate-controlled spin Hall transistor. A ferromagnetic electrode and a spin Hall probe are employed for spin injection and detection, respectively, in a two-dimensional Rashba system. We utilize the spin current of which polarization direction is controlled by the gate electric field which determines the strength of the Rashba effective field. By observing the spin Hall voltage, spin injection and coherent spin precession are electrically monitored. From the original Datta–Das technique, we measure the channel conductance oscillation as the gate voltage is varied. When the magnetization orientation of the injector is reversed by 180°, the phase of the Datta–Das oscillation shifts by 180° as expected. Depending on the magnetization direction, the spin Hall transistor behaves as an n- or p-type transistor. Thus, we can implement the complementary transistors which are analogous to the conventional complementary metal oxide semiconductor transistors. Using the experimental data extracted from the spin Hall transistor, the logic operation is also presented.     

Influence of the nonequilibrium-carrier concentration on the hall voltage in a p-type semiconductor

The dependence of the Hall voltage on the external electric field in a p-type semiconductor sample placed in a weak magnetic field is investigated. It is shown that the Hall voltage depends nonlinearly on the electric field in a sample whose thickness is comparable to the diffusion length and surface-recombination velocity is rather small. The Hall-voltage sign is opposite to that in a bulk sample in a certain range of electricfield strengths. The theoretical model describes well the experimental data for a p-type Ge sample.     

Quantum Hall effect in a single-mode wire

The quantum Hall effect in a single-mode wire is studied for the first time. It is established that a well-expressed quantum Hall resistance for filling factors i=1 and 2 is observed in magnetic fields in which the magnetic length becomes less than the width of the wire. Breakdown of proportionality with respect to the magnetic field in the arrangement of the Hall quantization plateau and the dissipative conductivity minima is observed. Fiz. Tekh. Poluprovodn. 33, 1369–1371 (November 1999)     

Analysis of a circular Hall plate with equal finite contacts

The circular Hall plate with four equal finite line contacts, lying symmetrically in respect of two orthogonal axes, is considered. Analytical expressions for the Hall voltage and the Hall mobility in which the finiteness of the contacts and the magnetic field are taken into account, are obtained by applying Schwarz-Christoffel transformations. It is shown that the numerical calculations involved can be reduced to those of regular definite integrals. Furthermore, in the case of not too large contacts, a simple approximative formula has been derived for the product μ_HB of Hall mobility and magnetic induction. It is given in a form directly suited to practical applications.     

Hall effect study of p-type high resistivity layers on n-type silicon substrates

Analytical expressions for the longitudinal electric field and Hall voltage in p-type high resistivity Halltrons on silicon substrate with opposite conductivity are derived. The effect of Joule heating on the current and Hall voltage has been studied, taking into account the temperature dependence of carrier mobility. It is shown that for p-diffused high resistivity Halltrons on an n-silicon substrate, the theoretical and experimental results are in close agreement.     

Spin interference of holes in silicon nanosandwiches

Spin-dependent transport of holes is studied in silicon nanosandwiches on an n-Si (100) surface which are represented by ultranarrow p-Si quantum wells confined by δ-barriers heavily doped with boron. The measurement data of the longitudinal and Hall voltages as functions of the top gate voltage without an external magnetic field show the presence of edge conduction channels in the silicon nanosandwiches. An increase in the stabilized source-drain current within the range 0.25–5 nA subsequently exhibits the longitudinal conductance value 4e ²/h, caused by the contribution of the multiple Andreev reflection, the value 0.7(2e ²/h) corresponding to the known quantum conductance staircase feature, and displays Aharonov-Casher oscillations, which are indicative of the spin polarization of holes in the edge channels. In addition, at a low stabilized source-drain current, due to spin polarization, a nonzero Hall voltage is detected which is dependent on the top gate voltage; i. e., the quantum spin Hall effect is observed. The measured longitudinal I–V characteristics demonstrate Fiske steps and a negative differential resistance caused by the generation of electromagnetic radiation as a result of the Josephson effect. The results obtained are explained within a model of topological edge states which are a system of superconducting channels containing quantum point contacts transformable to single Josephson junctions at an increasing stabilized source-drain current.     

Silicon hall-effect power IC's for brushless motors

The offset voltage which appears at the Hall electrodes in the absence of a magnetic field depends strongly on the mechanical stress. In order to reduce the effects of stress on the offset voltage, special wafer process and packaging techniques have been devised. A Hall device with alangle 100 rangledirection of current flow in the     

差分霍尔效应加速度测量方法及其线性实验模拟

对磁场中对称结构的霍尔元件的输出特性进行研究,提出一种差分霍尔效应加速度测量方法。基于线性霍尔元件和圆柱形永磁体设计加速度测量模型,两个霍尔元件与磁体构成对称互补结构,以差分方式输出信号电压。建立加速度与输出电压的线性关系,实现以非接触的方式测量加速度。模型的对称互补式设计,减小了非线性因素对测量的影响,改善了输出线性度。差分式电压输出,能够抑制共模干扰和零点漂移,并提高了信号幅度。对模型进行线性模拟实验,实验结果符合理论结论。数据分析显示,测量方法具有较高灵敏度和线性度。     

Gate-field-induced carrier heating in Si MOSFET's

We have used Si MOSFET's to study the variation of the channel Hall mobility and noise temperature with the gate voltage. From the Hall mobility measurements, a new empirical expression is found to describe the mobility degradation with gate voltage over a wide range of transverse electric field. By measuring the thermal noise, it is found that the channel carriers appear to be heated by the gate electric field and that the excess noise temperature varies quadratically with gate field.     

Contribution of light holes to the Hall effect for the complex valence band in germanium and its dependence on doping level

A method is proposed and implemented for experimentally isolating the influence of light holes on the classical Hall effect for the complex valence band in p-Ge. In this method the contribution from light holes is successively eliminated by an applied magnetic field, and then the absolute values of the hole concentrations are calibrated in pairs of samples specially prepared using neutron transmutation doping. The increase in electron concentration as a result of neutron transmutation doping is measured for one of the samples (the reference), while the hole concentration is measured for the other sample. This gives calibration curves for the effective Hall factor in p-Ge, which can be used to precisely measure the hole concentration over the entire range of doping levels. The use of this method for investigating the hopping transport of charge carriers and metal-insulator transitions is illustrated. Fiz. Tekh. Poluprovodn. 32, 811–820 (July 1998)     

Contact size effects on the van der Pauw method for resistivity and Hall coefficient measurement

Effects on van der Pauw's resistivity and Hall coefficient measurement due to finite size contacts with selected shapes on a square sample were investigated. For the sheet resistivity measurement, correction factors for the apparent measured values at zero magnetic field were determined from both electrolytic tank experiments and computerized over-relaxation calculations. For the Hall coefficient, correction factors for the effect of voltage shorting due to current electrodes and for the effect of current shorting due to Hall electrodes were calculated (by use of a fast-convergent over-relaxation technique) through a range of Hall angle from tan θ = 0·1–0·5. The current shorting contribution to the correction factor at zero magnetic field was also closely estimated by use of an electrolytic tank. In the symmetrical structures studied the Hall errors introduced by the voltage and current electrodes were approximately equal. The study shows that contacts of appreciable size relative to that of the sample can be a good approximation to van der Pauw's infinitesimal contact. Thus, one can utilize the simplicity and other advantages of finite size ohmic contacts for these measurements in normal semiconductor materials evaulation and still obtain precise data by using the appropriate correction factors determined in this paper.     

开关型CMOS霍尔传感器的设计

利用CMOS工艺制作的霍尔传感器一般失调电压较大。为了抑制霍尔传感器的失调电压,文中提出一种正交耦合旋转电流技术,利用开关改变失调电压的极性,经过采样相加抑制霍尔元件的失调电压,同时利用相关双采样技术降低电路失调电压。采用Cadence工具对电路进行仿真验证,3.3 V的供电电压下,平均失调电压为550 μV。结果表明,电路有效降低了霍尔传感器的失调电压。     

On the effect of gate oxide thickness upon the hall mobility and other magneto-electrical characteristics in most structures

P-Channel silicon MOS Halltrons with a different thickness of the oxide under the gate are studied. The measurements are performed in steady-state conditions at room temperature and in a weak magnetic field. Some conclusions about the surface conductivity, Hall mobility and Hall coefficient of carriers in the channel are given. The magneto-electrical characteristics are presented as a function of space charge, surface potential and free charge at the surface of the semiconductor. An explanation of the decrease of the surface conductivity in the nonlinear part of the curve of surface conductivity vs gate voltage is proposed.     

Electron-phonon interaction and electron mobility in quantum-well type-II PbTe/PbS structures

Electron mobilities in PbTe layers were calculated, taking into account electron scattering by longitudinal polar optical phonons, for low-dimensional structures — multiple PbTe/PbS quantum wells, which are type-II structures. Comparison with the electron mobilities obtained from Hall coefficient and magnetoresistance investigations in undoped multiple PbTe/PbS quantum wells versus the magnetic field intensity showed good agreement between the computed and experimental results for these structures. Fiz. Tekh. Poluprovodn. 32, 739–742 (June 1998)     

Hall measurements of n-indium arsenide MBE-deposited layers: Relevance to device processing and applications

This paper addresses the observed difference between the measured and theoretically computed concentration, resistivity and mobility for an n-InAs sample. This difference is a problem for measurements made during InAs device processing. The current literature does not provide a sufficient explanation of the problem, which appears only at temperatures lower than ~100 K. Nevertheless, it limits the use of semiconductor devices in new applications. We have previously suggested that the responsibility for such behavior may lie with an element, which functions as a donor at low temperatures and as an acceptor at higher temperatures.Another problem arises from using Hall potential measurements to obtain the concentration, mobility and resistivity of intentionally undoped n-InAs MBE layers. The experimental data show a dependence of the obtained results on the magnetic field strength. The experimental data agree with the computational values only at 0.6 T in the range of ~100–300 K. The purpose of this paper is to show how to obtain proper results for the conduction parameters of InAs using Hall voltage measurements.     

Oxygen precipitates and the formation of thermal donors in silicon

It is established by infrared spectroscopy and Hall measurements that the oxygen precipitates formed during preliminary high-temperature treatment suppress the generation of thermal donors in Si grown either by the Czochralski method or by applying a magnetic field to a melt. Possible mechanisms for the influence of precipitation on the formation of thermal donors are proposed. Fiz. Tekh. Poluprovodn. 32, 712–713 (June 1998)     

Hall effect in a non homogeneous magnetic field

The purpose of this paper is to investigate the influence of a non homogenous magnetic field on the characteristics of a Hall generator. For a particular shape of the magnetic field strength the problem can be solved without further approximations by an integral equation technique. This offers the advantage that the problem can be analysed for extreme values of the non homogeneous component of the magnetic field. This fact is checked by means of the Hall voltage generated in a rectangular sample.     

High field transport in PbTe

The drift velocity and Hall coefficient of tn and p-type PbTe at 77K were measured for various crystallographic directions of current up to field strengths of 1.5 kV/cm. Both the conductivity and the Hall effect are anisotropic with the latter depending also strongly on the magnetic field. These effects are attributed to nonuniform heating of the equivalent conduction band L-valleys of PbTe and equivalent intervalley transfer. For field strengths beyond 1 kV/cm oscillations of the current and the potential distribution occur. The Hall coefficient decreases sharply above this threshold indicating avalanche breakdown. At still higher field strengths a sign reversal of the Hall coefficient is observed. Probing the potential distribution, it could be shown that this instability is caused by high field domains, which travel along the sample with the drift velocity of the carriers. Possible mechanisms for the formation of high field domains are discussed.     

Temperature Distribution in Two-Dimensional Electron Gases under a Strong Magnetic Field

Two-dimensional electron gases having an electrochemical potential gradient under a magnetic field are numerically examined using the finite-difference method. The temperature, voltage, electric current, and heat flux are calculated from transport equations describing thermoelectric and thermomagnetic effects, namely the Hall, Nernst, Ettingshausen, and Righi–Leduc effects. The results show that a magnetic field distorts equipotential lines and generates an uneven temperature distribution. In particular, a part of the system is found to become colder than the temperature of the heat baths. The cooling effect under a strong magnetic field is due primarily to the Ettingshausen and Hall effects.     

Short-range data link using a gallium arsenide lamp

The magnetic field near a current-carrying conductor generates a Hall voltage in a silicon specimen, which, in turn, controls the pulse-repetition frequency of a gallium arsenide lamp. The instrument is versatile and has a range of about 10 m.