GaAs/GaAlAs双异质结激光器退化的研究(摘要)

我们观察了室温下工作的DH激光器的退化现象,发现在短时间内退化的器件除阈值升高外尚伴随着微分量子效率的下降。这些器件中观察到了暗线缺陷的形成。还有一些较快退化的器件则只有阈值的上升,而量子效率基本上不变。观察到这些器件中往往出现腔面的损伤。对热稳定性良好并于较长时间(>250小时)阈值上升率(△J_(th)/J_(th)千小时)小于3%的器件,高温老化证明它们的寿命都能超过万小时量级。     

可见光阶梯衬底内条形半导体激光器

将所设计的新结构半导体激光器──阶梯衬底内条形激光器推进到可见光波段(0.75—0.80μm)。器件直流阈值最低26mA,光功率线性15—20mW,2—4 I_(th)基模工作,4mW工作寿命已超过5000小时。本文还讨论分析了该结构器件可靠性改善的原因。     

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     

电磁脉冲应力下MOS器件退化失效建模

通过分析电磁脉冲应力下,栅氧化层软击穿(MOS器件主要失效模式)的失效机理,得出结论:它符合基于随机过程的退化失效模型。根据此结论,提出利用该模型来描述电磁脉冲应力下MOS器件的退化失效过程,并给出相应的退化失效模型。同时针对退化失效模型中的失效阈值问题,研究了随机失效阈值问题,分析了周期电磁脉冲应力下MOS器件的失效阈值问题,给出动态应力-强度干涉(SS)I模型。这些为更合理描述和分析MOS器件的退化失效问题提供了新的途径。     

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.     

改进了的InGaAsP注入激光器双异质结材料光学测试技术

光致发光(PL)法一般用于对InGaAsP激光材料的测定,以确定材料的组份并揭示其非辐射缺陷。在这项工作中,我们证实它还可以大大推广,用来确定注入激光器晶片的重要参数,如Pn结位错、P型体电阻以及预测内部量子效率和宽面积激光器(BAL)的阈值电流密度(J_(th)。我们证实了用光致发光法测试双异质结(DH)激光晶片的临界条件,那就是:在任何有源层带有Pn结的异质结中—即使无缺陷,如果光泵浦源不大于阈值级P_(th)(见     

低阈值1.5μm平面掩埋脊型(PBR)分布反馈激光器

采用质子轰击的PBR 结构,研制了室温阈电流小于15mA,高稳定单纵模输出的1.5μmDFB激光器.为今后研制长寿命无致冷1.5μmDFB激光器组合件奠定了基础,在大温度范围(-40-+60℃)和大工作电流范围(1.2-3I_(th)内可稳定单纵模工作,边模抑制比(SMSR)可达30dB以上.静态线宽一般为30-40MHz,最窄可低于20MHz.器件经50℃恒功加速老化实验,外推20℃连续工作时间已超过3000小时无显著退化迹象.本器件已首次在国内做为信号源成功地用在140Mb/S相干光通信系统上.     

反应离子刻蚀铝中nMOS 器件的等离子充电损伤

介绍在等离子工艺中的等离子充电损伤,并且利用相应的反应离子刻蚀(RIE)Al的工艺试验来研究在nMOSFET器件中的性能退化。通过分析天线比(AR)从100:1到10000:1的nMOSFET器件的栅隧穿漏电流,阈值Vt漂移,亚阈值特性来研究由Al刻蚀工艺导致的损伤。试验结果表明在阈值Vt漂移中没有发现与天线尺寸相关的损伤,而在栅隧穿漏电流和低源漏电场下亚阈值特性中发现了不同天线比的nMOS器件有相应的等离子充电损伤。在现有的理解上对在RIEAl中nMOS器件等离子充电损伤进行了讨论,并且基于这次试验结果对减小等离子损伤提出了一些建议。     

大功率量子阱远结半导体激光器

通过将下波导层掺杂为ｐ型,使半导体激光器的有源区与ｐｎ结分离,制作了大功率远结半导体激光器。该器件在老化期间表现出输出功率变大的趋势。理论分析表明,远结半导体激光器特殊的外延结构,决定了器件的阈值比正常器件的高,但是阈值受温度的影响较小,并且器件的退化机制转变为ｐｎ结的退化,这对于制作高可靠性、长寿命、低温度敏感性的半导体激光器具有重要意义。     

(GaAl)As/GaAs质子轰击隔离条形DH激光器的退化原因

对研制的(GaAl)As/GaAs质子轰击隔离条形DH激光器的退化原因进行了实验分析。结果表明:快退化主要起因于有源区内的暗点、暗线及暗区等缺陷的增殖;腔面氧化是限制寿命在千小时的原因之一;质子轰击引入的点缺陷移入有源区是器件限制寿命在万小时的原因之一。     

Threshold dependence on active-layer thickness in InGaAsP/InP d.h. lasers

Room-temperature threshold current density Jth against active-layer thickness d is reported for pulsed InGaAsP/InP double-heterostructure lasers operating at wavelengths near 1.23 ?m. For d ? 1 ?m, Jth/d is 5.0 kA cm?2 ?m?1, whereas the lowest threshold is 1.6 kA cm?2 for d ? 0.2 ?m. The threshold dependence is fitted by a numerical calculation based on a two-parameter gain model.     

InGaAs／InGaAsP分别限制应变量子阱激光器的研制及其特性研究

报道了利用ＬＰ－ＭＯＶＰＥ技术生长高质量的ＩｎＧａＡｓ／ＩｎＧａＡｓＰ分别限制应变量子阱激光器结构材料、激光器制作和结果．宽而激光器实现了室温脉冲受激发射．激射波长为１．４９μｍ，在腔长为２０００μｍ时，最低阈值电流密度为０．３０ｋＡｃｍ－２．最大脉冲光输出峰值功率达５００ｍＷ以上．同时，从理论和实验上研究了阙值电流及阙值电流密度随激光器腔长的变化关系，并与ＬＰ－ＭＯＶＰＥ生长制作的宽面双异质结构激光器进行了比较．     

Influence of growth conditions on the threshold current density of double-heterostructure lasers prepared by molecular-beam epitaxy

The effect on threshold current density Jth of the use of an air-lock sample-exchange mechanism, substrate preparation and Al source purity was investigated for GaAs-Al0.27 Ga0.73 As double-heterostructure lasers grown by molecular-beam epitaxy (m.b.e.). The conditions necessary to prepare m.b.e. wafers that give Jth as low as for wafers prepared by liquid-phase epitaxy (Jth ? 1 × 103 A/cm2 for an active layer thickness of 0.1 ?m) are summarised.     

Strain-compensated InGa(As)P-InAsP active regions for 1.3-μmwavelength lasers

The demonstration of an optimized strain compensated multiple-quantum-well (MQW) active region for use in 1.3-μm wavelength lasers is described. Utilizing narrow bandgap tensile-strained InGaAsP instead of wide bandgap InGaP barriers in strain-compensated lasers, we observe a reduction in threshold current density (Jth) from 675 to 310 A/cm² and in T₀ from 75 K to 65 K for 2-mm long seven quantum-well devices. Additionally, the lowest reported Jth for MBE grown 1.3-μm wavelength lasers of 120 A/cm² for single-quantum-well (SQW) 45-mm-long lasers was attained     

Grating-coupled GaAs-GaAlAs lasers with distributed Bragg reflectors

Grating-coupled GaAs-GaAIAs lasers with 4th-order distributed Bragg reflectors have been successfully demonstrated with high efficiencies. The threshold current density, lasing spectrum and grating-coupled output power have been measured at room temperature. The output power from the grating at 1.5 Jth and its differential quantum efficiency have been measured to be 13.5 mW and 1.1%, respectively.     

High Power InGaAsP/GaAs SCH SQW Lasers

InGaAsP/GaAs SCH SQW laers have been prepared by LPMOCVD.The dependence of threshold current density on cavity length was explained.Laser diodes are characterized by the output power of 1 W 20 W,threshold current density(Jth)of 330A/cm^2 to 450A/cm^2 and external differential quantum efficiency(ηd)of 35% to 75% ,and these characteristics are in good agreement with the designed requirement.     

Reduction of threshold current density of 2.2?m GaInAsSb/AlGaAsSb injection lasers

GaInAsSb/AlGaAsSb injection lasers have been fabricated with increased Al concentration in the cladding layers. As a result of improved optical and electrical confinement, the threshold current density Jth for these double heterostructures was a factor of two lower than reported previously; CW operation was achieved up to 235 K.     

Room temperature CW operation of GaInAsP/InP double heterostructure diode lasers emitting at 1.5 ?m grown by low pressure metalorganic chemical vapour deposition (LP-MO CVD)

Room temperature continuous wave (CW) operation at 1.5 ?m has been achieved in GaInAsP/InP DH lasers fabricated on material grown by low-pressure metalorganic chemical vapour deposition (LP-MO CVD). Threshold currents as low as 200 mA DC have been measured for devices with a stripe width of 9 ?m and a cavity length of 300 ?m. Values of To as high as 64 K have been obtained, where To is defined by the expression Jth(T) = Jth(0) exp (T/To). Fundamental transverse mode oscillation has been achieved up to an output power of 10 mW.     

Single-Facet Folded-Cavity Diode Laser With Ultrasmall Bend Radius High-Index-Contrast Oxidized AlGaAs Ridge Waveguide

AlGaAs heterostructure high-index-contrast (HIC) ridge waveguide (RWG) diode lasers incorporating a folded-cavity single-facet resonator with a folding bend radius as small as r=10 mum are demonstrated. Fabricated by a self-aligned deep dry etch (through the active region) plus nonselective O₂-enhanced wet thermal oxidization process, the low-index, insulating, and interface-passivating wet thermal oxide grown directly on the etch-exposed AlGaAs waveguide sidewalls yields a high lateral refractive index contrast of Deltan~1.7 and provides strong optical mode confinement. The HIC RWG device geometry also completely eliminates lateral current spreading, which results in an excellent overlap between the optical field and the gain region of the single InAlGaAs quantum-well graded-index separate confinement heterostructure. A threshold current of I_th=65mA is obtained for the r=10 mum device (a half-racetrack ring resonator), giving a threshold current density of Jth=1503 A/cm², 3.34 times higher than that of same-length straight lasers. At a bend radius of r=150 mum, I_th=16.6 mA, and J_th is comparable to straight cavity values, indicating that at this curvature there is negligible bending and scattering loss for the lowest-order waveguide mode     

Thermally accelerated degradation of 1.3 ?m BH lasers

An investigation has been made into the thermally accelerated degradation in ACC lifetests for 1.3 ?m BH lasers. The CW threshold current under high-stress aging has been evaluated at various temperatures. An increase in the CW threshold current was observed which could be represented as a combination of two linear variations. It was found that the rapid increase of the CW threshold current was dependent on the evaluation temperature, which could be an important parameter in assessing the degradation of InGaAsP lasers.