AlGaAs-GaAs DH激光器退化特性及P-I特性

研究了质子轰击条形双异质结构(DH)激光器的退化特性及P-I 特性,发现一般快退化器件 CW工作寿命小于 200小时.损坏后用 EBIC方法观察到有源区中增殖着暗线缺陷. DH激光器CW工作寿命超过200小时,而且每千小时的退化率小于4％的器件,一般cw工作寿命都能超过5000小时,有的器件已超过8000小时***仍在继续工作. 大部分器件具有良好的线性P-I特性,也有的观察到出现扭折“Kink”,结合近场观测和发射光谱的研究,判定这是由于激光器有源区中Al含量(即x值)的不均匀分布所致.     

(GaAl)As/GaAs质子轰击隔离条形DH激光器退化原因

(GaAl)As/GaAs质子轰击隔离条形双异质结构(DH)激光器是在(100)GaAs衬底上连续生长五层结构:n-GaAs;N-Al_(0.35)Ga_(0.65)As;p-GaAs(有源层);P-Al_(0.35)Ga_(0.65)AS和p-GaAs。p面浅扩Zn后利用质子浅轰击造成高阻隔离区,制成12微米宽的条形DH激光器。激光器管芯端面没有镀膜保护,但安装在充氮密封的可卸管壳内。 老化考验采用恒定功率(1毫瓦、2毫瓦和5毫瓦),考验环境温度分别为室温、50℃、70℃及80℃。考验结果表明,退化行为可分为快、慢两类。快退化激光器在工作期间阈电流不断显著上升,外微分量子效率迅速下降,激射时间都小于200小时。由电子束感生电流象可知,这是由于有源区内存在暗点、暗线或暗区之类的缺陷,在器件工作过程中这类缺陷不断扩大、增殖,器件很快就无法维持激射。暗点、暗线等是外延层内的位错网络缺陷。它来源于衬底原     

MOCVD工艺生长的可见光窄条激光器的可靠性和均匀性

我们首次报导了MOCVD生长的质子轰击隔离窄条结构可见光激光器系统的寿命试验结果。在大面积衬底(直径50mm)上生长了(Al_xGa_(1-x))As有源层(x=0.13)和限制层(x=0.43)常规DH站构。该激光器具有“自校准质子隔离窄条”结构。在条宽和质子注入深度上,该结构是最佳化,即掩膜宽5μm,在有源层上方0.5μm。对于一个由31块芯片组成的、腔长220μm的条形试验样品(样品长13mm)来说,其CW阈值电流约53mA,其标准偏差低达1.4%(图1)。其均匀性堪与在这类激光器中已获得的最佳结果相比。激射波长为     

半导体GaAlAs激光器工作寿命的研究

本文论述了半导体激光器工作寿命的计算原理,给出我们的质子轰击条型GaAlAs DH激光器室温连续工作104～105小时的实验结果,并分析了这种激光器的失效机理。     

室温连续工作寿命大于3000小时的质子轰击条型GaAs—AlGaAs DH激光器的研究

本文报导了在研制室温连续工作寿命大于3000小时的质子轰击条型GaAs—AlGaAs DH激光器中影响寿命的几个因素,这主要是(ⅰ) 为生长大面积光亮的、层次连续重复、Al分布均匀及异质结低失配的LPE生长技术,(ⅱ) 镜面保护技术;(ⅲ) 采用抗氧化力强的焊料键合。此外还报导了所研制激光器的主要电光参数及其寿命大于3000小时的实验结果。     

GaAs-GaAlAs DH激光器暗线(DLD)的观察

<正> 一、引 言 GaAs-GaAlAs双异质结激光器(以下简称 GaAlAs DH激光器)的退化是人们很关心的问题.现在看来,器件退化主要有二种形式:快退化和慢退化.GaAlAs DH激光器有源区暗线的增长是器件快退化的主要原因之一.暗线的形成一般在几分钟到几十小时,因此在器件短期老化后如能方便地对器件内部发光情况进行观察并结合进行如阈值、微分量子效率、热阻、伏安特性等测试,将有助于器件退化原因的分析,有利于改进外延与制     

大功率半导体激光器的可靠性研究

文中介绍了半导体激光器寿命测试的理论依据,给出寿命测试的数学模型,据此对InGaAsP/GaAs有源区无铝的808nm大功率半导体激光器进行高温恒流加速老化实验,得到器件在高温下的寿命,利用外推公式推算出激光器在室温条件下工作的寿命可超过30000小时。讨论了实验中出现的灾变退化,提出了防止灾变退化的几种方法。     

质子辐射导致CCD热像素产生的机制研究

空间高能质子作用于电荷耦合器件(CCD)产生的热像素是空间成像系统性能退化的主要原因之一。为深入认识质子辐射导致CCD产生热像素的规律和机制,对行间转移CCD进行了不同能量(3,10,23 MeV)的质子辐射试验,研究了辐射导致CCD暗信号的退化和热像素产生的规律。试验结果表明,在较低辐射注量1E9 p/cm²下,CCD的暗信号退化很小,但热像素急剧增加。质子辐射能量越大,产生的热像素数量越多。结合粒子输运计算与理论分析表明,热像素产生原因是质子与半导体材料中的原子非弹性碰撞而形成的团簇缺陷。     

邮电部固体器件研究所制作的镓铝砷激光器寿命已超过二千小时

近年来,我所制作了一些质子轰击隔离的GaAs—Al_xGa_(i-x)As双异质结条形激光器,提供我院激光通信研究所5.7公里光纤通信试验段使用。今年又制作了一批,并对一些激光器进行了寿命考验。其中几只管子已经室温连续激射2000小时,目前仍在继续工作。我们采用过冷式工艺,用通常的水平滑动舟制成四层结构的外延片。为了得到比较好的限制我们选的x值为0.42。在外延过程中不使用扩散泵以避免泵油对反应系统的污染。用较长时间的通氢来实现排氮。     

GaAlAs/GaAs DH 激光器的L-I特性

对所研制的质子轰击条形GaAlAs/GaAs DH激光器的L-Ⅰ特性及其随温度的变化进行了测量。研究了L-Ⅰ特性随考验时间的变化。个别激光器考验已超过10~4小时,仍可保持正常激射。部分激光器的L-Ⅰ特性出现了扭折,研究了这种扭折附近的近场光强分布及发射光谱。基于实事实,提出了一种有源区Al含量横向不均匀分布的物理模型,可定性地解释扭折的产生。     

5000小时室温连续激射GaAs/AlGaAs双异质结激光器

一、引言 半导体激光器采用双异质结构(DH),对有源层内的注入载流子及辐射光场进行限域,使得阈电流密度迅速下降为～1×10~3安培/厘米~2,1970年实现了室温连续激射。双异质结激光器是光纤通讯和精密测距的较理想光源,但急待解决稳定性和可靠性问题。自从对DH激光器退化机理有了比较清楚了解之后,激光器寿命基本上每年提高半个至一个数量级。到1976年美国Bell公司通过升温加速老化试验推断激光器寿命可望达到100万小时。也已采用多种方式制作各     

High single-mode power conversion efficiency vertical-cavitytop-surface-emitting lasers

We report advances in the power conversion (wall-plug) efficiency of vertical-cavity top-surface-emitting lasers. The devices were fabricated from molecular beam epitaxial layers using deep proton implants to define gain-guided lasers. The epitaxial structure included low resistance, piecewise linearly graded n-type and p-type mirrors, a triple In_0.2Ga_0.8As quantum-well active region, and a delta-doped contact layer. Power conversion efficiencies as high as 12.7% for continuous-wave single-mode operation were measured after several hours of device operation     

Degradation behavior of the active region and passive region in buried heterostructure (BH) distributed Bragg reflector (DBR) lasers

Changes in the threshold current and wavelength tuning characteristics due to the degradation of the active region and passive region in buried heterostructure (BH) distributed Bragg reflector (DBR) lasers are experimentally investigated. These changes are caused by the decrease in recombination carrier lifetime due to degradation. It is shown that the decrease in the carrier lifetime is mainly accelerated as a result of increased carrier density. This suggests that the degradation of the active region depends more strongly on the threshold current density than on the operating current. On the other hand, the degradation of the passive region is related to the injected current density, which affects the stability of the wavelength tunability of DBR lasers.     

大功率半导体激光器的腔面钝化

大功率半导体激光器的腔面退化是影响其寿命和可靠性的重要因素,长期以来一直是人们关注和研究的重点。本文利用离子铣结合腔面钝化还原层的方法对大功率半导体激光器的腔面进行处理。结果显示,离子铣腔面钝化能够在一定程度上减少半导体激光器的功率退化,168h加速老化后退化幅度降低4.5%;同时该技术对老化过程中COD阈值降低有明显的抑制作用,可有效减少使用中的突然失效。结果表明,该技术能够改善半导体激光器的腔面特性,器件的可靠性和使用寿命可望得到提高。     

Ga_(1-x)Al_xAs-GaAs DH 激光器的质子轰击研究

质子轰击条形DH激光器,通常我们采用常规的液相外延方法来制造。一般在n-GaAs衬底材料上生长Ga_(1-x)Al_xAs-GaAs五层DH结构。n面衬底上的接触电极用AuGeNi合金化形成;p-GaAs顶层上则先扩散锌,蒸发Cr-Au。对质子束的掩蔽     

Shockley–Read–Hall Lifetime Study and Implication in HgCdTe Photodiodes for IR Detection

The Shockley–Read–Hall (SRH) mechanism might be a limiting factor of an infrared (IR) photodiode's dark current. This limitation is twofold. SRH generation might occur in the depletion region of the photodiode. In that case, the corresponding current is usually limiting the low-temperature dark current. Moreover, SRH generation might also occur in the diffusion volume, close to the space charge region, resulting in an increase of the diffusion dark current, usually limiting the high-temperature behavior of the photodiode. Hence, the determination of the SRH lifetime of IR materials is of first importance and has to be measured (or at least estimated) to define upcoming trends in future high-performance IR detectors. During the last few years, a lot of papers have been published about SRH lifetime in III–V materials (InSb, superlattices, InAsSb) and a few other communications have been more focused on comparing different material systems including III–V and II–VI materials. Those latter communications proposed very long SRH lifetimes (longer than ms) for HgCdTe, instead of the classical 10–100 μs usually admitted until now. This paper aims at investigating this SRH lifetime in HgCdTe based on experimental measurements carried out at the Laboratoire d’électronique des technologies de l’information (LETI) on HgCdTe grown in-house. Direct lifetime measurement (photoconductive or photoluminescence decay) as well as indirect estimations from photodiode dark currents are discussed in order to clarify this question of SRH lifetime and its consequences in upcoming advanced IR detection structures. In the end, it appeared that except for p/n extrinsic heterojunctions (for which the narrow gap depleted volume is not well known), most of the devices tested seemed limited by SRH lifetimes in the 10–100-μs range.     

Lasing wavelength changes due to degradation in buriedheterostructure distributed Bragg reflector lasers

Changes in the wavelength and lamp characteristics due to the degradation of distributed Bragg reflector (DBR) lasers are investigated and the lasers are confirmed to be reliable enough for application as the light sources in WDM systems. The change in wavelength characteristics is due to degradation of the DBR or phase control region and the change in lamp characteristics is due to the degradation of active region. These changes in the characteristics are caused by diminished recombination carrier lifetime. The wavelength stability is strongly correlated with the injected current density. The lamp characteristics is confirmed to be almost as stable as in conventional Fabry-Perot lasers. The applicability of DBR lasers as the light source for wavelength division multiplexing (WDM) systems is demonstrated for actual-use conditions     

高频大功率InGaAsP/InP SPB-BC激光器

在普通掩埋新月型激光器的基础上,提出了一种高频大功率的InGaAsP/InP激光器结构——选择性质子轰击掩埋新月型(SPB-BC),并对激光器结构模型进行了理论分析。采用p-InP衬底,最大输出功率为80mW。500μm腔长激光器,它的调制带宽可以达到6.0GHz。     

Gain and carrier lifetime measurements in AlGaAs multiquantum well lasers

We have measured the gain and the carrier lifetime at threshold in shallow proton stripe AlGaAs multiquantum well lasers with several different active layer structures. The lasers studied had active layers with two wells, four wells, six wells, and the modified multiquantum well. The net gainGis found to vary almost linearly with the injection currentIfor all the laser structures studied. The slopedG/dIis largest for the modified multiquantum well (MMQW) laser which is consistent with the observed lowest threshold current of these devices. We find that the carrier density at threshold for the MMQW laser is about a factor of 4 lower than that for a single quantum well laser. Thus, the effect of a nonradiative mechanism (e.g., Auger effect) which varies superlinearly with the injected carrier density is considerably reduced in MMQW lasers compared to that in single quantum well (SQW) lasers or the conventional double heterostructure lasers. The reduced threshold carrier density of the MMQW lasers has important implications for high temperature performance of lasers fabricated from the InGaAsP/InP material systems which are believed to have nonradiative mechanisms that vary superlinearly with carrier density, particularly for those laser structures for which the high temperature operation is not limited by leakage current.     

Comparison of the aging behavior of diffused and epitaxial GaAlAs heterojunction electroluminescent diodes

Two Types of GaAlAs heterojunction electroluminescent diodes are compared. In the planar-type diffused diode the p-n homojunction is obtained by zinc diffusion in areas limited by a silicon nitride mask; the p-p heterojunction confines electrons in the bulk and avoids surface recombinations. The epitaxial diode is a conventional double heterojunction; the active area is limited by proton bombardment. The aging behaviors of these two types appear quite different. Diffused diodes degrade relatively fast; under continuous operation at 550 A/cm²(100 mA) the device lifetime (emitted light power falling down to 50 percent of the initial value) is 10 000 to 50 000 h. Epitaxial diodes degrade much more slowly; their device lifetime is estimated at several 10⁵h. The degradation is followed during aging, by using electrical and optical measurements, together with SEM and TEM analyses. It is confirmed that fast degradation occurs with simultaneous growth of dark line defects (DLD) and that these DLD's result from dislocation dipoles of interstitial nature, emitted either from scratches or, more frequently, from previously existing dislocations. It is shown that epitaxial diodes are practically free of dislocations; on the contrary, in the case of planar-type p-n junctions, a large number of dislocation loops are developed at the junction periphery, resulting from the mechanical stress at the edge of the junction during processing. This is the main source of DLD's and fast degradation of planar-type diffused diodes.