Variation of the critical layer thickness with In content in strained InGaAs/GaAs QWs grown by MBE

Department of Physics, Chalmers University of Technology, S‐412 96 Göteborg, Sweden
Applied Physics Letters (Impact Factor: 3.3). 10/1987; 51(10):752 - 754. DOI: 10.1063/1.98856
Source: IEEE Xplore


The critical width L c for misfit dislocation generation has been determined for molecular beam epitaxy grown strained In x Ga 1 -x As (0.1≪x≤1) quantum wells in a GaAs matrix by means of photoluminescence measurements. For the full alloy region the dependence L c (x) is in good agreement with the theoretical expression proposed by J. W. Matthews and A. E. Blakeslee [J. Cryst. Growth 27, 118 (1974)].

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    ABSTRACT: Se presenta un estudio mediante Microscopía Electrónica de Transmisión (TEM) y Fotoluminiscencia (PL) de espesores críticos de epicapa (CLT) en pozos cuánticos simples de InGaAs/GaAs crecidos sobre substratos de GaAs con orientaciones (001) y (111)B. Los resultados obtenidos demuestran que la disminución de la señal luminiscente del espectro de PL se debe a distintos mecanismos de relajación para cada orientación de sustrato. Así, en sustratos orientados (001), el CLT viene definido por la transición desde un frente de crecimiento plano (2D) a otro ondulado (3D). Sin embargo, la relajación plástica debida a una red de dislocaciones de desajuste (DD) determina el CLT en sustratos orientados (111)B. El análisis por TEM de esta red de dislocaciones muestra la existencia de una nueva configuración de DD distinta a la anteriormente descrita en la bibliografía. La nueva configuración observada permite explicar los resultados experimentales obtenidos para el caso de SQW de InGaAs/ GaAs (111)B utilizando los modelos clásicos de CLT de formación de la primera DD.
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    ABSTRACT: The aim of this work is to examine the effect of dilute nitride and/or antimonite on the critical layer thickness of GaInAs quantum wells on GaAs and InP substrates by means of Matthews and Blakeslee force model. The study provides a comparison of the critical layer thickness of the related GaIn(N)As(Sb) QWs in (001) and (111) orientation. Our calculations indicate the importance of antimonite and the proper usage of it with dilute nitrides in order to tailor the active layer thickness and emission wavelength of quantum well laser devices. PACS73.21.Fg Quantum wells-73.61.Ey III-V semiconductors-42.55.Px Semiconductor lasers; laser diodes-42.60.Mi Dynamical laser instabilities; noisy laser behavior
    Physics of Condensed Matter 05/2009; 69(2):211-218. DOI:10.1140/epjb/e2009-00151-2 · 1.35 Impact Factor
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    ABSTRACT: For a long time, there has been a desire to extend the emission wavelength of GaAs-based quantum well lasers, with the aim of eventually replacing InP with GaAs as the substrate of choice for communication applications. Using dilute nitride GaInAsN QWs or InAs quantum dots, emission wavelengths have successfully been extended to 1.3 m, but significant difficulties have been met going beyond 1.3 m. In this thesis, we present an alternative approach, namely, the molecular beam epitaxy (MBE) growth of quantum wells on top of indium gallium arsenic compositionally graded buffers, with the indium composition in the buffers linearly graded from 0% to 15% or 20%. We observed that one can obtain strong quantum emission on top of such graded buffers only under a very restricted range of growth conditions, detailed in this thesis, which are not compatible with the subsequent growth of the aluminum-containing barriers necessary for carrier confinement. Furthermore, upon proper ex-situ annealing, it was able to obtain QW emission as strong as, sometimes even stronger than, that from QWs pseudomorphically grown on GaAs. However, when even slight tensile or compressive strain was added to the QWs, severe degradation occurred, which was likely related with the amount of surface roughness induced by the crosshatches developed during and after the growth of the graded buffers. Temperature dependent photoluminescence was employed as a tool to investigate the relationship between the ex-situ annealing, strain and quantum well photoluminescence. It was found that there was a significant PL decay mechanism between 50K to about 250K for the aluminum containing unannealed quantum well samples. For the unstrained ones, this mechanism could be removed effectively by annealing. However, strain in quantum well was observed to retard this removal. The same observations were made in both the pseudomorphically and metamorphically grown samples, but the metamorphic ones seemed to suffer more from the retardation. Finally, the theoretical modeling of the photoluminescence temperature dependence was reformulated such that physical processes or band diagram features could be related to the measurement results. Only under restricted circumstances, our formulation was found to be identical to the existing, commonly used, description of the photoluminescence temperature dependence. Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005. Includes bibliographical references (p. 161-174).
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