Spin-Orbit Readout Using Thin Films of Topological Insulator Sb2Te3 Deposited by Industrial Magnetron Sputtering

Driving a spin-logic circuit requires the production of a large output signal by spin-charge interconversion in spin-orbit readout devices. This should be possible by using topological insulators, which are known for their high spin-charge interconversion efficiency. However, high-quality topological insulators have so far only been obtained on a small scale, or with large scale deposition techniques that are not compatible with conventional industrial deposition processes. The nanopatterning and electrical spin injection into these materials have also proven difficult due to their fragile structure and low spin conductance. The fabrication of a spin-orbit readout device from the topological insulator Sb₂Te₃ deposited by large-scale industrial magnetron sputtering on SiO₂ is presented. Despite a modification of the Sb₂Te₃ layer structural properties during the device nanofabrication, a sizeable output voltage is measured that can be unambiguously ascribed to a spin-charge interconversion process. The results pave the way for the integration of layered van der Waals materials in spin-logic devices.     

Automatic calibration of Hall sensor microsystems

In many applications, a Hall element is used for contact-less measurement such as linear and angular positions, electrical current, power and energy, etc. The Hall element fabricated by means of CMOS technology features mediocre characteristics [R.S. Popovic, Z. Randjelovic, D. Manic, Integrated Hall-Effect Magnetic Sensors, EMSA, Germany, 2000; R.S. Popovic, Hall Effect Devices, Adam Hilger, Bristol, Philadelphia, New York, 1991]. It gives a weak output signal of the order of a few mV. This signal is often corrupted by sensor offset, noise, temperature and aging drift. This paper deals with the state of the art and main techniques capable to detect and compensate these issues. Case studies using mentioned techniques are also summarized.     

Utilization of the Antiferromagnetic IrMn Electrode in Spin Thermoelectric Devices and Their Beneficial Hybrid for Thermopiles

The thermoelectric effect in various magnetic systems, in which electric voltage is generated by a spin current, has attracted much interest owing to its potential applications in energy harvesting, but its power generation capability has to be improved further for actual applications. In this study, the first instance of the formation of a spin thermopile via a simplified and straightforward method which utilizes two distinct characteristics of antiferromagnetic IrMn is reported: the inverse spin Hall effect and the exchange bias. The former allows the IrMn efficiently to convert the thermally induced spin current into a measurable voltage, and the latter can be used to control the spin direction of adjacent ferromagnetic materials. It is observed that a thermoelectric signal is successfully amplified in spin thermopiles with exchange‐biased IrMn/CoFeB structures, where an alternating magnetic alignment is formed using the IrMn thickness dependence of the exchange bias. The scalable signal on a number of thermopiles allowing a large‐area application paves the way toward the development of practical spin thermoelectric devices. A detailed model analysis is also provided for a quantitative understanding of the thermoelectric voltages, which consist of the spin Seebeck and anomalous Nernst contributions.     

GeTe中铁电极化对自旋霍尔电导的调控研究

利用电场控制电荷的自旋流与电流相互转换是自旋电子器件的关键所在,而这种控制机制在铁电半导体GeTe中可以得到实现,因为其铁电极化可以改变自身的自旋织构。基于密度泛函理论计算,我们发现可以通过铁电极化可以进一步调节自旋霍尔电导(spinHallconductivity,简记为SHC),通过计算得到自旋霍尔电导的一个分量σxyz在带边缘附近可以达到100?/e(?cm)-1的量级,其主要原因在于电极化改变了能带结构。该研究工作为可控的自旋输运的实验和理论研究具有重要的价值,必将推动自旋电子学的进一步发展。     

基于霍尔效应开关的低功耗电源控制系统

电源控制系统是便携式电池供电设备的重要组成部分。对于户外一次性密封设备而言,电源控制系统何时启动是不确定的,通常采用传统的磁控干簧管开关来控制。然而,干簧管开关存在的机械反弹和接触寿命短暂等问题直接影响着设备的正常工作及使用寿命。基于CMOS技术的非接触式＂固态＂霍尔效应开关能显著地提高设备的可靠性。文中以电源管理芯片TPS62111和微功耗霍尔效应开关MLX90248为例,设计了一套微功耗电源控制系统,在保证设备可靠性的同时,尽可能地降低了设备的整体功耗,并在实际监测设备中得到了应用。     

基于大模面积掺Yb光纤的100W种子光主振荡器功率放大技术

演示了一种基于大模面积掺Yb3+离子的全光纤放大器系统,该系统采用975 nm泵浦。系统是利用泵浦与Yb3+离子有源光纤相互作用产生信号源,光源为半导体激光放大的单频种子。通过优化系统,合理设计搭建光学器件,控制光束逆传输,减少非线性光学的干扰。100 W信号源作用于系统上,采用多级掺镱光放大的主振荡器功率放大器（MOPA）,最大输出3.2 kW连续激光。平均光-光转化效率为78.26%。光束质量Mx21.657,My21.735。输出稳定性小于2%。系统连续信号放大输出光具有广泛的应用范围。掺Yb3+离子的全光纤放大主要用于激光检测、工业测量技术研究等领域。     

Electromagnetically compatible CMOS auto-balanced current sensor for highly integrated power control System-On-Chip

This paper describes the design and prototyping of an auto-balanced contactless current sensor in standard Complementary Metal–Oxide–Semiconductor (CMOS) technology, without any additional post-processing cost. The architecture includes two high-sensitivity Hall plates with differential amplification electronics. A high common mode rejection is insured by the integrated auto-balancing system based on the use of integrated coils. When a common current is applied in the embedded coils, the integrated system provides a feedback signal to a digital control unit which in turn adjusts the biasing current of one of the Hall plates in order to balance the amplification of the two Hall plates. Designed in a standard CMOS technology, this sensor can be integrated in power control System-On-Chip requiring extremely electro-magnetically compatible current sensor.     

FD SOI Hall sensor electronics interfaces for energy measurement

This paper presents a SOI Hall sensor based microsystem for energy measurement. The mixed-mode signal circuitry has been entirely designed and integrated in the experimental 0.5 μm fully depleted SOI 3 V technology. It consists of an integrated Hall element, chopper stabilized sensor bias system, analog front end and digital back end. Aiming at performing accurate measurements, we have implemented a high linearity analog front end, as well as a high-resolution analog-to-digital conversion technique. Two versions of the microsystem have been realized. The first test chip contains a classical instrumentation amplifier as sensor amplifier, whereas the second one contains a linearized differential-difference amplifier as sensor amplifier. Both microsystems are fully functional and permits one to perform the measurements with an overall system error that is less than ±1.5%.     

Thin wire hall effect devices

A thin wire inside a bulk semiconductor can concentrate the current density and the magnetic field strength to intensities that are significant for the Hall effect. Also, the self-magnetic field of the Hall currents can add to this intensification, particularly when there is axial symmetry and a toroidal configuration. The impedanceZiacross the ends of the wire is modified if a currentIflows between the semiconductor and the wire:|Zi| simeq omega / sigma . K_{H}. I[(b/a)^{k} -1]wherek = micro .sigma . K_{H}.I/(2.pi)andaandbare the inner and outer radii of a cylinder. A more complete analysis of the cylindrical field problem reveals that well-known results for skin effect are also modified by the current. The new solution is expressed by high-order Thompson functions, which include the ber and bei functions of skin effect as a special case. For values ofkgreater than 2, the solution can have a negative real wave impedance. Experiments are described for estimating changes in the Hall currents by counting flux jumps in a superconducting wire which is embedded in bulk bismuth. The Hall currents are magnified by the factor 5. In the course of the experiments, a pulse position modulator is realized. Other possible devices are realizable, notably an amplifier and a simple, rugged flip-flop.     

A Tunable Pseudo-Differential OTA With $-78~{hbox {dB}}$ THD Consuming 1.25 mW

A novel linear tunable transconductor based on a combination of linearization techniques is presented. The input signal is transferred to the V-I conversion element by means of a high-speed feedback loop. Then, the linear V-I conversion is accomplished using quasi-floating-gate MOS transistors biased in the triode region. Finally, the absence of current mirrors in the signal path provides low sensitivity to transistor mismatch and reduces the harmonic distortion. The operational transconductance amplifier (OTA) was fabricated in a 0.5-mum CMOS technology with a single 3.3-V supply voltage. Experimental results show a total harmonic distortion of -78 dB at 1 MHz with 1-V_pp input signal. High linearity of the OTA is obtained over a two octave tuning range with only 1.25-mW power consumption.     

An improved compact model for CMOS cross-shaped Hall-effect sensor including offset and temperature effects

A compact model of a cross-shaped horizontal integrated Hall-effect sensor is presented in this paper. Compared to existing models, reliability is improved, especially to simulate systems in which biasing and measurement circuits are not independent. The Hall device model core, already published, is based on a network of six non-linear resistances and four Hall voltage sources, and includes only 11 physical parameters. In this paper, in order to improve model predictivity, four additional parameters have been added to take the offset issue into account. In addition, variations of parameters with temperature are also addressed. The model is implemented in Verilog-A and has been validated through experiments carried out on Hall devices designed in a CMOS 0.35??m technology. The parameters extraction procedure is detailed and the maximum error between simulations and experimental data is less than 1?% for a wide range of biasing currents and temperatures.     

Integrated semiconductor magnetic field sensors

A magnetic field sensor is an entrance transducer that converts a magnetic field into an electronic signal. Semiconductor magnetic field sensors exploit the galvanomagnetic effects due to the Lorentz force on charge carriers. Integrated semiconductor, notably silicon, magnetic field sensors, are manufactured using integrated circuit technologies. Integrated sensors are being increasingly developed for a variety of applications in view of the advantage offered by the integration of the magnetic field sensitive element together with support and signal processing circuitry on the same semiconductor chip. The ultimate goal is to develop a broad range of inexpensive batch-fabricated high-performance sensors interfaced with the rapidly proliferating microprocessor. This review aims at the recent progress in integrated silicon magnetic devices such as integrated Hall plates, magnetic field-effect transistors, vertical and lateral bipolar magnetotransistors, magnetodiodes, and current-domain magnetometers. The current development of integrated magnetic field sensors based on III-V semiconductors is described as well. Bulk Hall-effect devices are also reviewed and serve to define terms of performance reference. Magnetic device modeling and the incorporation of magnetic devices into an integrated circuit offering in situ amplification and compensation of offset and temperature effects are further topics of this paper. Silicon will continue to be aggressively exploited in a variety of magnetic (and other) sensor applications, complementary to its traditional role as integrated circuit material.     

In-situ mobility profiling of GaAs MESFET's using the hall current technique

A novel experimental technique to perform in-situ Hall effect mobility profiling of short-channel devices is described in this paper. This is based on the measurement of the Hall current in the conduction channel of a transistor with a split source or drain contact. The mobility is then determined by a simple expression relating the Hall current, the physical dimensions of the channel, the total current injected in the device, and the magnetic induction. No special structure is required and the measurements can be performed on the usual MESFET or MODFET geometries. The same technique can also be used with devices fabricated on lower mobility materials such as silicon where the geometrical magnetoresistance measurements are not practical. Using the new technique, we have obtained spatial Hall mobility profiles in commercially available GaAs MESFET's. Our experimental results are in good agreement with data obtained by other researchers using magnetoresistance measurements. Finally, some theoretical and practical problems associated with our technique are discussed.     

4 W/mm蓝宝石衬底AlGaN/GaN HEMT

报道了利用南京电子器件研究所生长的蓝宝石衬底AlGaN/GaN异质结材料制作的HEMT,器件功率输出密度达4W/mm。通过材料结构及生长条件的优化,利用MOCVD技术获得了二维电子气(2DEG)面密度为0.97×1013cm-2、迁移率为1000cm2/Vs的AlGaN/GaN异质结构材料,用此材料完成了栅长1μm、栅宽200μm AlGaN/GaN HEMT器件的研制。小信号测试表明器件的fT为17GHz、最高振荡频率fmax为40GHz;负载牵引测试得到2GHz下器件的饱和输出功率密度为4.04W/mm。     

Quantum-Dot Semiconductor Mode-Locked Lasers and Amplifiers at 40 GHz

Mode-locked lasers (MLLs) and semiconductor optical amplifiers (SOAs) based on quantum-dot (QD) gain material will impact the development of next-generation networks, such as the 100 Gb/s Ethernet. MLLs presently consisting of a monolithic two-section device already generate picosecond pulse trains at 40 GHz. Temperature dependence of pulsewidth for p-doped devices, a detailed chirp analysis that is a prerequisite for optical time-division multiplexing applications, and data transmission experiments are presented in this paper. QD SOAs show superior performance for linear amplification as well as nonlinear signal processing. Using cross-gain modulation for wavelength conversion, QD SOAs are shown to have a small signal bandwidth beyond 40 GHz under high-bias current injection. This makes QD SOAs much superior to conventional SOAs.      

一种新颖的OTA结构的数模转换器

介绍了一种新颖结构的数模转换器，此转换器的设计核心是采用跨导运算技术，由CMOS运算跨导放大器（OTA）构成。此D／A转换器以模拟电流作为主要信号变量，以跨导运算放大器取代电压运算放大器，以基于OTA的有源元件取代部分无源元件，通过改变OTA的偏置电流，从而改变其互导增益gm和电压放大器增益Au，更适合于IC的集成。采用9个OTA构成一个8位的加法电路，8个OTA的互导增益gm对应8位的数字信号，8个MOS管作为开关运用由8位的数字信号控制，从而实现数字信号到模拟信号的转换。     

左心室转子多路测试与控制系统

在工业生产和科学技术研究的各行业中,常常利用PC或工控机对各种数据进行采集.数据采集技术是信息科学的重要分支,是传感器、信号获取、存储与处理等信息技术结合.左心室转子位移多路测试系统是一种由4个部分构成的系统,包括电涡流传感器多路数据采集,A/D转换,高速的处理芯片DSP,12864液晶显示,多路DA功率驱动.主要是通过电涡流传感器采集信号,利用A/D转换器采集人工心脏转子位移信号,再通过PID实现对系统的控制,并且将多路采集的数据在12864液晶显示屏上直观的显示出来.     

Novel vertical Hall cells in standard bipolar technology

Novel vertical Hall cells which detect the magnetic field parallel to the chip surface were developed using the standard bipolar technology. In the devices, an n+ buried layer makes a vertical current flow and introduces the sensitivity parallel to the chip surface. A sensitivity of 75 V/AT was measured.     

采用CMOS太赫兹波探测器的成像系统

太赫兹波成像技术在生物医疗和安全检测等领域具有广阔的应用前景。针对新一代信息技术对便携式太赫兹波成像设备的需求，设计了基于CMOS太赫兹波探测器的成像系统。该系统包括一款CMOS太赫兹波探测器、片外模数转换器（ADC）、FPGA数字信号处理器、二位步进机、四个抛物面镜和太赫兹波辐射源等。CMOS太赫兹波探测器集成了片上贴片天线以及作为检波元件的NMOS晶体管，探测器由180 nm标准CMOS工艺制成。太赫兹波探测器的输出被片外模数转换器（ADC）采集并转换为数字信号，该数字信号被FPGA采集并传输到电脑上成像。所有上述元件均被装备在印刷线路板（PCB）上以减小系统体积。该系统实现了透射式太赫兹波扫描成像而无需斩波-锁相技术，并给出在860 GHz的太赫兹波照射下隐藏在信封内部金属的成像结果。     

High Curie Temperature Ferromagnetism and High Hole Mobility in Tensile Strained Mn‐Doped SiGe Thin Films

Diluted magnetic semiconductors based on group‐IV materials are desirable for spintronic devices compatible with current silicon technology. In this work, amorphous Mn‐doped SiGe thin films are first fabricated on Ge substrates by radio frequency magnetron sputtering and then crystallized by rapid thermal annealing (RTA). After the RTA, the samples become ferromagnetic semiconductors, in which the Curie temperature increases with increasing Mn doping concentration and reaches 280 K with 5% Mn concentration. The data suggest that the ferromagnetism comes from the hole‐mediated process and is enhanced by the tensile strain in the SiGe crystals. Meanwhile, the Hall effect measurement up to 33 T to eliminate the influence of anomalous Hall effect reveals that the hole mobility of the annealed samples is greatly enhanced and the maximal value is ≈1000 cm² V^?1 s^?1, owing to the tensile strain‐induced band structure modulation. The Mn‐doped SiGe thin films with high Curie temperature ferromagnetism and high hole mobility may provide a promising platform for semiconductor spintronics.