Fabrication of low cost Si-based tunable high performance resonant cavity enhanced photodetectors

Low cost Si-based tunable InGaAs RCE photodetectors operating at 1.3similar to1.6 mum were fabricated using sol-gel bonding. A tuning range of 14.5 nm, a quantum efficiency of 44% at 1476 nm and a 3-dB bandwidth of 1.8 GHz were obtained.

Recent progresses of silicon-based optoelectronic devices for application in fiber communication

Si-based optoelectronic devices, including stimulated emission from Si diode, 1.3 and 1.5mum SiGe photodetector with quantum structures, 1GHz MOS optical modulator, SOI optical switch matrix and wavelength tunable filter are reviewed in the paper.

Kinetics of picosecond laser pulse induced charge separation and proton transfer in bacteriorhodopsin

Bacteriorhodopsin (BR) films oriented by an electrophoretic method are deposited on a transparent conductive ITO glass. A counterelectrode of copper and gelose gel is used to compose a sandwich-type photodetector with the structure of ITO/BR film/gelose gel/Cu. A single 30-ps laser pulse and a mode-locked pulse train are respectively used to excite the BR photodetector. The ultrafast failing edge and the bipolar response signal are measured by the digital oscilloscope under seven different time ranges. Marquardt nonlinear least squares fitting is used to fit all the experimental data and a good fitting equation is found to describe the kinetic process of the photoelectric signal. Data fitting resolves six exponential components that can be assigned to a seven-step BR photocycle model: BR-->K-->KL-->L-->M-->N-->O-->BR. Comparing tests of the BR photodetector with a 100-ps Si PIN photodiode demonstrates that this type of BIR photocletector has at least 100-ps response time and can also serve as a fast photoelectric switch. (C) 2003 Society of Photo-Optical Instrumentation Engineers.

Abnormal photoabsorption in high resistance GaN epilayer

Unintentionally doped GaN epilayers are grown by the metalorganic chemical vapor deposition (MOCVD). Photovoltaic (PV) spectroscopy shows that there appears an abnormal photoabsorption in some undoped GaN films with high resistance. The peak energy of the absorption spectrum is smaller than the intrinsic energy band gap of GaN. This phenomenon may be related to exciton absorption. Then metal-semiconductor-metal (MSM) Schottky photodetectors are fabricated on these high resistance epilayers. The photo spectrum responses are different when the light individually irradiates each of the two electrodes with the photodetector which are differently biased. When the excitation light irradiates around the reverse biased Schottky junction, the responsivity is almost one order of magnitude larger than that around the forward biased junction. Furthermore, when the excitation light irradiates the reverse biased Schottky junction, the peak energy of the spectrum has a prominent red-shift compared with the peak energy of the spectrum measured with the excitation light irradiating the forward biased Schottky junction. The shift value is about 28 meV, and it is found to be insensitive to temperature. According to the analyses of the distribution of the electric field within the MSM device and the different dependences of the response on the electric field intensity between the free carriers and excitons, a reliable explanation for the different response among various areas is proposed.

Intersubband absorption from In0.26Ga0.74As/GaAs quantum dot superlattice

We have grown a high-quality 20 period InGaAs/GaAs quantum dot superlattice with a standard structure typically used for quantum well infrared photodetector. Normal incident absorption was observed around 13-15 mu m. Potential applications for this work include high-performance quantum dot infrared detectors.

A High Speed, 12-Channel Parallel, Monolithic Integrated CMOS OEIC Receiver

The design and fabrication of a high speed, 12-channel monolithic integrated CMOS optoelectronic integrated circuit(OEIC) receiver are reported.Each channel of the receiver consists of a photodetector,a transimpedance amplifier,and a post-amplifier.The double photodiode structure speeds up the receiver but hinders responsivity.The adoption of active inductors in the TIA circuit extends the-3dB bandwidth to a higher level.The receiver has been realized in a CSMC 0.6μm standard CMOS process.The measured results show that a single channel of the receiver is able to work at bit rates of 0.8～1.4Gb/s. Altogether, the 12-channel OEIC receiver chip can be operated at 15Gb/s.

高功率共振腔增强型光电探测器研究进展

共振腔增强型光电探测器(RCE-PD)作为一种新型光电探测器,具有高量子效率、高响应度和波长选择性等优点,成为目前光纤通信领域中最为重要的探测器之一.在数字和模拟光传输系统中,高功率探测器由于具有高信噪比、低插入损耗等优点,在国际上越来越受到重视.综述了这两种探测器的基本结构、发展状况,展望了其发展前景等.指出高功率共振腔增强型光电探测器将是今后最有发展前途的探测器.

1．55μm低温生长GaAs谐振腔增强型探测器

利用低温（200℃）生长的GaAs材料作为吸收层制备了GaAs基1．55μm谐振腔增强型（RCE）光电探测器，对其光电特性进行了分析、研究．无光照0偏压下探测器暗电流为8．0×10^12A；光电流谱峰值波长1563nm；响应谱线半宽4nm，具有良好的波长选择性．

带有Bragg反射镜的谐振腔增强型Si光电探测器

采用电子束蒸发和键合技术，制作了具有高反射率的、表面为薄层单晶Si的分布Bragg反射器。用标准光刻工艺在单晶Si薄层上制作出窄带谐振腔增强型（RCE）金属一半导体一金属（MSM）光电探测器，响应峰值波长分别在836、900、965和1030nm处，其中在900nm处峰值半高宽为18nm。该器件具有波长选择特性，可有效抑制相邻频道间的串扰，而且容易制成集成面阵。

用于光网络通信的Si基光子集成器件的研究

报导了可用于光网络系统终端OADM和OXC的Si基长波长量子阱窄带响应光电接收器，MOEMS和F-P TO宽频域光学滤波器，M—Z型TO光开关和MMI多路分束器以及可变光强衰减器．用应变层SiGe/Si MQW研制的RCE光电接收器响应谱半宽FWHM<6mm，外量子效率η>4．2％；采用表面微机械加工的桥式光学滤波器，当外加电压0→50V，连续可调谐范围达90nm；采用全平面工艺研制的F-P腔TO滤波器，当外加电流0→57mA时，连续可调谐范围达23nm，FWHM<0．5nm．在SOI Si基片上研制的M—ZTO波导光开关，开关时间<30μs，功耗～100mW．开关消光比-13dB和-10dB，1×4MMI多路分束器输出光场的不均衡性<0．36dB，总插入损耗6．9dB．用背向对接的MMI构成的M-Z干涉仪实现了光强的可变调最大衰减量26dB，响应时间100μs，插入损耗4．8～7dB．

Fabrication of 1.55μm Si-Based Resonant Cavity Enhanced Photodetectors

A novel bonding method using silicate gel as bonding medium is developed.High reflective SiO2/Si mirrors deposited on silicon substrates by e-beam deposition are bonded to the active layers at a low temperature of 350℃ without any special treatment on bonding surfaces.The reflectivities of the mirrors can be as high as 99.9%.A Si-based narrow band response InGaAs photodetector is successfully fabricated,with a quantum efficiency of 22.6% at the peak wavelength of 1.54μm,and a full width at half maximum of about 27nm.This method has a great potential for industry processes.

GaAs/GaInNAs多量子阱谐振腔增强型长波长光探测器

报道了一种具有高速响应特性的GaAs基长波长谐振强增强型(RCE)光探测器,它采用分子束外延技术(MBE)在GaAs衬底上直接生长GaAs/AlAs布拉格反射镜(DBR)和GaInNAs/GaAs多量子阱吸收层而形成,解决了GaAs系材料只能对短波长光响应的问题,实现了GaAs基探测器对长波长光的响应.该器件在峰值响应波长1 296.5 nm处获得了17.4%的量子效率,响应谱线半宽为11 nm,零偏置时的暗电流密度8.74×10-15 A/μm~2,具有良好的暗电流特性.通过RC常数测量计算得到器件的3 dB带宽为4.82 GHz.

超薄有源层谐振腔增强型调制器

提出利用超薄有源层制备高性能谐振腔增强型(RCE)半导体电吸收调制器件的可能性,并与波导型器件进行性能对比;对透射和反射两种类型器件优化分析了器件结构,进行了性能比较,结果表明:在插入损耗相当的情况下,反射式器件具有更高的调制对比度.

1.55-μm Si-based MOEMS optical tunable filter

A prototype 1.55-μm Si-based micro-opto-electro-mechanical-systems (MOEMS) tunable filter is fabricated, employing surface micromachining technology. Full-width-at-half-maximum (FWHM) of the transmission spectrum is 23 nm. The tuning range is 30 nm under 50-V applied voltage. The device can be readily integrated with resonant cavity enhanced (RCE) detector and vertical cavity surface emitting laser (VCSEL) to fabricate tunable active devices.

基于InP／空气隙布拉格反射镜的长波长谐振腔光电探测器

报道了一种长波长的InP基谐振腔(RCE)光电探测器．采用选择性湿法刻蚀，制备出基于InP／空气隙的分布布拉格反射镜，并将该结构的反射镜引人RCE光电探测器．制备的器件在波长1.510μm处获得了约59％的峰值量子效率，以及8GHz的3dB响应带宽，其中器件的台面面积为50μm * 50μm．