High-speed large-area inverted InGaAs thin-film metal-semiconductor-metal photodetectors

Inverted metal-semiconductor-metal (I-MSM) photodetectors, which are thin-film MSMs with the growth substrate removed and fingers on the bottom of the device (to eliminate finger shadowing to enhance responsivity), are reported herein for high-speed high-efficiency large-area photodetectors. Reported herein are the highest speed vertically addressed large-area (40-/spl mu/m diameter) photodetectors reported to date, which operate with a responsivity of 0.16 A/W and a full-width half-maximum of less than 5 ps. Materials, fabrication processes, heterogeneous integration, and characterization of I-MSM photodetectors are presented in this paper, as measured using a fiber-based electrooptic sampling system. These large-area photodetectors are ideal for vertically addressed high-speed optical links which need alignment-tolerant packaging for cost sensitive applications.     

GaAsSb: a novel material for near infrared photodetectors on GaAs substrates

We have studied the molecular beam epitaxy (MBE) growth of GaAsSb on GaAs substrates. The optical properties and composition of GaAsSb layer strongly depend on the growth temperature, the Ga growth rate, and the As and Sb fluxes and their ratios. We also report on two GaAsSb-GaAs photodiode structures operating at 1.3 /spl mu/m. The peak quantum efficiency was 54% for the GaAsSb resonant-cavity-enhanced (RCE) p-i-n photodiode and 36% for the RCE GaAsSb avalanche photodiode (APD) with separate absorption, charge, and multiplication regions (SACM). At 90% of the breakdown, the dark current of the SACM APD was 5 nA. The GaAsSb SACM APD also exhibited very low multiplication noise and k/sub eff/ was approximately 0.1, which is the lowest ever reported for APDs operating at 1.3 /spl mu/m.     

Optimization of GaAs amplification photodetectors for 700% quantum efficiency

We investigate the device physics of novel GaAs waveguide photodetectors with integrated photon multiplication. Such detectors have the potential to achieve simultaneously high saturation power, high speed, high responsivity, and quantum efficiencies above 100%. Our device design vertically combines a bulk photodetector ridge waveguide region with laterally confined quantum wells for amplification. Measurements on the first device generation show quantum efficiencies of only 56%. Advanced device simulation is employed to analyze these devices and to reveal performance limitations. Excellent agreement between simulations and measurements is obtained. Device design optimization is proposed, promising more than 700% efficiency.     

Ion-implanted GaAs for subpicosecond optoelectronic applications

Ion implantation is shown to be able to shorten the carrier lifetime in semi-insulating GaAs independent of the ion species. Although ion implantation alone may shorten the lifetime to the order of femtoseconds, to obtain good resistivity and mobility an annealing process is required. Furthermore, chemically active ions may complicate the recovery of resistivity, such as Si which may be activated as dopants during annealing or O which creates additional deep levels. Optimum annealing temperature was determined to be around 600°C with carrier lifetime still in the picosecond range but with mobility ~2000 cm²V.s. The shortening of the carrier lifetimes and electrical properties of these materials are correlated to the structural properties     

用于GaAs高速集成电路芯片的电光采样分析仪

本文介绍了一种实用的电光采集分析仪,其稳定的光学系统结构可保持精度几年不变,单位带宽电压灵敏度为２．５２ｍＶ根号Ｈｚ,空间分辨率３μｍ,测量带宽２０ＧＨｚ。用此分析仪对ＧａＡｓ高速动态二分频器芯片进行了在片测试,其测量波形与理论分析一致。     

Effect of quantum dots on InAs/GaAs p-i-p quantum dots infrared photodetectors

ABSTRACT

In this paper, the InAs/GaAs p-i-p quantum dots infrared photodetectors (QDIPs) were successfully demonstrated by Apsys software. It consists of Al_0.3Ga_0.7As/GaAs structure to reduce dark current and InAs quantum dots (QDs) embedded in In_0.15Ga_0.85As as an active layer. The effect of structure parameters of InAs QDs on the dark current, photocurrent of the device and SNR (signal to noise) is discussed respectively, including different QDs density, the number of QD layer, GaAs thickness between QDs layers and Al_0.3Ga_0.7As, and GaAs thickness between two the QD layers.     

Safe operating area of GaAs MESFET for nonlinear applications

This paper provides a new approach to evaluate the transistor safe operating area for a nonlinear operation in the overdrive operating conditions. This approach has been implemented for a MESFET technology. The methodology consists in performing ON-state and OFF-state accelerated DC step stresses for bias conditions, which can be reached by V/sub DS/ and V/sub GS/ sweeps in the overdrive operating conditions. Hence, the results of an RF ageing test performed in nonlinear conditions have confirmed the methodology used in this paper.     

20-nm T-gate composite channel enhancement-mode metamorphic HEMT on GaAs substrates for future THz applications

In this paper, the RF and DC behaviours of a SiN-passivated 20-nm gate length metamorphic high electron mobility transistor (MHEMT) on GaAs substrate with \({\updelta }\)-doped sheets on either side of the composite channel are studied using the Synopsys TCAD tool. The 20-nm enhancement-mode MHEMT with \({\updelta }\)-doped sheets on either side of the \(\hbox {In}_{0.75}\hbox {Ga}_{0.25}\hbox {As}\)/InAs/ \(\hbox {In}_{0.75}\hbox {Ga}_{0.25}\hbox {As}\) multilayer channel shows a transconductance of 3000 mS/mm, cut-off frequency (\({f}_{\mathrm{T}}\)) of 760 GHz and a maximum-oscillation frequency (\({f}_{\mathrm{max}}\)) of 1270 GHz. The threshold voltage of the device is found to be 0.07 V. The room-temperature Hall mobilities of the two-dimensional sheet charge density (2DEG) are measured to be over \(12800\,\hbox {cm}^{2}\)/Vs with a sheet charge density larger than 4 \(\times \) \(10^{12}\,\hbox {cm}^{-2}\). These high-performance enhancement-mode MHEMTs are attractive candidates for future terahertz applications such as high-resolution radars for space research and also for low-noise wide-bandwidth amplifier for future communication systems.     

Resonant cavity enhanced Ge photodetectors for 1550 nm operation on reflecting Si substrates

We have fabricated and characterized the first resonant cavity-enhanced germanium photodetectors on double silicon-on-insulator substrates (Ge-DSOI) for operation around the 1550-nm communication wavelength and have demonstrated over four-fold improvement in quantum efficiency compared to its single-pass counterpart. The DSOI substrate is fabricated using an ion-cut process and optimized for high reflectivity (>90%) in the 1300-1600-nm wavelength range, whereas the Ge layer is grown using a novel two-step ultra-high vacuum/chemical vapor deposition direct epitaxial growth technique. We have simulated a Ge-DSOI photodetector optimized for operation at 1550 nm, exhibiting a quantum efficiency of 76% at 1550 nm given a Ge layer thickness of only 860 nm as a result of both strain-induced and resonant cavity enhancement. For this Ge thickness, we estimate a transit time-limited 3-dB bandwidth of approximately 25 GHz.     

Study on Assembly Method for GaAs Nanowires Device

The assembly and fabrication method for Gallium arsenide (GaAs) nanowires nano devices was implemented. Assembly of GaAs nanowires field effect transistor (FET) was realized by dielectrophoresis approach. Before deposition of the contacts, GaAs nanowires were treated wet etching in an ammonium polysulfide ((NH₄)₂S) solution to remove a surface oxide layer. The assembled devices were characterized by atomic force microscopy. The experimental results showed that the efficient assembly of GaAs nanowires was obtained when the applied alternating current voltage has a frequency of 1.5MHz and an amplitude of 10 V, and the success rate of ideal assembly for GaAs nanowires FET had been assessed. Meanwhile, it also provided an effective assembly method for other one-dimensional nanomaterials assembly of nano devices.     

锑化铟霍尔器件在电子罗盘中的应用研究

本文研究了锑化铟(Insb)霍尔器件在电子罗盘系统中的应用前景。假设误差的形成为从圆到椭圆的变化过程,并利用该假设推导了椭圆误差补偿算法。证明了利用这种算法可以实现电子罗盘的自动校准,从而大量节约成本。这种算法应用于本实验获得了最大±3.0°的精度,从而表明用锑化铟霍尔器件应用应用于电子罗盘并配合椭圆补偿算法达到了实际需要,并且采用这种方法研制的电子罗盘具有成本低、体积小、重量轻、可靠性高、使用方便的特点。     

数字合成高速脉冲的一种非线性调理技术

结合数字合成脉冲的技术特点及信号特征,提出利用恒流源差分放大电路具有非线性工作区的特点实现高频脉冲信号调理的方法。调理电路通过精密控制恒流源调整脉冲信号的输出幅度,脉冲信号的电平控制则是通过恒压源控制实现的。文章给出了脉冲信号特征分析,差分放大电路的非线性工作原理,非线性调理电路的具体设计实现与测试结果。     

High-speed advanced sensors for bioterror weapons

"Biological weapons" include bacteria, viruses, and toxins that are spread deliberately in air, food, or water to cause disease or death to humans, animals, or plants. This discourse addresses specifically the applicability of integrated sensors and the use of technologies (both information technologies and biological/pharmaceutical technologies) in a concerted threat identification and avoidance paradigm designed to alert, to muster, and to deploy assets in counterterrorist efforts, specifically: Do we work to identify threats far enough in advance to allow proper response? What more needs to be done? What is the worth (value) of we can do now; what do we hope to do in the future?     

GaAs transit-time diodes for D-band frequencies

Contents Tunneling assisted GaAs avalanche transit-time diodes with oscillation frequencies between 140 and 170 GHz are presented. The device design results in a relatively low dc-voltage of 8 Volts. A non-alloyed Schottky contact instead of an ohmic contact on highly doped GaAs reduces losses at rf-frequencies. Cw-output power of 10 mW at 142 GHz and 1.3 mW at 170 GHz are attained in fundamental mode with devices on diamond heat-sinks. The diodes show an excellent noise behaviour resulting in a noise measure of only 26.5 dB at 170 GHz.

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GaAs Laufzeitdioden für D-Band Frequenzen

Übersicht In dieser Arbeit werden GaAs-Laufzeitbauelemente für den Frequenzbereich von 140 GHz bis 170 GHz beschrieben, bei denen die Ladungsträgergeneration durch tunnelstromunterstützte Lawinenmultiplikation erreich wird. Der Bauelemententwurf resultiert in einer relativ niedrigen Betriebsspannung von 8 Volt. Die Verluste im Bauelement konnten durch die Verwendung eines nicht legierten Schottky-Kontakts auf hochdotiertem GaAs-Material anstelle eines ohmschen Kontakts merklich reduziert werden. Für Bauelemente auf Diamantwärmesenken konnten Hochfrequenzausgangsleistungen von 10 mW bei 142 GHz und 1,3 mW bei 170 GHz im Grundwellenmodus erzielt werden. Die Dioden zeigen ein sehr gutes Rauschverhalten mit einem Rauschmaß von nur 26,5 dB bei 170 GHz.

     

一种反向多结GaAs太阳电池背反射器的研究

介绍了一种具有全方位反射器的GaAs太阳电池的制作方法;分析了GaAs太阳电池全方位反射器制备工艺,在GaAs外延上生长全方位反射器ODR,即生长一层介质层,再在介质层上用黄光工艺进行开孔;并在介质层上使用蒸镀工艺蒸镀金属层。通过蒸镀、键合、衬底腐蚀、栅线、背电极制作等工艺完成电池制作。介绍了ODR结构的设计及工艺,并对比了实验结果。     

A Deterministic Solver for the 1D Non-Stationary Boltzmann-Poisson System for GaAs Devices: Bulk GaAs and GaAs n +-n i -n + Diode

We present a deterministic method for describing the electron transport in spatially one-dimensional gallium arsenide devices. This numerical procedure is based on the combination of kinetic Boltzmann-type equations for a two-valley model of the GaAs conduction band and the Poisson equation in order to consider the electrostatic potential self-consistently. All of the important intra- and intervalley scattering mechanisms for GaAs are taken into account. The dependence of the electron distribution functions on the electron wave vector is treated by means of the multigroup approach, whereas their spatial dependences are handled by a weighted essentially non-oscillatory (WENO) scheme. Numerical results are given for the main transport quantities as functions of time, position and electric field in bulk material and in a n⁺-n_i-n⁺ diode. In addition, the proposed numerical method is validated by comparing the results with those of Monte Carlo calculations and the influence of the discretization used in the numerical procedure is discussed.     

基于SoPC的高速通信接口设计

基于FPGA的可编程片上系统（SoPC）以其设计灵活、可裁剪、软硬件可在线编程等特点和优势,成为嵌入式系统设计,乃至电子领域发展的一个重要方向。用户IP核的设计是SoPC设计的重要组成部分,介绍了通信系统的SoPC系统架构,提出利用IPIF将用户IP核挂载到PLB总线上的方法,给出了RLC和物理层接口的IP核的设计与实现。设计中首先把IPIF信号转换成用户逻辑的内部信号,同时对不同速率的接口进行数据缓存,实现流水线传输,从而提高传输速率。