具有优化倍增层InAlAs/InGaAs雪崩光电二极管

通过优化倍增层的厚度,研究了InAlAs/InGaAs雪崩光电二极管增益带宽积和暗电流之间的关系。利用仿真计算得出200 nm厚的倍增层能够改善增益带宽积并降低暗电流。制成的InAlAs/InGaAs 雪崩光电二极管性能优异,与计算趋势一致。在获得0.85 A/W的高响应和155 GHz的增益带宽积的同时,器件暗电流低于19 nA。这项研究对雪崩光电二极管在未来高速传输的应用具有重要意义。     

大面积1.54μm波长测距用InGaAs雪崩光电二极管

设计并研制成功适合人的眼睛安全测距应用的ＩｎＧａＡｓ雪崩光电二极管（ＡＰＤ）。器件直径为２００μｍ，工作在２１℃，１５４０ｎｍ波长时响应为０．６４Ａ／Ｗ，典型暗电流和噪声因子分别为３０ｎＡ和６．５。介绍了该器件的工作原理，设计和制作工艺。     

氮化镓基雪崩光电二极管的研制

文章简单回顾了氮化镓基雪崩光电二极管的发展现状，从制作高响应率、低漏电流的雪崩器件出发，详细阐明了制作氮化镓基雪崩光电二极管的工艺过程，特别考虑了干法刻蚀带来的物理损伤以及后续的消除损伤处理。由于雪崩器件对于材料的质量具有较苛刻的要求，因此特别对材料进行了必要的筛选。通过一系列工艺上的改进，成功地制作出国内第一只氮化镓基雪崩光电二极管，器件的光敏面直径是40μm；并对其进行了光电性能测试。测试结果表明，当反向偏压是58V时，漏电流大约是1．18×10^-7A，雪崩增益是3。     

基于盖革模式雪崩光电二极管紫外计数系统

针对工作在盖革模式下的硅基雪崩光电二极管(APD)进行了接收电路的设计,通过主动淬灭加快恢复的方式,对APD偏压进行调控,利用单稳态触发器使淬灭信号和恢复信号独立控制APD阳极的电压,从而同时控制淬灭时间和恢复时间,将死时间缩短至100.5ns,计数频率提升到10MHz,有效减少了后脉冲效应。采用脉冲甄别技术和单片机,对脉冲信号进行计数,通过对可见盲光子计数和暗计数的甄别,实现对微弱紫外信号的检测,为盖革模式下APD紫外通信奠定了基础。     

氮化镓基雪崩光电二极管的研制

文章简单回顾了氮化镓基雪崩光电二极管的发展现状，从制作高响应率、低漏电流的雪崩器件出发，详细阐明了制作氮化镓基雪崩光电二极管的工艺过程，特别考虑了干法刻蚀带来的物理损伤以及后续的消除损伤处理。由于雪崩器件对于材料的质量具有较苛刻的要求，因此特别对材料进行了必要的筛选。通过一系列工艺上的改进，成功地制作出国内第一只氮化镓基雪崩光电二极管，器件的光敏面直径是40μm；并对其进行了光电性能测试。测试结果表明，当反向偏压是58V时，漏电流大约是1．18×10-7A，雪崩增益是3。     

雪崩光电二极管对空激光测距接收机

根据雪崩光电二极管最佳应用理论设计出一种新的激光测距接收机,其特有的雪崩管工作电压建立方式,使它能在很宽的温度范围内工作,具有极强的背景辐射环境适应性,已成功地用于对空激光测距。     

长波长高速雪崩光电二极管的理论研究

本文以现有的理论研究和实验研究的结果为依据,提出了长波长高速及超高速雪崩光电二极管(APD)的两设计原则:一是在雪崩管内建立合理的电场强度分布;二是尽可能减少电寄生。这是得到高速或超高速响应、高量子效率以及低噪声性能的根本途径。     

可作光子计数的雪崩光电二极管

对于光电倍增管不适用的高灵敏度弱光探测应用，存在一种固体替代器件，即雪崩光电二极管。这种器件在半导体内产生光电倍增，而光电倍增管在真空中产生电子倍增。雪崩光电二极管具有与半导体技术有关的微型化优点。由于这种器件能对单光子计数和探测很短时间间隔，它们已在光雷达、测距仪探测器和超灵敏光谱学方面找到日益增长的应用。另外，雪崩光电二极管在光纤通讯方面正与PIN光电二极管相竞争。雪崩光电二极管如何工作与任何光电二极管，样，雪崩光电二极管中由两类半导体组成的p-n结只允许电流在一个方向流动。光电二极管由一个掺有…     

超晶格雪崩光电二极管

已经提出了几种可以提高载流子离化率比的超晶格雪崩光电管:量子阱雪崩光电管、台阶型雪崩光电管和掺杂量子阱雪崩光电管。这几种器件都主要是利用异质界面带隙突变导致的电子离化几率相对于空穴离化几率的显著增大,从而可以获得低的雪崩噪声和高的增益—带宽乘积。本文概述了这几种器件的结构、工作原理以及结构参量对器件性能的影响。     

雪崩光电二极管芯片自动测试系统

利用Keithley 2400源表、AV6381可编程光衰减器、AV 38124 1 550 nm单模半导体激光器和TZ-608B型光电屏蔽探针台搭建雪崩光电二极管芯片自动测试系统.在Labview环境下开发了自动测试软件,通过软件控制测量仪表,实现了雪崩光电二极管芯片的击穿电压、暗电流、穿通电压及10倍增益工作点电压的自动测试及合格判定.探针台可以根据测量系统反馈的判定结果对不合格芯片进行NG标记,方便划片后对不合格芯片进行筛选和剔除.建立的自动测试系统准确性高,测试速度快,软件操作方便,显示结果直观.同时可以实现测试参数的自动存储,方便进行统计过程控制(SPC)分析.     

Buried-mesa avalanche photodiodes

We have developed a low-cost buried-mesa avalanche photodiode (APD) primarily targeted for 2.5-Gb/s lightwave applications. These APDs are made by a simple batch process that produces a robust and reliable device with potentially high yield and thus low cost. The entire base structure of our InGaAs-InP APD is grown in one epitaxial step and the remaining process consists of four simple steps including a mesa etch, one epitaxial overgrowth, isolation, and metallization. Buried-mesa APDs fabricated in this way show high uniform gain that rises smoothly to breakdown with increasing reverse bias. When biased to operate at a gain of 10, these unoptimized devices show dark current less than 20 nA, excess noise factor less than 5, and a 3-dB bandwidth of about 4 GHz. With a 1550-nm laser modulated at 2488 Mb/s, a maximum sensitivity of -327 dBm was obtained with an optical receiver using one such APD, without antireflection coatings. These APD's not only demonstrate excellent device characteristics but also high reliability under rigorous stress testing. No degradation was observed even after being biased near breakdown for over 2000 h at 200°C     

HgCdTe electron avalanche photodiodes

Exponential-gain values well in excess of 1,000 have been obtained in HgCdTe high-density, vertically integrated photodiode (HDVIP) avalanche photodiodes (APDs) with essentially zero excess noise. This phenomenon has been observed at temperatures in the range of 77–260 K for a variety of cutoff wavelengths in the mid-wavelength infrared (MWIR) band, with evidence of similar behavior in other IR bands. A theory for electron avalanche multiplication has been developed using density of states and electron-interaction matrix elements associated with the unique band structure of HgCdTe, with allowances being made for the relevant scattering mechanisms of both electrons and holes at these temperatures. This theory is used to develop an empirical model to fit the experimental data obtained at DRS Infrared Technologies. The functional dependence of gain on applied bias voltage is obtained by the use of one adjustable parameter relating electron energy to applied voltage. A more quantitative physical theory requires the use of Monte Carlo techniques incorporating the preceding scattering rates and ionization probabilities. This has been performed at the University of Texas at Austin, and preliminary data indicate good agreement with DRS models for both avalanche gain and excess noise as a function of applied bias. These data are discussed with a view to applications at a variety of wavelengths.     

Improved germanium avalanche photodiodes

New kinds of germanium avalanche photodiodes with n+-n-p and p+-n structures were devised for improved excess noise and high quantum efficiency performance. Multiplication noise, quantum efficiency, and pulse response were studied and compared with those of the conventional n+-p structure diode. Multiplication noise of the new type of diodes were measured in the wavelength range between 0.63 and 1.52 μm. The effective ionization coefficient ratio of the p+-n diode was lower than unity at a wavelength longer than 1.1 μm and 0.6-0.7 at 1.52 μm, and that of the n+-n-p diode was 0.6-0.7 in the whole sensitive wavelength region. Response times were evaluated by using a mode-locked Nd:YAG laser beam and a frequency bandwidth wider than 1 GHz was estimated. Receiving optical power levels were compared with each other using parameters measured in this study.     

Multi-element reachthrough avalanche photodiodes

Two approaches to making multi-element arrays of p⁺-π-p-n⁺reachthrough avalanche photodiodes are reported. In the first approach a single common avalanche region (p-layer) for all elements is used, with the segmentation between elements being on the p⁺layer. This approach has the advantage of having zero dead space between adjacent elements, but is difficult to fabricate, and has a very narrow range of operation in which it is neither noisy due to injection nor suffers from poor element-to-element isolation. In a second approach, the p⁺contact is common and separate avalanche regions are used. The problem for this case is the width of the dead space between adjacent elements which, because of field-fringing effects, is considerably wider than the actual physical distance between elements. A self-aligning technique is described for fabricating arrays by the second approach and the technique demonstrated with a 25-element linear array on 300-µm centers. The measured dead space is in the 60-80 µm range, depending on the gain. The array can be used at an average gain of 100 or more, has excellent element-to-element isolation, and NEP's below 2 × 10¹⁵W/Hz^1/2at 800-900 nm and below 10^-14W/ Hz^1/2over the whole spectral range from 400 to 1060 nm.     

Pulse response of avalanche photodiodes

A study has been made of the time response of heterostructure avalanche photodiodes for InGaAs and InP/InGaAs material systems. A transfer/scattering matrix method, where the matrix parameters are related to the ionization coefficients, has been used. A time domain study has been carried out to find the time variation of electron and hole number densities and currents     

Silicon Geiger mode avalanche photodiodes

In this letter we present the results regarding the electrical and optical characterization of Geiger mode silicon avalanche photodiodes(GMAP) fabricated by silicon standard planar technology. Low dark count rates,negligible afterpulsing effects,good timing resolution and high quantum detection efficiency in all the visible range have been measured. The very good electro-optical performances of our photodiodes make them attractive for the fabrication of arrays with a large number of GMAP to be used both in the commercial and the scientific fields,as telecommunications and nuclear medical imaging.     

Arrays of Geiger mode avalanche photodiodes

Following our previous work which has led us to fabricate single pixels of geiger mode avalanche photodiodes (GMAPs), we present in this letter the results regarding the fabrication and characterization of a bidimensional array of GMAPs. Low dark count rates and very good uniformity over the sensor are reported. High quantum efficiency in the visible range has been measured. Measurements indicate that not all the nominal active area is effectively sensitive. We have some preliminary evidence that no crosstalk effects are present in our device. Notwithstanding this, in view of a near future shrinking of all dead regions, an optical trench process has been developed and is illustrated here. Possible future trends are highlighted.     

Low dark current GaN avalanche photodiodes

We report the fabrication and characterization of GaN avalanche photodiodes grown on sapphire by metalorganic chemical vapor deposition. Current-voltage characteristics indicate a gain higher than 23. The photoresponse is independent of the bias voltage prior to the onset of avalanche gain which occurs at an electric field of ~4 MV/cm. Near avalanche breakdown, the dark current of a 30-μm diameter device is less than 100 pA. The breakdown shows a positive temperature coefficient of 0.03 V/K that is characteristic of avalanche breakdown     

InP/InGaAs buried-structure avalanche photodiodes

Planar InP/InGaAs avalanche photodiodes with a new guardring structure have been designed and fabricated. The diodes had a buried n-InP layer and an n?-InP multiplication region under p-n junctions. A successful guardring effect was obtained. The diode exhibited a uniform multiplication over the active region, a maximum multiplication factor of 30, low dark currents of around 20 nA at 90% of breakdown voltage and a flat frequency response up to 1 GHz. Multiplication noise was measured up to a multiplication factor of 17.     

Multiplication noise in multi-heterostructure avalanche photodiodes

Using a multi-feedback network representation, multiplication noise in two-stage and three-stage heterostructure avalanche photodiodes has been calculated for different degrees of carrier feedback over heterobarriers. Results show appreciable dependence of noise on carrier feedback in III–V compound APD's, the effect being less with larger number of stages.