Properties of Ga vacancies in AlGaAs materials

Kahen, K. B.; Peterson, D. L.; Rajeswaran, G.; Lawrence, D. J.

doi:10.1063/1.101811

Cited by 60 publications

(15 citation statements)

References 16 publications

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“…No comprehensive explanation of the mechanisms involved was presented until 1988 [2], when a quasi-equilibrium Fermi level model was developed to describe the intermixing of GaAs-AlGaAs heterostructures. Although limited modeling work has followed, it is mostly either incomplete or has only described trends rather than relating the underlying physics to experimental observations [3]- [7]. Individual factors such as the Fermi level effect, the As overpressure, as well as the other experimental parameters were correlated using basic physical relationships such as the Gibbs phase rule [8].…”

Section: Introductionmentioning

confidence: 99%

Quantitative model for the kinetics of compositional intermixing in GaAs-AlGaAs quantum-confined heterostructures

Helmy

Aitchison

Marsh

1998

IEEE J. Select. Topics Quantum Electron.

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A quantitative atomic-scale model for the kinetics of intermixing in GaAs-AlGaAs quantum-confined heterostructures is presented. The model takes into account the statistical nature of the defect diffusion through heterostructures and calculates its effect on the Ga-Al interdiffusion across the associated interfaces. The model has been validated by successfully predicting the observed amounts of bandgap shift induced by the process of hydrogen plasma induced defect layer intermixing, as well as for the process of impurity-free vacancy disordering using SiO2 caps. Good agreement between calculated and measured bandgap shifts has been observed. Values of the group-III vacancy diffusion coefficient, where the agreement took place, are between 2 and 3 2 exp[02:72=kBT ] cm 2 1s 01 . Index Terms-Diffusion processes, quantum heterostructures, quantum-well interdiffusion, quantum wells.

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Section: Introductionmentioning

confidence: 99%

Quantitative model for the kinetics of compositional intermixing in GaAs-AlGaAs quantum-confined heterostructures

Helmy

Aitchison

Marsh

1998

IEEE J. Select. Topics Quantum Electron.

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“…Since the Ga vacancy has a much larger diffusion coefficient than the arsenic antisite defect, the Ga vacancy in the LT-GaAs layer is the dominant defect to cause the intermixing in the AlGaAs/GaAs superlattice. The diffusion mechanism is similar to that of the SiO 2 capped layer enhanced interdiffusion, 4,11 which is also caused by the Ga vacancy diffusion. We have simulated the diffusion process numerically.…”

Section: Resultsmentioning

confidence: 84%

Compositional disordering of AlGaAs/GaAs superlattices by using the low-temperature grown GaAs

Tsang¹

1995

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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The use of low-temperature (∼200 °C) grown GaAs by molecular beam epitaxy to induce compositional disordering of AlGaAs/GaAs superlattices has been studied. After furnace annealing between 700 and 850 °C for 30 min, an obvious blue shift in the peak wavelength of the superlattice emission is observed by the 77 K photoluminescence (PL), indicating that the emission has been changed from that of the GaAs quantum wells to that of the intermixed AlGaAs. The PL shift and the depth profile of Al concentration measured by secondary ion mass spectrometry indicate that the superlattice is nearly totally disordered after 850 °C annealing.

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“…En referencia a esto, varios autores (2,3) han postulado que el crecimiento a baja temperatura de estructuras III-V induce a la existencia de una alta concentración de As en exceso, lo cual produce vacantes del grupo III, susceptibles de difundir bajo un tratamiento térmico (4). Además, diversos estudios han mostrado que el coeficiente de difusión de las vacantes de Ga es muy elevado (2). Según esto, en la muestra CS300Ct y en las CD, crecidas a baja temperatura y con un posterior aumento de temperatura, deberá existir una alta concentración de vacantes de Ga que difundirán al subir la temperatura, lo cual podría provocar un proceso de escalada de dislocaciones.…”

Section: Discussionunclassified

Estudio de capas de desacoplo de InGaAs/GaAs(001) por crecimiento combinado de MBE-ALMBE en forma dinámica y escalonada

Herrera¹,

González²,

González³

et al. 2004

Bol. Soc. Esp. Ceram. Vidr.

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El estudio mediante Microscopía Electrónica de Transmisión (TEM) de capas InGaAs/GaAs(001) crecidas a 200ºC reflejó la existencia de una red de dislocaciones de Lomer en el seno de la capa, muy prometedora para la efectiva relajación de la estructura con una disminución en la densidad de dislocaciones de propagación. Sin embargo, la capa presentaba un grado de relajación deficiente, por lo que resultaba metaestable. Con el fin de aprovechar las ventajas que ofrecía dicha red de Lomer, se crecieron capas de desacoplo a 200ºC seguidas de una capa a 400º o 500ºC (en forma dinámica y escalonada) para relajar completamente la estructura. No obstante, no se consiguió reproducir la mencionada red, observándose otra constituida por dislocaciones de 60º, situada en la zona de cambio entre las dos temperaturas de crecimiento utilizadas. Las razones de este cambio se discuten en el trabajo. Palabras clave: relajación, dislocaciones de Lomer, capas amortiguadoras, InGaAs/GaAs(001), TEM Study of InGaAs/GaAs(001) buffers by combined growth of ALMBE-MBE in dynamic or stepped wayTransmission Electron Microscopy study of low temperature (200º C) grown InGaAs/GaAs(001) layers showed an unexpected Lomer dislocation network in the middle of the layer, which appears as a promising one for the effective structure relaxation without a high density of threading dislocations. However, the layer remained metastable, due to a lack in the relaxation degree. To take advantage of such a network, buffers layers were grown at 200º C by ALMBE, followed by a layer grown at 400ºC or 500ºC (in a dynamic and a stepped way), in order to reach the complete relaxation of the structure. Nevertheless, the Lomer network did not appear, substituted by a 60º dislocations one, placed in the region with the growth temperature change. The reasons of this change are discussed.Keywords: relaxation, Lomer dislocation, buffer, InGaAs/GaAs(001), TEM INTRODUCCIÓNLa industria optoelectrónica se encuentra sujeta a la optimización del crecimiento epitaxial de heteroestructuras semiconductoras con ancho de banda prohibida adecuado para el desarrollo de sus dispositivos. En este sentido, la introducción de capas de desacoplo (CD) entre el substrato y las capas de interés se perfila como una opción adecuada para controlar los defectos reticulares característicos en estos sistemas. El trabajo que se propone se enfoca a un nuevo diseño de capas de desacoplo, donde se aprovechen las características microestructurales observadas al crecer a baja temperatura, como la aparición de una red de dislocaciones de Lomer situadas en el seno de la epicapa. Estos defectos relajan la estructura más eficientemente que las dislocaciones de 60º, por lo que habrá una disminución en la cantidad de dislocaciones de propagación que puedan deslizar y atravesar el dispositivo, lo que supone una ventaja estructural fundamental para el crecimiento epitaxial de heteroestructuras con fines optoelectrónicos. MATERIALES Y MÉTODOEn el presente trabajo se estudian dos capas simples y tres CD de InGaAs/G...

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Properties of Ga vacancies in AlGaAs materials

Cited by 60 publications

References 16 publications

Quantitative model for the kinetics of compositional intermixing in GaAs-AlGaAs quantum-confined heterostructures

Quantitative model for the kinetics of compositional intermixing in GaAs-AlGaAs quantum-confined heterostructures

Compositional disordering of AlGaAs/GaAs superlattices by using the low-temperature grown GaAs

Estudio de capas de desacoplo de InGaAs/GaAs(001) por crecimiento combinado de MBE-ALMBE en forma dinámica y escalonada

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