基于共振光隧穿效应的加速度传感器

为了设计新型的加速度传感器，将共振光隧穿结构应用于传感元件，利用COMSOL软件对传感器的频率响应、灵敏度性能等关键要素进行了模拟仿真分析，搭建了实验平台，验证了共振光隧穿原理。结果表明，基于共振光隧穿效应结构的加速传感器在100Hz~3000Hz范围内、加速度为500m/s2的情况下，灵敏度可达到6.7dB/g。该传感器小巧轻便、结构简单，且具有较高的灵敏度，这为光学传感器的研究提供了新的方法和思路，具有广阔的应用前景。     

An exclusive-nor based on resonant interband tunneling FET's

We have proposed and demonstrated an XNOR device based on the negative differential resistance in a resonant interband tunneling diode and the current control capabilities of field effect transistors. DC and timing measurements have confirmed the operations of the device. Simulations and discussions will be presented     

Design of nanopipelined adder based on resonant tunneling diode

Due to the negative differential resistance exhibited by resonant tunneling diode (RTD), RTD is suited to implement the threshold gates and increases the functionality of a single gate. Recently, multi-threshold threshold gates (MTTGs) and generalized threshold gates (GTGs) have been proposed, which extend the circuit applications of RTDs. In this paper, a new RTD full adder structure with three logic modules is proposed. Based on this structure, four different adders are built with the combination of different module circuits based on MTTG and GTG. From the simulation results, one of the proposed circuits with GTG structure, namely FA_GG, has the best performance, which reduces 27.7–45.9% power-delay product value in comparison with the previous designs.     

Multibit resonant tunneling diode SRAM cell based on slew-rateaddressing

We propose and demonstrate a resonant-tunneling diode (RTD) based memory cell in which N bits are stored in a series combination of N RTDs without internal node contacts. The slew rate of an applied voltage signal determines the circuit switching dynamics and allows addressing of the bits. We verify slew rate dependent switching order of up to four series RTDs experimentally and through SPICE simulation incorporating a physics-based RTD model. The new addressing scheme allows N bits to be stored in a stack of N vertically integrated RTDs compared to log₂ (N) bits in previous demonstrations. We demonstrate a two-bit two-RTD static memory cell based on the new method     

A multiple-state memory cell based on the resonant tunneling diode

The device consists primarily of several molecular-beam-epitaxy (MBE-) grown GaAs/(AlGa)As resonant tunneling diodes connected in parallel. This device exhibits multiple peaks in the I-V characteristic. When a load resistor is connected, the circuit can be operated in a multiple stable mode. With this concept, implementation of three-state and four-state memory cells are made. In the three-state case the operating points at voltages V₀=0.27 V , V₁=0.42 V, and V₂=0.53 V represent the logic levels 0, 1, and 2. Similarly for the four-state memory cell the logic levels voltages are V₀=0.35 V, V₁=0.42 V, V₂=0.54 V, and V ₃=0.59 V. A suggestion of an integrated device structure using this concept is also presented     

QDRTD单光子探测技术

量子信息技术的发展对单光子探测器提出了更高的性能要求,新型的量子点单光子探测器展现出了很好的性能和发展潜力。研究了一种基于量子点共振隧道二极管(QDRTD)的单光子探测器,介绍了QDRTD的基本结构和原理,重点对其内部电子传输特性和I-V特性进行了分析,并进行了结构优化,可满足单光子探测中多种波长选择的需求,为QDRTD多波长单光子探测的光子响应特性、探测效能等研究奠定了基础。同时,分析结果表明:QDRTD单光子探测器在光子响应、暗电流、波长选择等多个方面都具备很好的特性,具有广阔的应用前景。     

Waveguide slot radiator feeding a parallel plate polarizer

Slotted waveguide linear arrays are quite commonly enclosed in a parallel plate structure, to suppress cross-polar lobes in the case of inclined-slot arrays, and to suppress wide angle grating lobes in the case of shunt slot arrays. However, design equations for such arrays generally assume that the slots radiate into a half space and consequently for arrays designed on this basis significant pattern degradation can occur when the parallel plate structure is introduced. By imaging the slot in the enclosing parallel conducting planes it is shown that the conventional half-space analysis can be enlarged to accommodate the presence of a parallel plate polarizer with very little difficulty, since no more than about ten images are required to model a typical geometry.     

Proposal of an optical modulator based on resonant tunneling andintersubband transitions

We propose and analyze an optical modulator based on intersubband transitions. The absorption is modulated by modulating the carrier density in the ground state of a quantum well (QW). Electrons are injected resonantly into this subband from a QW reservoir subband through a single barrier. When the two states are tuned out of resonance, the electrons are rapidly evacuated by means of the optical field. A waveguide based on surface plasmons is assumed in order to have a high optical mode overlap. Calculations are performed for a cascaded structure with four periods, assuming InGaAs-InIAs QWs. The considered modulator structure operates at λ=6.0 μm and is RC limited to 27 GHz. An extinction ratio of 4 is obtained with a low applied voltage of 0.6 V. At larger applied voltages, the absorption is bistable. Absorption at shorter/longer wavelengths can be obtained by using materials with a larger/smaller conduction band offset. We also assess resonant tunneling from a 2-D electron gas reservoir into an array of quantum dots and compare it to the 2-D-2-D tunneling resonance     

谐振式隧穿磁强计的理论研究

分析了隧道扫描显微镜和隧穿磁强计的区别 ,认为隧穿磁强计的隧尖不需要也不应该过尖。研究了隧道间隙和隧道电流的关系。研究表明 ,虽然按照隧道效应理论 ,隧道间隙和隧道电流应该成指数关系 ,但对隧穿磁强计而言 ,其隧道电流和隧道间隙的关系可以近似看作线性关系。推导了谐振式隧穿磁强计的灵敏度计算公式     

谐振式隧穿磁强计的理论研究

分析了隧道扫描显微镜和隧穿磁强计的区别，认为隧穿磁强计的隧尖不需要也不应该过尖。研究了隧道间隙和隧道电流的关系。研究表明，虽然按照隧道效应理论，隧道间隙和隧道电流应该成指数关系，但对隧穿磁强计而言，其隧道电流和隧道间隙的关系可以近似看作线性关系。推导了谐振式隧穿磁强计的灵敏度计算公式。     

InP-base resonant tunneling diodes

We have fabricated Ino.53Ga0.47As/AlAs/InP resonant tunneling diodes (RTDs) based on the air-bridge technology by using electron beam lithography processing. The epitaxial layers of the RTD were grown on semiinsulating (100) InP substrates by molecular beam epitaxy. RTDs with a peak current density of 24.6 kA/cm2 and a peak-to-valley current ratio of 8.6 at room temperature have been demonstrated.     

InP基共振遂穿二极管器件（RTD）研究

我们在实验中对InGaAs/AlAs/InP共振遂穿二极管（RTD）材料结构进行了优化设计,并用MBE设备在(100)半绝缘InP单晶片上生长了RTD外延材料。我们采用电子束光刻工艺和空气桥互连技术,制作了InP基RTD器件。并在室温下测试了器件的电学特性：峰值电流密度24.6kA/cm2,峰谷电流比(PVCR)为8.6。     

Waveguide with resonant array inserts

The concept of guiding waves using passive arrays as frequency dependent walls is outlined. A prototype waveguide structure with arrays of tripoles as inserts has been built and used to demonstrate the wave guiding phenomenon.<>     

基于共振隧穿理论的GaAs基RTD的设计与研制

以共振能级的透射系数半峰宽(FWHM)做为共振隧穿二极管(RTD)材料结构设计的依据,对GaAs/AlAs/In0.1Ga0.9As材料体系的RTD进行了设计.用分子束外延(MBE)进行了RTD结构材料制备,X射线双晶衍射(XRD)分析表明,制备的异质结界面光滑、层厚准确.RTD采用台面结构,器件特性测试结果表明,峰值...     

Nine-state resonant tunneling diode memory

The authors demonstrate an epitaxial series combination of eight pseudomorphic AlAs/In_0.53Ga_0.47As/InAs resonant tunneling diodes (RTDs) grown by molecular beam epitaxy on InP. This series RTD produces an eight-peak multiple negative differential resistance characteristic with a peak-to-valley current ratio (PVR) exceeding 2 per peak at a peak current density of approximately 6 kA/cm ². Hysteresis in the current-voltage characteristic is reduced by uniformly Si doping the double-barrier resonant tunneling region at a density of 5×10¹⁶ cm^-3. Using this multiple-peak RTD in series with a field-effect transistor load, a nine-state multivalued memory circuit is demonstrated     

Double-barrier resonant tunneling transport model

A semiquantum transport model for electron transport in the resonant tunneling diode (RTD) is presented. The total electrons tunneling through the RTD are partitioned into two parts. The first is the coherent tunneling electrons, which do not experience any scattering except by the barriers during tunneling. These electrons are described by the damped resonant tunneling model. The second is the incoherent tunneling electrons, which are the electrons scattered in the quantum well by the phonons, impurities, etc. The hot electron distribution, which is characterized by the effective Fermi energy μ_e and electron temperature T_e, is proposed to model the nonequilibrium distribution of the incoherent electrons in the well. The parameters μ_e and T_e can be uniquely determined by applying the energy conservation law and the particle conservation law to the incoherent electrons in the well. The incoherent electrons play a major role in the operation of the RTD. The capacitance of the RTD is investigated, based on the model and Poisson's equation. Extensive numerical results are presented     

Improving the peak current density of resonant tunneling diode based on InP substrate

Resonant tunneling diodes (RTD) have the potential for compact and coherent terahertz (THz) sources operating at room temperature, but their low output power severely restricts their application in THz frequency range. In this paper, two methods are adopted to increase the peak current of RTD for enhancing its output power. First, different metal contact systems (including Pt/Ti/Pt/Au and AuGe/Ni/Au) for RTD contact are introduced, and a higher current of RTD with Pt/Ti/Pt/Au contact demonstrates the superior contact characteristic of Pt/Ti/Pt/Au contact system. Second, the double barrier structure (DBS) of RTD is well designed to further improve the characteristic of RTD, and a high peak current of 154 kA/cm² is achieved at room temperature. The improved peak current is very beneficial for increasing the output power of RTD oscillator.     

Analysis of metal-clad anti resonant reflecting optical waveguidefor polarizer applications

The dispersion and attenuation characteristics of an ARROW (antiresonant reflecting optical waveguide) with and without thin metal layers deposited on the outside of the interference cladding layer are investigated. These thin metal layers improve the polarization-selective performance of the ARROW considerably. A simple analytical expression to calculate the optimal thickness of the metal layer is derived     

Rashba effect resonant tunneling spin filters

We propose an InAs/GaSb/AlSb-based asymmetric resonant interband tunneling diode (a-RITD) as a spin filter. The device exploits the Rashba effect to achieve spin polarization under zero magnetic field using nonmagnetic III-V semiconductor heterostructures. We discuss the basic principles of the interband tunneling spin filter, and present modeling results that demonstrate its advantage. We also propose an implementation procedure for realizing device structure.