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GaAs Buffer Layer Morphology and Lateral Distributions of InGaAs Quantum Dots



Alexana Roshko, Todd E. Harvey, Susan Y. Lehman, Richard Mirin, Kristine A. Bertness, Brittany Hyland


Atomic force microscopy was used to study the morphology of GaAs buffer layers and the density and height distributions of self-assembled InGaAs quantum dots (QDs) grown on these buffers by molecular beam epitaxy. The surface roughness and terrace size of 500 nm thick buffers were found to be independent of substrate preparation technique, but did vary depending on whether the buffers were grown either continuously, with a pulsed start, or with a final anneal. A short anneal at the QD growth temperature increased both the size of surface features and the height of mounds on the buffer grown with a pulsed start. The variations in dot distributions on these three buffer types were similar, indicating that the density of step edges does not determine the density of QDs. The standard deviation in dot density was found to vary from 16 to 28 % of the average dot density across the central 26 x 26 mm2 region of 5 cm wafers. The standard deviation in dot height was 10 % or less of the average height. An inverse relationship was found between the dot height and density distributions, suggesting that a uniform amount of QD material was deposited on the wafers, but that the nucleation of dots was nonuniform.
Journal of Vacuum Science and Technology


buffer layers, density, GaAs, InGaAs, morphology, nucleation, QD, quantum dots


Roshko, A. , Harvey, T. , Lehman, S. , Mirin, R. , Bertness, K. and Hyland, B. (2005), GaAs Buffer Layer Morphology and Lateral Distributions of InGaAs Quantum Dots, Journal of Vacuum Science and Technology, [online], (Accessed April 13, 2024)
Created April 30, 2005, Updated October 12, 2021