Mechanical strain and defect distributions in GaAs-based diode lasers monitored during operation (original) (raw)
Related papers
Tensile strain and threshold currents in GaAsP-AlGaAs single-quantum-well lasers
IEEE Journal of Quantum Electronics, 1996
The effects of tensile strain on threshold current in GaAsP-AlGaAs quantum well lasers are studied theoretically and experimentally. A comprehensive model for the light-current characteristics of separate-confinement strained-layer lasers, which is based on a six-band Luttinger-Kohn valence dispersion model, is first developed. Theoretical and experimental results for broad stripe single-well laser diodes with a constant well width of 115 A are then presented. Experimentally observed variations in threshold currents and TE/TM polarization switching are accurately described by the model for phosphorus compositions in the quantum-well ranging from 0 to 0.30 and cavity lengths ranging from 300 to 1500 pm. Constant-gain contours generated from the theoretical model are shown to provide a simple and powerful guide to various regimes of operation. Our studies show that tensile-strain-related effects lower threshold currents in GaAsP-AlGaAs only in the high gain (short cavity) regime, and suggest more generally that the threshold advantages offered by tensile strain are conditional. . Publisher Item Identifier S 0018-9197(96)00343-0. Department at the University of Massachusetts, Amherst, where she is now a Professor. She initiated organometallic chemical vapor deposition (OMCVD), compound semiconductor materials and devices programs at UMass. Her research group has performed studies on heterostructures, quantum wells, strained-layers, 111-V selective epitaxy, high-frequency and photonic devices. She spent her sabbatical leave in 1989 at the MIT Lincoln Laboratory and worked with the Electro-Optical Devices Group. Dr. Lau is a recipient of the NSF Faculty Awards for Women (FAW) Scientists and Engineers. She serves on the Electronic Materials Committee of the Minerals, Metals and Materials society of AIME. Srihari Cadambi received the undergraduate degree in electronics and communication from the Indian Institute of Technology (a), Madras, India, in 1993, and is currently pursuing the Master's degree in semiconductors at the University of Massachusetts, Amherst.
Journal of Applied Physics, 2020
The stability of strained-layer heterostructure lasers can be assessed by their response to stimuli for the introduction of dislocations. Three-point bending at elevated temperatures has been applied to GaAs/InxGa1−xAs/GaAs heterostructures to apply such a thermomechanical stimulus. In each case, the middle-layer thickness was below the critical thickness predicted by the Matthews–Blakeslee model, so that the pre-test structures were fully strained with no observed misfit dislocations. The tensile stress of 46.4 MPa produced during the tests resulted in the formation of 60° misfit dislocations whose configurations changed according to the alignment of the bending axis. For bending in the [110] orientation, the misfit dislocations formed parallel to each other and to the bending axis. For [100] bending, they formed an orthogonal pattern with each dislocation at 45° to the bending axis. In each case, these misfit dislocations caused relaxation of the strained-layer structures, even th...
Tensile-strained GaAsP-AlGaAs laser diodes for reliable 1.2-W continuous-wave operation at 735 nm
IEEE Photonics Technology Letters, 2000
Tensile-strained GaAsP quantum wells embedded in AlGaAs large optical cavity structure were investigated at an emission wavelength of 735 nm. 1.2-W continuous-wave operation for 100-m stripe width diode lasers over 1000 h is reported. Experiments with different stripe widths showed a high stability at an output power of 12-mW/ m stripe widths with degradation rates below 5 10 5 h 1 , i.e., lifetimes larger than 5000 h could be expected.
Packaging-induced stress distribution in high power AlGaAs laser diodes by photoluminescence mapping
Materials Science and Engineering: B, 2001
The microphotoluminescence (m-PL) technique is proposed for mapping local stress distribution in GaAs/AlGaAs high power laser diode arrays (LDAs). This technique will be used to monitor the stresses that can be induced on the bars during the packaging process. We show herein that also a detailed study of the stress profiles that could exist in the bars before mounting and after aging can be achieved with this technique.
Microscopic Determination of Stress Distribution in GaAs Grown at Low Temperature on GaAs (100)
MRS Proceedings
ABSTRACTA microscopic strain distribution across commensurate interfaces between GaAs layers grown on semi-insulating GaAs substrates was observed by means of convergent beam electron diffraction (CBED) and large angle convergent beam methods (LACBED). Strain relaxation at a specific distance from the interface was observed in these layers without formation of misfit dislocations. It was proposed that specific point defects distributed close to the interface can explain the asymmetric broadening of high-order Laue zone (HOLZ) lines in the CBED patterns.
Bonding stress and reliability of high power GaAs-based lasers
Components and Packaging …, 2001
effect of applied force on unmounted GaAs-based laser chips is studied on the resulting stress in the lasers and the degradation rate of the operating laser. Major conclusions from the experiments in this thesis are discussed in Chapter 5. Suggestions for further research are outlined in Chapter 6, and references cited in this thesis are listed in the final chapter.
IEEE Photonics Technology Letters, 2000
The strain caused by device packaging was studied in high-power semiconductor laser bars by measuring the degree of polarization. Polarization measurement with intentionally GaAsP-GaInP strained laser bar packaged on a Cu heat sink for 799-nm emission revealed the variation of band edges between the conduction band and heavy-hole or light-hole bands in the active region. This served as a method for evaluating the strain. In the packaging process, a maximum of 1800-ppm strain was transmitted to the active region. It was found that the defect density of 14.3% was induced.
Analysis of bulk and facet failures in AlGaAs-based high-power diode lasers
Novel in-Plane Semiconductor Lasers Xii, 2013
Mechanisms are addressed limiting the reliability high-power diode lasers. An overview is given on the kinetics of the Catastrophic Optical Damage (COD) process, which is related to highest output powers. It involves fast defect growth fed by re-absorption of laser light. Local temperatures reach the order of the melting temperature of the waveguide of the device. The process starts either at a facet or at any weak point, e.g., at extended defects in the interior of the cavity.
Applied Physics Letters, 2002
Strain evolution during In 0.2 Ga 0.8 As/GaAs ͑001͒ growth by molecular beam epitaxy has been monitored in real time. We have detected that three main relaxation stages, related to different mechanisms, take place during growth, and we have obtained the thickness range where those mechanisms are active. The in situ measured relaxation behavior in the plastic stages has been described by means of a simple equilibrium model that takes into account dislocations generation and interaction between them. The excellent agreement between the experimental data and the model allows us to determine the value of the formation energy per unit length of a misfit dislocation and the extent of the interaction between dislocations in this material system.
Journal of Physics D: Applied Physics
In this work we investigate the catastrophic optical damage (COD) of graded-index separate confinement heterostructure (GRINSCH) quantum well (QW) laser diodes based on AlGaAs/GaAs. The emphasis is placed on the impact that the physical properties at the nanoscale level have on the operation and degradation of the active layers of these devices. When these laser diodes run in continuous wave (cw) mode with high internal optical power densities, the QW and guide layers can experiment very intense local heating phenomena that lead to device failure. A thermo-mechanical model has been set up to study the mechanism of degradation. It has been solved applying finite element methods (FEM) considering a variety of physical factors, related to the materials properties, which play a paramount role in the laser degradation process. The reduced thicknesses of the QW and the guides lead to thermal conductivities smaller than the bulk figures, which are further reduced as extended defects develop in these layers. This is, to the best of our knowledge, the first model for electronic devices to have taken into account low scale effects that result in enhanced mechanical strengths in the layers. The consequences of these size-dependent properties on the thermo-mechanical behaviour on the route to COD are examined. Finally, the possibility of taking advantage of these properties in order to design robust devices in a controlled manner is addressed.