电力系统暂态大电流测量用电子互感器研究

本文研究了电力系统中用于暂态大电流测量的Rogowski线圈电流传感器传感头的频率特性,分析了不同终端电阻值的选取对线圈测量带宽的影响,在此基础上设计一种将无源外积分、有源外积分相结合的复合式积分信号处理电路,论述了复合式外积分器能够在保证传感器具有合适灵敏度的前提下,将传感器的工作频带由低频提高到线圈的谐振频率附近;最后,文中以自制的灵敏度为2mV／A的复合式外积分罗氏线圈为例,给出参数设计过程和实验波形,对50Hz电网电流与250A/μs上升沿的脉冲电流的准确检测验证了该信号处理电路较其他外积分电路可工作在更宽的测量范围。     

Fabrication of infrared photodetectors

Abstract

This paper presents the fabrication of an integrated optoelectronic circuit consisting of a waveguide and photodetector. Fabrication of the waveguides took place in a RIBE system with 1·5 sccm CH₄/H₂ (60:40) and 0·5 sccm Ar. Wet etching defines the photodetector regions. The detection of surface damage is minimal, using a novel differential optical reflectance technique.     

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.     

Polarization sensing with resonant cavity enhanced photodetectors

We describe a new method of sensing the linear polarization of light using resonant cavity enhanced (RCE) photodetectors. The RCE detectors are constructed by integrating a thin absorption region into an asymmetric Fabry-Perot cavity. The top reflector is formed by the semiconductor air interface while the bottom mirror is a distributed Bragg reflector (DBR). Quantum efficiency of these RCE devices can be controlled by tuning the cavity length by recessing the top surface of the detector for off-normal incidence of light the reflectivity of the semiconductor-air interface can be significantly different for TE(s) and TM(p) polarizations. A pair of monolithically integrated RCE photodetectors with cavity lengths tuned for resonance and antiresonance provide a large contrast in response to TE and TM polarizations. An alternative polarization sensor can be formed by vertically integrating a conventional and a RCE photodetector. We show that a large contrast in the TE/TM responsivities of the vertical cavity polarization detectors (VCPD) can be achieved, thus combining detection and polarization sensing in a single mesa semiconductor device. These devices alleviate the problems associated with the bulkiness and critical alignment constraints of the conventional sensors based on polarizing filters or splitters and have potential for fabrication of monolithic smart pixels and imaging arrays     

High-speed InSb photodetectors on GaAs for mid-IR applications

We report p-i-n type InSb-based high-speed photodetectors grown on GaAs substrate. Electrical and optical properties of photodetectors with active areas ranging from 7.06/spl times/10/sup -6/ cm/sup 2/ to 2.25/spl times/10/sup -4/ cm/sup 2/ measured at 77 K and room temperature. Detectors had high zero-bias differential resistances, and the differential resistance area product was 4.5 /spl Omega/ cm/sup 2/. At 77 K, spectral measurements yielded high responsivity between 3 and 5 /spl mu/m with the cutoff wavelength of 5.33 /spl mu/m. The maximum responsivity for 80-/spl mu/m diameter detectors was 1.00/spl times/10/sup 5/ V/W at 4.35 /spl mu/m while the detectivity was 3.41/spl times/10/sup 9/ cm Hz/sup 1/2//W. High-speed measurements were done at room temperature. An optical parametric oscillator was used to generate picosecond full-width at half-maximum pulses at 2.5 /spl mu/m with the pump at 780 nm. 30-/spl mu/m diameter photodetectors yielded 3-dB bandwidth of 8.5 GHz at 2.5 V bias.     

Modeling the performance characteristics of ZnO-based heterojunction photodetectors

We propose and experimentally validate a theoretical closed-form modeling procedure for ZnO-based heterojunction ultraviolet (UV) photodetectors. To do so, we first employ a deposition and growth method based on chemical bath deposition for a typical ZnO/CuO n–p heterojunction structure. The UV detection performance of this type of detector has been examined and confirmed previously. The fabricated device was then tested, and its performance analyzed. We model the performance of the detector by extension of previously proposed analytical models and study the performance of the device. The results show good agreement between the measurements and theoretical modeling.     

Traveling-wave photodetectors with high power-bandwidth and gain-bandwidth product performance

Traveling-wave photodetectors (TWPDs) are an attractive way to simultaneously maximize external quantum efficiency, electrical bandwidth, and maximum unsaturated output power. We review recent advances in TWPDs. Record high-peak output voltage together with ultrahigh-speed performance has been observed in low-temperature-grown GaAs (LTG-GaAs)-based metal-semiconductor-metal TWPDs at the wavelengths of 800 and 1300 nm. An approach to simultaneously obtain high bandwidth and high external efficiency is a traveling-wave amplifier-photodetector (TAP detector) that combines gain and absorption in either a sequential or simultaneous traveling-wave structure.     

Silicon/2D-material photodetectors: from nearinfrared to mid-infrared

Two-dimensional materials (2DMs) have been used widely in constructing photodetectors (PDs) because of their advantages in flexible integration and ultrabroad o...     

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.     

Semiconductor quantum-dot nanostructures: Their application in anew class of infrared photodetectors

Semiconductor quantum-dot nanostructures are interesting objects for fundamental as well as practical reasons. Fundamentally, they can form the basis of systems in which to study the quantum mechanics of electrons confined in zero-dimensional (0-D) space. In practice, the dots can be embedded in the active regions of a new class of electronic and optoelectronic devices with novel functionalities. This paper reviews the state-of-the-art in the use of these objects in infrared detectors. It describes the progress, challenges, and projections for continued development of normal-incidence intersublevel detectors operating in the spectral region between 6 and 20 μm     

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.     

Linear array of Si-Ge heterojunction photodetectors monolithically integrated with silicon CMOS readout electronics

We describe a linear array of Ge-Si heterojunction photodiodes monolithically integrated on a complementary metal-oxide-semiconductor (CMOS) integrated circuit for detection and imaging in the near infrared. Detectors are realized by thermal evaporation of Ge films at the end of the standard CMOS process on substrates held at low temperature (300/spl deg/C). Each of the 64 detectors is connected to a front-end stage for photocurrent integration and analog-to-digital conversion.     

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.     

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.     

Modulation and free-space link characteristics of monolithicallyintegrated vertical-cavity lasers and photodetectors with microlenses

We present temperature, modulation, and free-space link characteristics of monolithically integrated vertical-cavity lasers (VCLs) and resonant photodetectors. The devices have been integrated using a novel structure that makes it possible to fabricate devices with through-the-substrate emission and detection. Taking advantage of the substrate emitting/detecting architecture, we monolithically integrate microlenses on the substrate side of the devices and flip-chip bond arrays without via processes or substrate removal. Low-threshold high-efficiency VCLs exhibit maximum small-signal modulation bandwidths, which are limited by parasitics, of ~9.5 GHz at 20°C and ~8.4 GHz at 70°C. The VCLs have the lowest reported bias currents required to reach bandwidths of up to ~8 GHz. A free-space optical link is demonstrated with flip-chip-bonded arrays of microlensed, monolithically integrated VCLs and detectors. The link is found to be tolerant to temperature differences of ±75°C between the VCL and detector, with error free (BER<10^-12) data transmission demonstrated in each case     

MXene-GaN van der Waals metal-semiconductor junctions for high performance multiple quantum well photodetectors

A MXene-GaN-MXene based multiple quantum well photodetector was prepared on patterned sapphire substrate by facile drop casting. The use of MXene electrodes imp...     

Engineered tunneling layer with enhanced impact ionization for detection improvement in graphene/silicon heterojunction photodetectors

Here, an engineered tunneling layer enhanced photocurrent multiplication through the impact ionization effect was proposed and experimentally demonstrated on th...     

Fabrication and performance of two-dimensional matrix addressable arrays of integrated vertical-cavity lasers and resonant cavity photodetectors

Massively parallel interconnects and scannerless imaging are applications that would benefit from high-density two-dimensional arrays of lasers. Vertical-cavity surface-emitting lasers (VCSELs) are uniquely suited for these applications due to their small size and high efficiency. We have successfully fabricated 64 /spl times/ 64 element arrays containing alternating rows of selectively-oxidized 850 nm VCSELs and resonant-cavity photodetectors (RCPDs) monolithically integrated on semi-insulating GaAs substrates. In order to reduce the input and output connections to the array, we employ a matrix addressable architecture, where all the VCSELs (or RCPDs) in each row are connected by a common metal trace at the base of their mesas. The columns are connected by metal traces that bridge from mesa top to mesa top, connecting every other row (i.e., only VCSELs or only RCPDs). The pitch of devices in the array is 55 /spl mu/m, and the total resistance contributed by the long (up to 3.5 mm) row and column traces is below 50 /spl Omega/. The design, fabrication, and performance of these arrays are discussed.